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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

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AC: Alternating Current 

ACBM: Acronym for "asbestos-containing building material." 

Account classification: The way in which suppliers of electricity, natural gas, or fuel oil classify and bill their customers. 

Commonly used account classifications are "Residential," "Commercial," "Industrial," and "Other." Suppliers' definitions of 

these terms vary from supplier to supplier. In addition, the same customer maybe classified differently by each of its energy 

suppliers. 

Account of others (natural gas): Natural gas deliveries for the account of others are deliveries to customers by 

transporters that do not own the natural gas but deliver it for others for a fee. Included are quantities covered by long-term 

contracts and quantities involved in short-term or spot market sales. 

Accounting system: A method of recording accounting data for a utility or companyor a method of supplying accounting 

information for controlling, evaluating, planning and decision-making. 

Acid mine drainage: This refers to water pollution that result If-bearing minerals associated with coal are 

exposed to air and water and form sulf !fate. The ferrous sulfate can further react to form ferric 

hydroxide, or yellow boy, a yellow-orange iron precipitate found in streams and rivers polluted by acid mine drainage. 

Acid rain: Also called acid precipitation or acid deposition, acid rain is precipitation containing harmful amounts of nitric 

and sulfuric acids formed primarily by sulf trogen wddes released into the atmosphere when fossil f Is are 

burned. It can be wet precipitation (rain, snow, or fog) or dry precipitation (absorbed gaseous and particulate matter, aerosol 

particles or dust). Acid rain has a pH below 5.6. Normal rain has a pH of about 5.6, which is slightly acidic. The term pH is a 

measure of acidity or alkalinityand ranges from 0 to 14. ApH measurement of 7 is regarded as neutral. Measurements 

below 7 indicate increased acidity, while those above indicate increased alkalinity. 

Acquisition (f I): All transfers of ownership of foreign crude oil to a firm, irrespective of the terms of that 

transfer. Acquisitions thus include all purchases and exchange receipts as well as any and all foreign crude acquired under 

reciprocal buy-sell agreements or acquired as a result of a buy-back or other preferential agreement with a host 

government. 

Acquisition (minerals): The procurement of the legal right to explore for and produce discovered minerals, if any, within a 

specific area; that legal right maybe obtained by mineral lease, concession, or purchase of land and mineral rights or of 

mineral rights alone. 

Acquisition costs, mineral rights: Direct and indirect costs incurred to acquire legal rights to extract natural resources. 

Direct costs include costs incurred to obtain options to lease or purchase mineral rights and costs incurred for the actual 

leasing (e.g., lease bonuses) or purchasing of the rights. Indirect costs include such costs as brokers' commissions and 

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expenses; abstract and recording fees; filing and patenting fees; and costs for legal examination of title and documents. 

Acre-foot: The volume of water that will cover an area of 1 acre to a depth of 1 foot. 

Acreage: An area, measured in acres, that is subject to ownership or control bythose holding total or fractional shares of 

working interests. Acreage is considered developed when development has been completed. A distinction maybe made 

between "gross" acreage and "net" acreage: 

• Gross - All acreage covered by anyworking interest, regardless of the percentage of ownership in the interest 

• Net- Gross acreage adjusted to reflect the percentage of ownership in the working interest in the acreage. 

Active power: The corn ponent of electric power that performs work, typically measured in kilowatts (kW) or 

megawatt (M ). Also known as "real power." The terms "active" or "real" are used to modify the base term "power" to 

differentiate it from Reactive Power. SeePower, Reactive Power, Apparent Power 

Active solar: As an energysource, energyfrom the sun collected and stored using mechanical pumps or fans to circulate 

heat-laden fluids or air between solar collectors and a building. 

Actual peak reduction: The actual reduction in annual peak load (measured in kilowatts) achieved by customers that 

participate in a utilitydemand-side management (DSM) program. It reflects the changes in the demand for electricity 

resulting from a utility DSM program that is in effect at the same time the utility experiences its annual peak load, as 

opposed to the installed peak load reduction capability (i.e., potential peak reduction). It should account for the regular 

cycling of energy efficient units during the period of annual peak load. 

Adequacy (electric): The ability of the electric system to supply the aggregate electrical demand and energy requirements 

of the end-use customers at all times, taking into account scheduled and reasonably expected unscheduled outages of 

system elements. NERC definition 

Adjustable speed drives: Drives that save energy by ensuring the motor's speed is properly matched to the load placed on 

the motor. Terms used to describe this category include polyphase motors, motor oversizing, and motor rewinding. 

Adjusted electricity: A measurement of electricity that includes the approximate amount of energy used to generate 

electricity. To approximate the adjusted amount of electricity, the site-value of the electricity is multiplied by a factor of 3. This 

conversion factor of 3 is a rough approximation of the Btu value of raw fuels used to generate electricity in a steamgeneration power plant. 

Adjustment bid: A bid auction conducted by the independent system operator or power exchange to redirect supply or 

demand of electricity when congestion is anticipated. 

Administrative and general expenses: Expenses of an electric utility relating to the overall directions of its corporate offices 

and administrative affairs, as contrasted with expenses incurred for specialized functions. Examples include office salaries, 

office supplies, advertising, and other general expenses. 

Advance royalty: A royalt I property that mayor may not be 

recoverable from future production. 

Advances from municipality: The amount of loans and advances made by the municipality or its other departments to the 

utility department when such loans and advances are subject to repayment but not subject to current settlement. 

Advances to municipality: The amount of loans and advances made bythe utilitydepartment to the municipality or its other 

departments when such loans or advances are subject to current settlement. 

Adverse water conditions: Reduced stream flow, lack of rain in the drainage basin, or low water supply behind a pondage 

or reservoir dam resulting in a reduced gross head that limits the production of hydroelectric power or forces restrictions to 

be placed on multipurpose reservoirs or other water uses. 

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Adverse Weather Conditions: Reduced streamflow, lack of rain in the drainage basin, or low water supply behind a 

pondage or reservoir dam resulting in a reduced gross head that limits the production of hydroelectric power or forces 

restrictions to be placed on multipurpose reservoirs or other water uses. 

Affiliate: An entity which is directly or indirectly owned, operated, or controlled by another entity. See Firm. 

Afforestation: Planting of new forests on lands that have not been recentlyforested. 

Aftermarket converted vehicle: A standard conventionally fueled, factory-produced vehicle to which equipment has been 

added that enables the vehicle to operate on alternative fuel. 

Aftermarket vehicle converter: An organization or individual that modifies OEM vehicles after first use or sale to operate on 

a different fuel (or fuels). 

AFUDC: Allowance for Funds Used During Construction 

AFV: Alternative-Fuel Vehicle 

AGA: American Gas Association 

Agglomerating character: Agglomeration describes the caking properties of coal. Agglomerating character is determined 

by examination and testing of the residue when a small powdered sample is heated to 950 degrees Centigrade under 

specific conditions. If the sample is "agglomerating," the residue will be coherent, show swelling or cell structure, and be 

capable of supporting a 500-gram weight without pulverizing. 

Aggregate ratio: The ratio of two population aggregates (totals). For example, the aggregate expenditures per household 

is the ratio of the total expenditures in each categoryto the total number of households in the category. 

Aggregator: Any marketer, broker, public agency, city ty, or special district that combines the loads of multiple end-use 

customers in negotiating the purchase of electricity the transmission of electricity, and other related services for these 

customers. 

Agriculture: An energy-consuming subsector of the industrial sector that consists of all facilities and equipment engaged 

in growing crops and raising animals. 

Agriculture, mining, and construction (consumer category): Companies engaged in agriculture, mining (other than coal 

mining), or construction industries. 

Air cleaner: A device using filters or electrostatic precipitators to remove indoor-air pollutants such as tobacco smoke, 

dust, and pollen. Most portable units are 40 watts when operated on low speed and 100 watts on high speed. 

Air collector: A m edium-tem perature collector used predominantly in space heating, utilizing pumped air as the heattransfer medium. 

Air conditioning: Cooling and dehumidifying the air in an enclosed space by use of a refrigeration unit powered by 

electricity or natural gas. Note: Fans, blowers, and evaporative cooling systems ("swamp coolers") that are not connected to 

a refrigeration unit are excluded. 

Air conditioning intensity: The ratio of air-conditioning consumption or expenditures to square footage of cooled floor 

space and cooling degree-days (base 65 degrees F). This intensity provides a way of comparing different ty 

Ids by controlling for differences in housing unit size and weather conditions. The square footage of 

cooled floor space is equal to the product of the total square footage times the ratio of the number of rooms that could be 

cooled to the total number of rooms. If the entire housing unit is cooled, the cooled floor space is the same as the total floor 

space. The ratio is calculated on a weighted, aggregate basis according to this formula: Air-Conditioning Intensity= Btu for 

Air Conditioning/(Cooled SquareFeet* Cooling Degree-Days) 

Air pollution abatement equipment: Equipment used to reduce or eliminate airborne pollutants, including particulate 

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matter (dust, smoke, fly, ash, dirt, etc.), sulfur oxides,nitrogen oxides (NOx), carbon monoxide, hydrocarbons, odors, and 

other pollutants. Examples of air pollution abatement structures and equipment include flue-gas particulate collectors, fluegas desulfurization units and nitrogen oxide control devices. 

Alcohol: The family name of a group of organic chemical compounds composed of carbon, hydrogen, and oxygen. The 

series of molecules vary in chain length and are composed of a hydrocarbon plus a hydroxyl group; CH(3)-(CH(2))n-OH 

(e.g., methanol, ethanol, and tertiary butyl alcohol). 

Alkylate: The product of an alkylation reaction. It usually refers to the high-octane product f Ikylation units. This alkylate 

is used in blending high octane gasoline. 

Alkylation: A refining process for chemically combining isobutane with olefin hydrocarbons (e.g., propylene, butylene) 

through the control of temperature and pressure in the presence of anacid catalyst, usually sulfuric acid or hydrofluoric acid. 

The product alkylate, an isoparaffin, has high octane value and is blended with motor and aviation gasoline to improve the 

antiknock value of the fuel. 

All-electric home: A residence in which electricity is used for the main source of energy for space heating, water heating, 

and cooking. Other fuels maybe used for supplementary heating or other purposes. 

Alternate energy source for primary heater: The fuel that would be used in place of the usual main heating fuel if the 

building had to switch fuels. (See Fuel-Switching Capability.) 

Alternating current (A ): An electric current that reverses its direction at regularly recurring intervals 

Alternative fuel: Alternative fuels, for transportation applications, include the following: 

• methanol 

• denatured ethanol, and other alcohols 

• fI mixtures containing 85 percent or more byvolume of methanol, denatured ethanol, and other alcohols with 

gasoline or other fuels 

• natural gas 

• liquefied petroleum gas (propane) 

• hydrogen 

• coal-derived liquid fuels 

• fIs (other than alcohol) derived from biological materials (biofuels such as soy diesel f I) 

• electricity (including electricity from solar energy) 

"... any other fuel the Secretary determines, by rule, is substantially not pet leum and would yield substantial 

energy security benefits and substantial environmental benefits." The term "alternative fuel" does not include alcohol 

or other blended portions of primarily petroleum-based fuels used as oxygenates or extenders, i.e. MTBE, ETBE, 

other ethers, and the 10-percent ethanol portion of gasohol. 

Alternative fuel vehicle converter: An organization (including companies, government agencies and utilities), or individual 

that performs conversions involving alternative fuel vehicles. An AFV converter can convert (1) conventionally fueled vehicles 

to AFVs, (2) AIly fueled vehicles, or (3) AIternative fuel. 

Alternative-fuel vehicle (AFV): A vehicle designed to operate on an alternative fuel (e.g., compressed natural gas, methane 

blend, electricity). The vehicle could be either a dedicated vehicle designed to operate exclusively on alternative fuel or a 

nondedicated vehicle designed to operate on alternative fuel and/or a traditional f I. 

Alternative-rate DSM program assistance: A DSM (demand-side management) program assistance that offers special 

rate structures or discounts on the consumer's monthly electric bill in exchange for participation in DSM programs aimed at 

cutting peak demands or changing load shape. These rates are intended to reduce consumer bills and shift hours of 

operation of equipment from on-peak to off-peak periods through the application of time-differentiated rates. For example, 

utilities often pay consumers several dollars a month (refund on their monthly electric bill) for participation in a load control 

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program. Large commercial and industrial customers sometimes obtain interruptible rates, which provide a discount in 

return for the consumer's agreement to cut electric loads upon request f the utility (usually during critical periods, such 

as summer afternoons when the system demand approaches the utiliWs generating capability). 

A Indian Coal Lease: A lease granted to a mining company to produce coal f land held in trust by the United 

States for Native Americans, Native American tribes, and Alaska Natives in exchange for royalties and other revenues. 

AMI: Advanced Metering Infrastructure is a term denoting electricity meters that measure and record usage data at a 

minimum, in hourly intervals, and provide usage data to both consumers and energy com panies at least once daily. 

A !icon: An alloy of silica and hydrogen, with a disordered, noncrystalline internal atomic arrangement, that can 

be deposited in thin-film layers (a few micrometers in thickness) by a number of deposition methods to produce thin-flm 

photovoltaic cells on glass, metal, or plastic substrates. 

A , depletion, or charge-off to expense of intangible and tangible assets over a period of time. 

In the extractive industries, the term is most frequently applied to mean either (1) the periodic charge-off to expense of the 

costs associated with non-producing mineral properties incurred prior to the time when they are developed and entered into 

production or (2) the systematic charge-off to expense of those costs of productive mineral properties (including tangible 

and intangible costs of prospecting, acquisition, exploration, and development) that had been initially capitalized (or 

deferred) prior to the time the properties entered into production, and thereafter are charged off as minerals are produced. 

A lectrical current produced in a circuit by 1 volt acting through a resistance of 1 Ohm. 

AMR: Automated Meter Reading is a term denoting electricity meters that collect data for billing purposes only and transmit 

this data one way, usually from the customer to the distribution utility. 

Anaerobic decomposition: Decomposition in the absence of oxygen, as in an anaerobic lagoon or digester, which 

produces CO2 and CH4. 

Anaerobic lagoon: A liquid-based organic waste management installation characterized bywaste residing in water at a 

depth of at least 6 feet for periods of 30 to 200 days. 

Ancillary services: Services that ensure reliability and support the transmission of electricityfrom generation sites to 

customer loads. Such services may include load regulation, spinning reserve, non-spinning reserve, replacement reserve, 

and voltage support. 

Annual operating factor: The annual fuel consumption divided by the product of design firing rate and hours of operation 

per year. 

Annual requirement: The reporting companys best estimate of the annual requirement for natural gas to make direct 

sales or sales for resale under certificate authorizations and for corn pany useand unaccounted-for gas during the year next 

following the current report year. 

ANSI: American National Standards Institute 

ANSI assembly identifier: The serial numbering scheme adopted by the American National Standards Institute (ANSI) to 

ensure uniqueness of an assemblyserial number. 

Anthracite: The highest rank of coal; used primarilyfor residential and commercial space heating. It is a hard, brittle, and 

black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of 

volatile matter. The moisture content of fresh-mined anthracite generally is less than 15 percent. The heat content of 

anthracite ranges from 22 to 28 million Btu per ton on a moist, mineral-matter-free basis. The heat content of anthracite coal 

consumed in the United States averages 25 million Btu per ton, on the as-received basis (i.e., containing both inherent 

moisture and mineral matter). Note: Since the 1980's, anthracite refuse or mine waste has been used for steam electric 

power generation. This fuel typically has a heat content of 15 million Btu per ton or less. 

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Anthropogenic: Made or generated by a human or caused by human activity. The term is used in the context of global 

climate change to refer to gaseous emissions that are the result of human activities, as well as other potentially clim atealtering activities, such as deforestation. 

API: The American Petroleum Institute, a trade association. 

API gravity: American Petroleum Institute measure of specific gravity of crude oil or condensate in degrees. An arbitrary 

scale expressing the gravity or density of liquid petroleum products. The measuring scale is calibrated in terms of degrees 

API; it is calculated as follows: 

Degrees API = (141.5 / sp.gr.60 deg.F/60 deg.F) - 131.5 

Apparent consumption, (coal): Coal production plus imports of coal, coke, and briquets minus exports of coal, coke, and 

briquets plus or minus stock changes. Note: The sum of "Production" and "Imports" less "Exports" may not equal 

"Consumption" due to changes in stocks, losses, unaccounted-for coal, and special arrangements such as the United 

States shipments of anthracite to United States Armed Forces in Europe. 

Apparent consumption, natural gas (international): The total of an individual nation's dry natural gas production plus 

imports less exports. 

Apparent consumption, petroleum (international): Consumption that includes internal consumption, refineryfuel and 

loss, and bunkering. For countries in the Organization for Economic Cooperation and Development (OECD), apparent 

consumption is derived from refined product output plus refined product imports minus refined product exports plus refined 

product stock changes plus other oil consumption (such as direct use of crude oil). For countries outside the OECD, 

apparent consumption is either a reported figure or is derived from refined product output plus refined product imports 

minus refined product exports, with stock levels assumed to remain the same. Apparent consumption also includes, where 

available, liquefied petroleum gases sold directlyfrom natural gas processing plants for fuel or chemical uses. 

Apparent power: The product of the voltage (in volts) and the current (in amperes). It comprises both active and reactive 

power. It is measured in "volt-amperes" and often expressed in "kilovolt-amperes" (kVA) or "megavolt-amperes" (M ). See 

Power, Reactive Power, Real Power. 

Appliance: Apiece of equipment, commonly powered by electricity, used to perform a particular energy-driven function. 

Examples of common appliances are refrigerators, clothes washers and dishwashers, conventional ranges/ovens and 

microwave ovens, humidifiers and dehumidifiers, toasters, radios, and televisions. Note: Appliances are ordinarily selfcontained with respect to their function. Thus, equipment such as central heating and air conditioning systems and water 

heaters, which are connected to distribution systems inherent to their purposes, are not considered appliances. 

Appliance efficiency index: A relative comparison of trends in new-model efficiencies for major appliances and energyusing equipment. The base year for relative comparisons was 1972(1972=100). Efficiencies for each year were eff 

t model types that were weighted by their market shares. 

Appliance efficiency standards: The National Appliance Energy Conservation Act of 1987 established minimum efficiency 

standards for major home appliances, including furnaces, central and room air conditioners, refrigerators, freezers, water 

heaters, dishwashers, and heat pumps. Most of the standards took effect in 1990.The standards for clothes washers, 

dishwashers, and ranges took effectin 1988, because they required only minor changes in product design, such as 

eliminating pilot lights and requiring cold water rinse options.The standards for central air conditioners and furnaces took 

effect in1992, because it took longer to redesign these products. Appliance efficiency standards for refrigerators took effect 

in 1993. 

ARA: Amsterdam-Rotterdam-Antwerp 

Arbitrage: The simultaneous purchase and sale of identical or similar assets across two or more markets in order to profit 

from a tern porary price discrepancy. 

Aromatics: Hydrocarbons characterized by unsaturated ring structures of carbon atoms. Commercial petroleum aromatics 

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are benzene, toluene, and xylene (BTX). 

As received coal: Coal in the condition as received by the user. 

As-received condition or as-received basis (coal): Coal in the condition as received by the consumer or the laboratory 

analyzing the coal. 

Asbestos: Agroup of naturally occurring minerals that separate into long, thin fibers. Asbestos was used for manyyears to 

insulate and fireproof buildings. In the 1989 CBECS, information on asbestos in buildings was collected (Section R of the 

Buildings Questionnaire) for the U.S. Environmental Protection Agency (EPA). Asbestos treatment methods include 

removal, encapsulation or sealing, and enclosure behind a permanent barrier. 

Ash: Impurities consisting of silica, iron, alumina, and other noncombustible matter that are contained in coal. Ash 

increases the weight of coal, adds to the cost of handling, and can affect its burning characteristics Ash content is 

measured as a percent byweight of coal on an "as received" or a "dry' (moisture-f Ily part of a laboratory analysis) 

basis. 

Asphalt: Adark brown-to-black cement-like material obtained by petroleum processing and containing bitumens as the 

predominant component; used primarily for road construction. It includes crude asphalt as well as the following finished 

products: cements, fluxes, the asphalt content of emulsions (exclusive of water), and petroleum distillates blended with 

asphalt to make cutback asphalts. Note: The conversion factor for asphalt is 5.5 barrels per short ton. 

Asphalt (refined): See Asphalt. 

Assembly identifier: A unique string of alphanumeric characters that identifies an assembly, bundle, or canister for 

aspecific reactor in which it has been irradiated. 

Assembly type: Each assembly is characterized by a fabricator, rod-array size, and model type. An eight-digit assembly 

type code is assigned to each assemblyty tain distinguishing characteristics, such as the number of rods 

per assembly, fuel roddiameter, cladding type, materials used in fabrication, and other design features. 

Assessment work: The annual or biennial work performed on a mining claim (or claims), after claim location and before 

patent, to benefit or develop the claim and to protect it from relocation by third parties. 

Assistance for heating in winter: Assistance from the Low-Income Home EnergyAssistance Program (LIHEAP). The 

purpose of LIHEAP is to assist eligible households to meet the costs of home energy, i.e., a source of heating or cooling 

residential buildings. 

Assistance for weatherization of residence: The household received services free, or at a reduced cost, from the Federal, 

State, or local Government. Any of the following services could have been received: * Insulation in the attic, outside wall, or 

basement/crawlspace below the floor of the house * Insulation around the hot water heater * Repair of broken windows or 

doors to keep out the cold or hot weather * Weather stripping or caulking around any windows or doors to the outside * 

Storm doors or windows added * Repair of broken furnace * Furnace tune-up and/or modifications * Other home energysaving devices. 

Associated natural gas: See Associated-dissolved natural gas and Natural gas. 

Associated-dissolved natural gas: Natural gas that occurs in crude oil reservoirs either as free gas (associated) or as gas 

in solution with crude oil (dissolved gas). Also see Natural gas. 

ASTM: American Societyfor Testing and Materials 

at wt: The abbreviation for atomic weight. 

Atmospheric crude oil distillation: The refining process of separating crude oil components at atmospheric pressure by 

heating to temperatures of about 600 degrees to 750 degrees Fahrenheit (depending on the nature of the crude oil and 

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desired products) and subsequent condensing of the fractions by cooling. 

Auger mine: A surface mine in which the coal bed is removed by means of a large diameter drill. Usually operated only 

when the overburden becomes too thick for economical strip mining. 

Authorized cash distribution to municipality: The authorized cash distributions to the municipality from the earned surplus 

of the utility department. 

Automatic set-back or clock thermostat: Athermostat that can be set to turn the heating/cooling system off and on at 

certain predetermined times. 

Automobile and truck classifications: Vehicle classifications for automobiles and light duty trucks were obtained from the 

EPA (Env I Protection Agency) mileage guide book. Almost every year there are small changes in the 

classifications, therefore the categories will change accordingly. The EPA mileage guide can be found at any new car 

dealership. 

Auxiliary generator: A generator at the electric plant site that provides power for the operation of the electrical generating 

equipment itself, including related demands such as plant lighting, during periods when the electric plant is not operating 

and power is unavailable from the grid. A black start generator used to start main central station generators is considered to 

be an auxiliary generator. 

Available but not needed capability: Net capabilityof main generating units that are operable but not considered 

necessary to carry load and cannot be connected to load within 30 minutes. 

Average Annual Percent Change (Coal): The average annual percent change over a period of several years that is 

calculated by taking the nth root [where n is the number of years in the period of interest] of the result of the current year's 

value divided by the value of the first year of the period; this result then has 1 (one) subtracted from it and that result is then 

multiplied by 100. 

1)X100 Where VO = the value for the base period. 

Vn= the value for the n th period. 

n = the number of periods. 

Average daily production: The ratio of the total production at a mining operation to the total number of production days 

worked at the operation. 

Average delivered price: The weighted average of all contract price commitments and market price settlements in a 

delivery year. 

Average household energy expenditures: A ratio estimate defined as the total household energy expenditures divided by 

the total number of households. 

Average mine price: The ratio of the total value of the coal produced at the mine to the total production tonnage. 

Average production per miner per day: The product of the average production per miner per hour at a mining operation 

and the average length of a production shift at the operation. 

Average production per miner per hour: The ratio of the total production at a mining operation to the total direct labor 

hours worked at the operation. 

Average revenue per kilowatthour: The average revenue per kilowatthour of electricity sold by sector (residential, 

commercial, industrial, or other) and geographic area (State, Census division, and national) is calculated by dividing the 

total monthly revenue by the corresponding total monthly sales for each sector and geographic area. 

Average stream flow: The rate, usually expressed in cubic feet per second, at which water passes a given point in a 

stream over a set period of time. 

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Average vehicle fuel consumption: A ratio estimate defined as total gallons of fuel consumed by all vehicles divided by (1) 

the total number of vehicles (for average fuel consumption per vehicle) or (2) the total number of households (for average 

fuel consumption per household). 

Average vehicle miles traveled: A ratio estimate defined as total miles traveled by all vehicles, divided by. (1) the total 

number of vehicles (for average miles traveled per vehicle) or (2) the total number of households (for average miles traveled 

per household). 

Average water conditions: The amount and distribution of precipitation within a drainage basin and the run off conditions 

present as determined by reviewing the area water supply records over a long period of time. 

Aviation gasoline (finished): A com plex m ixture of relatively volatile hydrocarbons with or without small quantities of 

additives, blended to form a fuel suitable for use in aviation reciprocating engines. Fuel specifications are provided in ASTM 

Specification D 910 and Military Specification MIL-G-5572. Note: Data on blending components are not counted in data on 

finished aviation gasoline. 

Aviation gasoline blending components:: Naphthas that will be used for blending or compounding into finished aviation 

gasoline (e.g., straight run gasoline, alkylate, reformate,benzene, toluene, and xylene). Excludes oxygenates (alcohols, 

ethers), butane, and pentanes plus. Oxygenates are reported as other hydrocarbons, hydrogen, and oxygenates. 

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Glossary 

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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

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Backup fuel: In a central heat pump system, the fuel used in the furnace that takes over the space heating when the 

outdoor tern perature drops below that which is feasible to operate a heat pump. 

Backup generator: A generator that is used only for test purposes, or in the event of an emergency, such as a shortage of 

power needed to meet customer load requirements. 

Backup power: Electric energy supplied by a utilityto replace power and energy lost during an unscheduled equipment 

outage. 

Balancing authority (electric): The responsible entitythat integrates resource plans ahead of time, maintains loadinterchange-generation balance within a Balancing Authority Area, and supports Interconnection frequency in real time. 

NERC definition 

Balancing item: Represents differences between the sum of the components of natural gas supply and the sum of the 

components of natural gas disposition. These differences maybe due to quantities lost or to the effects of data reporting 

problems. Reporting problems include differences due to the net result of conversions off low data metered at varying 

temperature and pressure bases and converted to a standard temperature and pressure base; the effect of variations in 

corn pany accounting and billing practices; differences between billing cycle and calendar period time frames; and 

imbalances resulting from the merger of data reporting systems that vary in scope, format, definitions, and type of 

respondents. 

Barrel: A unit of volume equal to 42 U.S. gallons. 

Barrels per calendar day: The amount of input that a distillation facility can process under usual operating conditions. The 

amount is expressed in terms of capacity during a 24-hour period and reduces the maximum processing capability of all 

units at the facility under continuous operation (seeBarrels per Stream Day) to account for the following limitations that may 

delay, interrupt, or slow down production. 1. the capability of downstream processing units to absorb the output of crude oil 

processing facilities of a given refinery. No reduction is necessary for intermediate streams that are distributed to other than 

downstream facilities as part of a refinery's normal operation; 2. the types and grades of inputs to be processed; 3. the 

types and grades of products expected to be manufactured; 4. the environmental constraints associated with refinery 

operations; 5. the reduction of capacity for scheduled downtime due to such conditions as routine inspection, maintenance, 

repairs, and turnaround; and 6. the reduction of capacity for unscheduled downtime due to such conditions as mechanical 

problems, repairs, and slowdowns. 

Barrels per stream day: The maximum number of barrels of input that a distillation facility can process within a 24-hour 

period when running at full capacity under optimal crude and product slate conditions with no allowance for downtime. 

Base (cushion) gas: The volume of gas needed as a permanent inventory to maintain adequate reservoir pressures and 

deliverability rates throughout the withdrawal season. All native gas is included in the base gas volume. 

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Base bill: A charge calculated by taking the rate from the appropriate electric rate schedule and applying it to the level of 

consumption. 

Base load: The minimum amount of electric power delivered or required over a given period of time at a steady rate. 

Base load capacity: The generating equipment normally operated to serve loads on an around-the-clock basis. 

Base load plant: A plant, usually housing high-efficiency steam-electric units, which is normally operated to take all or part 

of the minimum load of a system, and which consequently produces electricity at an essentially constant rate and runs 

continuously. These units are operated to maximize system mechanical and thermal efficiency and minimize system 

operating costs. 

Base period: The period of time for which data used as the base of an index number, or other ratio, have been collected. 

This period is frequently one of a year but it maybe as short as one day or as long as the average of a group of years. The 

length of the base period is governed by the nature of the material under review, the purpose for which the index number (or 

ratio) is being compiled, and the desire to use a period as free as possible from abnormal influences in order to avoid bias. 

Base rate: Afixed kilowatthour charge for electricity consumed that is independent of other charges and/or adjustments. 

Baseboard heater: As a type of heating equipment, a system in which either electric resistance coils or finned tubes 

carrying steam or hot water are mounted behind shallow panels along baseboards. Baseboards rely on passive convection 

to distribute heated air in the space. Electric baseboards are an example of an "Individual Space Heater." 

bbl: The abbreviation for barrel(s). 

bbl/d: The abbreviation for barrel(s) per day. 

bbl/sd: The abbreviation for barrel(s) per stream day. 

bcf: The abbreviation for billion cubic feet. 

Benzene (C6H6): An aromatic hydrocarbon present in small proportion in some crude oils and made commerciallyfrom 

petroleum by the catalytic reforming of naphthenes in petroleum naphtha. Also made from coal in the manufacture of coke. 

Used as a solvent in the manufacture of detergents, synthetic fibers, petrochemicals, and as a component of high-octane 

gasoline. 

Bi-fuel vehicle: A motor vehicle that operates on two different f Is, but not on a mixture of the fuels. Each fuel is stored in a 

separate tank. 

Bilateral agreement: Awritten statement signed bytwo parties that specifies the terms for exchanging energy. 

Bilateral energy transaction: Atransaction between two willing parties who enter into a physical or financial agreement to 

trade energy com modities. Bilateral transactions entail reciprocal obligations and can involve direct negotiations or deals 

made through brokers. 

Billing period: The time between meter readings. It does not refer to the time when the bill was sent or when the payment 

was to have been received. In some cases, the billing period is the same as the billing cycle that corresponds closely 

(within several days) to meter-reading dates. For fuel oil and LPG, the billing period is the number of days between fuel 

deliveries. 

Biodiesel: Afuel t Ily made from soybean, canola, or other vegetable oils; animal fats; and recycled grease. It can serve 

as a substitute for petroleum-derived diesel or distillate fuel. For EIA reporting, it is a fuel composed of mono-alkyl esters of 

long chain fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTM 

(American Society for Testing materials) D 6751. 

Biofuels: Liquid fuels and blending components produced from biomass feedstocks, used primarilyfor transportation. 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

Biogenic: Produced by biological processes of living organisms. Note: EIA uses the term "biogenic" to refer only to organic 

nonfossil material of biological origin. 

Biogenic emissions: Emissions that are naturally occurring and are not significantly affected by human actions or activity. 

Biomass: Organic nonfossil material of biological origin constituting a renewable energy source. 

Biomass gas: A medium Btu gas containing methane and carbon dioxide, resulting from the action of microorganisms on 

organic materials such as a landfill. 

Biomass waste: Organic non-fossil material of biological origin that is a byproduct or a discarded product. Biomass waste 

includes municipal solid waste from biogenic sources, landfill gas, sludge waste, agricultural crop byproducts, straw, and 

other biomass solids, liquids, and gases; but excludes wood and wood-derived fuels (including black liquor), biofuels 

feedstock, biodiesel, and fuel ethanol. Note: EIA biomass waste data also include energy crops grown specifically for 

energy production, which would not normally constitute waste. 

Biomass-based diesel fuel: Biodiesel and other renewable diesel f I or diesel fuel blending components derived from 

biomass, but excluding renewable diesel f I coprocessed with petroleum feedstocks. 

Bitumen: A naturally occurring viscous mixture, mainly of hydrocarbons heavier than pentane, that may contain sulphur 

compounds and that, in its natural occurring viscous state, is not recoverable at a commercial rate through a well. 

Bituminous coal: A dense coal, usually black, sometimes dark brown, often with well-defined bands of bright and dull 

material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and 

power applications in manufacturing and to make coke. Bituminous coal is the most abundant coal in active U.S. mining 

regions. It Ily is less than 20 percent. The heat content of bituminous coal ranges from 21 to 30 

million Btu per ton on a moist, mineral-matter-free basis. The heat content of bituminous coal consumed in the United 

States averages 24 million Btu per ton, on the as-received basis (i.e., containing both inherent moisture and mineral 

matter). 

Black liquor: A by product of the paper production process, alkaline spent liquor, that can be used as a source of energy. 

Alkaline spent liquor is removed from the digesters in the process of chemically pulping wood. After evaporation, the 

residual "black" liquor is burned as a fuel in a recoveryfurnace that permits the recovery of certain basic chemicals. 

Black lung benefits: In the content of the coal operation statement of income, this term refers to all payments, including 

taxes, made by the company attributable to Black Lung. 

Blast furnace: Afurnace in which solid fuel (coke) is burned with an air blast to smelt ore. 

Blast-furnace gas: The waste combustible gas generated in a blast furnace when iron ore is being reduced with coke to 

metallic iron. It is commonly used as a fuel within steel works. 

Blending components: See Motor gasoline blending components. 

Blending plant: A facility that has no refining capability but is either capable of producing finished motor gasoline through 

mechanical blending or blends oxygenates with motor gasoline. 

Block-rate structure: An electric rates schedule with a provision for charging a different unit cost for various increasing 

blocks of demand for energy. A reduced rate maybe charged on succeeding blocks. 

BLS: Bureau of Labor Statistics within the U.S. Department of Labor 

BOE: Barrels of Oil Equivalent (used internationally) 

Boiler: A device for generating steam for power, processing, or heating purposes; or hot water for heating purposes or hot 

water supply. Heat f ternal combustion source is transmitted to a fluid contained within the tubes found in the 

boiler shell. This fluid is delivered to an end-use at a desired pressure, temperature, and quality. 

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Boiler fuel: An energysource to produce heat that is transferred to the boiler vessel in order to generate steam orhot water. 

Fossil f I is the primary energy source used to produce heat for boilers. 

Boiling-water reactor (B ): Alight-water reactor in which water, used as both coolant and moderator, is allowed to boil in 

the core. The resulting steam can be used directly to drive a turbine. 

Bonded petroleum imports: Petroleum imported and entered into Customs bonded storage. These imports are not 

included in the import statistics until they are (1) withdrawn from storage free of duty for use as fuel for vessels and aircraft 

engaged in international trade; or (2) withdrawn from storage with duty paid for domestic use. 

Bone coal: Coal with a high ash content; it is dull in appearance, hard, and compact. 

Book value: The portion of the carrying value (other than the portion associated with tangible assets) prorated in each 

accounting period, for financial reporting purposes, to the extracted portion of an economic interest in a wasting natural 

resource. 

Booked costs: Costs allocated or assigned to inter-departmental or intra company transactions, such as on-system or 

synthetic natural gas (SNG) production and company-owned gas used in gas operations and recorded in company books 

or records for accounting and/or regulatory purposes. 

Borderline customer: A customer located in the service area of one utility, but supplied bya neighboring utilitythrough an 

arrangement between the utilities. 

Bottled gas: SeeLiquefied petroleum gases. 

Bottled gas, LPG, or propane: Anyfuel gas supplied to a building in liquid form, such as liquefied petroleum gas, propane, 

or butane. It is usuallydelivered bytank truck and stored near the building in a tank or cylinder until used. 

Bottom ash: Residue mainlyfrom the coal burning process that falls to the bottom of the boiler for removal and disposal. 

Bottom-hole contribution: A payment (either in cash or in acreage) that is required by agreement when a test well is drilled 

to a specified depth regardless of the outcome of the well and that is made in exchange for well and evaluation data. 

Bottoming cycle: Awaste-heat recovery boiler recaptures the unused energy and uses it to produce steam to drive a 

steam turbine generator to produce electricity. 

bp: The abbreviation for boiling point. 

Branded product: A refined petroleum product sold bya refiner with the understanding that the purchaser has the right to 

resell the product under a trademark, trade name, service mark, or other identifying symbol or names owned by such 

refiner. 

Break-even cutoff grade: The lowest grade of material that can be mined and processed considering all applicable costs, 

without incurring a loss or gaining a profit. 

Breccia: A coarse-grained clastic rock, composed of angular broken rock fragments held together bya mineral cement or 

in a fine-grained matrix 

Breeder reactor: A reactor that both produces and consumes fissionable fuel, especially one that creates more fuel than it 

consumes. The new fissionable material is created bya process known as breeding, in which neutrons from fission are 

captured in fertile materials. 

Breeze: The fine screenings from crushed coke. Usually breeze will pass through a 1/2-inch or 3/4-inch screen opening. It 

is most often used as a fuel source in the process of agglomerating iron ore. 

British thermal unit: The quantity of heat required to raise the temperature of 1 pound of liquid water by 1 degree 

Fahrenheit at the temperature at which water has its greatest density (approximately 39 degrees Fahrenheit). 

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Btu: The abbreviation forBritish Thermal Unit(s). 

Btu conversion factor: Afactor for converting energy data between one unit of measurement and British thermal units 

(Btu). Btu conversion factors are generally used to convert energy data from physical units of measure (such as barrels, 

cubic feet, or short tons) into the energy-equivalent measure of Btu. (See 

http://www.eia.gov/totalenergy/data/monthly/pdf/secl3.pdfforfurther information on Btu conversion factors.) 

Btu per cubic foot: The total heating value, expressed in Btu, produced by the combustion, at constant pressure, of the 

amount of the gas that would occupy a volume of 1 cubic foot at a temperature of 60 degrees F if saturated with water vapor 

and under a pressure equivalent to that of 30 inches of mercury at 32 degrees F and under standard gravitational force 

(980.665 cm. per sec. squared) with air of the same temperature and pressure as the gas, when the products of 

combustion are cooled to the initial temperature of gas and air when the water formed by combustion is condensed to the 

liquid state.(Sometimes called gross heating value or total heating value.) 

BTX: The acronym for the commercial petroleum aromatics-- benzene, toluene, and xylene. 

Budget plan: An agreement between the household and the utility company or fuel supplier that allows the household to 

paythe same amount for fuel for each month for a number of months. 

Building shell (envelope) DSM program: A DSM program that promotes reduction of energy consumption through 

improvements to the building envelope. Includes installations of insulation, weather stripping, caulking, window film, and 

window replacement. (Also seeDSM, Demand-Side Management Programs.) 

Building shell conservation feature: A building feature designed to reduce energy loss or gain through the shell or 

envelope of the building. Data collected by EIA on the following specific building shell energy conservation features: roof, 

ceiling, or wall insulation; storm windows or double- or triple-paned glass (multiple glazing); tinted or reflective glass or 

shading films; exterior or interior shadings or awnings; and weather stripping or caulking. (SeeRoof or Ceiling Insulation, 

Wall Insulation, Reflective or Shading Glass orFilm, Storm Window or Triple-Paned Glass, Building Shell (Envelope), and 

Weather Stripping or Caulking.) 

Built-in electric units: An individual-resistance electric-heating unit that is permanently installed in the floors, walls, 

ceilings, or baseboards and is part of the electrical installation of the building. Electric-heating devices that are plugged into 

an electric socket or outlet are not considered built in. (Also seeHeating Equipment.) 

Bulk power transactions: The wholesale sale, purchase, and interchange of electricity among electric utilities. Bulk power 

transactions are used by electric utilities for many different aspects of electric utility operations, from maintaining load to 

reducing costs. 

Bulk sales: Wholesale sales of gasoline in individual transactions which exceed the size of a truckload. 

Bulk station: Afacility used primarily for the storage and/or marketing of petroleum products, which has a total bulk storage 

capacity of less than 50,000 barrels and receives its petroleum products bytank car or truck. 

Bulk terminal: Afacility used primarilyfor the storage and/or marketing of petroleum products, which has a total bulk 

storage capacity of 50,000 barrels or more and/or receives petroleum products bytanker, barge, or pipeline. 

Bundled utility service (electric): A m eans of operation whereby energy, transmission, and distribution services, as well 

as ancillary and retail services, are provided by one entity. 

Bunker fuels: Fuel supplied to ships and aircraft, both domestic and foreign, consisting primarily of residual and distillate 

fuel oil for ships and kerosene-based jet fuel for aircraft. The term "international bunker fuels" is used to denote the 

consumption off I for international transport activities. Note: For the purposes of greenhouse gas emissions inventories, 

data on emissions from combustion of international bunker fuels are subtracted from national emissions totals. 

Historically, bunker fuels have meant onlyship fuel. 

Burn days: The number of days the station could continue to operate by burning coal already on hand assuming no 

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additional deliveries of coal and an average consumption rate. 

Burnup: Amount of thermal energy generated per unit mass of fuel, expressed as Gigawatt-Days Thermal per Metric Ton of 

Initial Heavy Metal (GWDT/MTIHM), rounded to the nearest gigawatt day. 

Bus: An electrical conductor that serves as a common connection for two or more electrical circuits. 

Butane (C4Hig): A normally gaseous straight-chain or branch-chain hydrocarbon extracted from hydrocarbon extracted 

from natural gas or refinerygas streams. It includes isobutane and normal butane and is designated in ASTM Specification 

D1835 and Gas Processors Association Specifications for commercial butane. 

Butylene (C4H8): An olefinic hydrocarbon recovered from refinery processes. 

Buy-back oil: Crude oil acquired from a host government whereby a portion of the government's ownership interest in the 

crude oil produced in that country mayor should be purchased bythe producing firm. 

B ling-Water Reactor 

Bypassed footage: Bypassed footage is the footage in that section of hole that is abandoned as the result of remedial 

sidetrack drilling operations. 

B tional product resulting from the feedstock use of energy or the processing of nonenergy 

materials. For example, the more common byproducts of coke ovens are coal gas, tar, and a mixture of benzene, toluene, 

and xylenes (BTX). 

ABCDEFGHIJKLMNOPQRSTUVWXYZ 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

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Glossary 

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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

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C 

C/gal: Cents per gallon 

C4H: A mixture of light hydrocarbons that have the general formula C4Hn, where n is the number of hydrogen atoms per 

molecule. Examples include butane (C4F110) and butylene (C41-18). 

CAFE: Corporate Average Fuel Economy 

Calcination: A process in which a material is heated to a high temperature without fusing, so that hydrates, carbonates, or 

other compounds are decomposed and the volatile material is expelled. 

Calcium sulfate: Awhite crystalline salt, insoluble in water. Used in Keene's cement, in pigments, as a paper filler, and as 

a drying agent. 

Calcium sulfite: Awhite powder, soluble in diluted sulf . Used in the sulf 

Ip. 

California power exchange: A State-chartered, non-profit corporation which provides day-ahead and hour-ahead markets 

for energy and ancillary services in accordance with the power exchange tariff. The power exchange is a scheduling 

coordinator and is independent of both the independent system operator and all other market participants. 

Canadian deuterium uranium reactor (CANDU): Uses heavy water or deuterium oxide (020), rather than light water (H20), 

as the coolant and moderator. Deuterium is an isotope of hydrogen that has a different neutron absorption spectrum from 

that of ordinary hydrogen. In a deuterium-moderated-reactor, f I made from natural uranium (0.71U-235) can sustain a 

chain reaction. 

Cannel coal: A compact, tough variety of coal, originating from organic spore residues, that is non-caking, contains a high 

percentage of volatile matter, ignites easily, and burns with a luminous smokyflame. 

Capable of being fueled: Avehicle is capable of being fueled by a particular fuel(s) if that vehicle has the engine 

components in place to make operation possible on the fuel(s). The vehicle does not necessarily have to run on the fuel(s) 

in order for that vehicle to be considered capable of being fueled by the fuel(s). For example, a vehicle that is equipped to 

operate on either gasoline or natural gas but normally operates on gasoline is considered to be capable of being fueled by 

gasoline and natural gas. 

Capacity: SeeGenerator capacityand (installed) Generator name plate capacity. 

Capacity (purchased): The amount of energy and capacity available for purchase from outside the system. 

Capacity charge: An element in a two-part pricing method used in capacity transactions (energy charge is the other 

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element). The capacity charge, sometimes called Demand Charge, is assessed on the amount of capacity being 

purchased. 

Capacity factor: The ratio of the electrical energy produced by a generating unit for the period of time considered to the 

electrical energy that could have been produced at continuous full power operation during the same period. 

Capacity transaction: The acquisition of a specified quantity of generating capacity from another utility for a specified 

period of time. The utility selling the power is obligated to make available to the buyer a specified quantity of power. 

Capacity utilization: Capacity utilization is corn puted by dividing production by productive capacity and multiply 

Capital cost: The cost of field development and plant construction and the equipment required for industr tions. 

Capital stock: Property, plant and equipment used in the production, processing and distribution of energy resources. 

Captive coal: Coal produced to satisfy the needs of the mine owner, or of a parent, subsidiary, or other affiliate of the mine 

owner (for example, steel companies and electricitygenerators), rather than for open market sale. 

Captive refinery MTBE plants: MTBE (methylter I ether) production facilities primarily located within refineries. 

These integrated refinery units produce IVITBE f Fluid Cat Cracker isobutylene with production dedicated to internal 

gasoline blending requirements. 

Captive refinery oxygenate plants: Oxygenate production facilities located within or adjacent to a refinery complex 

CARB: California Air Resources Board 

Carbon black: An amorphous form of carbon, produced commercially bythermal or oxidative decomposition of 

hydrocarbons and used principally in rubber goods, pigments, and printer's ink. 

Carbon budget: The balance of the exchanges (incomes and losses) of carbon between carbon sinks (e.g., atmosphere 

and biosphere) in the carbon cycle. Also seeCarbon cycleand Carbon sink. 

Carbon cycle: All carbon sinks and exchanges of carbon from one sink to another by various chemical, physical, 

geological, and biological processes. Also seeCarbon sink. 

Carbon dioxide (CO2): A colorless, odorless, non-poisonous gas that is a normal part of Earth's atmosphere. Carbon 

dioxide is a product of fossil-fuel combustion as well as other processes. It is considered a greenhouse gas as it traps 

heat (infrared energy) radiated by the Earth into the atmosphere and thereby contributes to the potential for global warming. 

The global warming potential (GWP) of other greenhouse gases is measured in relation to that of carbon dioxide, which by 

international scientific convention is assigned a value of one (1). Also seeGlobal warming potential (GWP) and 

Greenhouse gases. 

Carbon dioxide equivalent: The amount of carbon dioxide byweight emitted into the atmosphere that would produce the 

same estimated radiative forcing as a given weight of another radiatively active gas. Carbon dioxide equivalents are 

computed by multiply (for example, methane)by its estimated global warming 

potential (which is 21 for methane)."Carbon equivalent units" are defined as carbon dioxide equivalents multiplied bythe 

carbon content of carbon dioxide (i.e., 12/44). 

Carbon flux: SeeCarbon budget. 

Carbon intensity: The amount of carbon by weight emitted per unit of energy consumed. A common measure of carbon 

intensity is weight of carbon per British thermal unit (Btu) of energy. When there is only one fossil f I under consideration, 

the carbon intensity and the emissions coefficient are identical. When there are several f Is, carbon intensity is based on 

their combined emissions coefficients weighted bytheir energy consumption levels. Also seeEmissions coefficientand 

Carbon output rate. 

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Carbon output rate: The amount of carbon byweight per kilowatthour of electricity produced. 

Carbon sequestration: The fixation of atmospheric carbon dioxide in a carbon sink through biological or physical 

processes. 

Carbon sink: A reservoir that absorbs or takes up released carbon from another part of the carbon cycle. The four sinks, 

which are regions of the Earth within which carbon behaves in a systematic manner, are the atmosphere, terrestrial 

biosphere (usually including freshwater systems), oceans, and sediments (including fossil f Is). 

Carbon stocks: The quantity of carbon stored in biological and physical systems including: trees, products of harvested 

trees, agricultural crops, plants, wood and paper products and other terrestrial biosphere sinks, soils, oceans, and 

sedimentary and geological sinks. 

Carburetor: A fuel delivery device for producing a proper mixture of gasoline vapor and air and for delivering it to the intake 

manifold of an internal combustion engine. Gasoline is gravity-fed from a reservoir bowl into a throttle bore, where it is 

allowed to evaporate into the stream of air being inducted bythe engine. Also seeDiesel Fuel System and Fuel Injection. 

Carrying costs: Costs incurred in order to retain exploration and property rights after acquisition but before production has 

occurred. Such costs include legal costs for title defense, ad valorem taxes on nonproducing mineral properties, shut-in 

royalties, and delay rentals. 

Cash and carry: Kerosene, fuel oil, or bottled gas (tank or propane) purchased with cash, by check, or by credit card and 

taken home by the purchaser. The purchaser provides the container or pays extra for the container. 

Casinghead gas (or oil well gas): Natural gas produced along with crude oil from oil wells. It contains either dissolved or 

associated gas or both. 

Cast silicon: Crystalline silicon obtained by pouring pure molten silicon into a vertical mold and adjusting the temperature 

gradient along the mold volume during cooling to obtain slow, vertically advancing crystallization of the silicon. The 

polycrystalline ingot thus formed is composed of large, relatively parallel, interlocking crystals. The cast ingots are sawed 

into wafers for further fabrication into photovoltaic cells. Cast silicon wafers and ribbon silicon sheets fabricated into cells 

are usually referred to aspolycrystalline photovoltaic cells. 

Catalyst coke: In many catalytic operations (e.g., catalytic cracking), carbon is deposited on the catalyst, thus deactivating 

the catalyst. The catalyst is reactivated by burning off the carbon, which is used as a fuel in the refining process. This carbon 

or coke is not recoverable in a concentrated form. 

Catalytic converter: A device containing a catalyst for converting automobile exhaust into mostly harmless products. 

Catalytic cracking: The refining process of breaking down the larger, heavier, and more complex hydrocarbon molecules 

into simpler and lighter molecules. Catalytic cracking is accomplished by the use of a catalytic agent and is an effective 

process for increasing the yield of gasoline from crude oil. Catalytic cracking processes fresh feeds and recycled feeds. 

Catalytic hydrocracking: A refining process that uses hydrogen and catalysts with relatively low temperatures and high 

pressures for converting middle boiling or residual material to high octane gasoline, reformer charge stock, jet f I, and /or 

high grade fuel oil. The process uses one or more catalysts, depending on product output, and can handle high sulf feed 

stocks without prior desulf zation. 

Catalytic hydrotreating: A refining process for treating petroleum fractions from atmospheric or vacuum distillation units 

(e.g., naphthas, middle distillates, reformer feeds, residual f I oil, and heavy gas oil) and other petroleum (e.g., cat cracked 

naphtha,coker naphtha, gas oil, etc.) in the presence of catalysts and substantial quantities of hydrogen. Hydrotreating 

includes desulfurization, removal of substances (e.g., nitrogen compounds) that deactivate catalysts, conversion of olefins 

to paraffins to reduce gum formation in gasoline, and other processes to upgrade the quality of the fractions. 

Catalytic reforming: A refining process using controlled heat and pressure with catalysts to rearrange certain hydrocarbon 

molecules, there by converting paraffinic and naphthenic type hydrocarbons (e.g., low octane gasoline boiling range 

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ftions) into petrochemical feedstocks and higher octane stocks suitable for blending into finished gasoline. Catalytic 

reforming is reported in two categories. They are: 

• Low Pressure. A processing unit operating at less than 225 pounds per square inch gauge (PSIG) measured at the 

outlet separator. 

• High pressure. A processing unit operating at either equal to or greater than 225 pounds per square inch gauge 

(PSIG) measured at the outlet separator. 

CBOB: conventional gasoline blendstock for oxygenate blending 

CDD: SeeCooling degree-days. 

Cells: Refers to the un-encapsulated semi-conductor components of the module that convert the solar energy to electricity. 

Cells to OEM (non-PV): Cells shipped to non-photovoltaic original equipment manufacturers such as boat manufacturers, 

car manufacturers, etc. 

Census division: Anyof nine geographic areas of the United States as defined bythe U.S. Department of Commerce, 

Bureau of the Census. The divisions, each consisting of several States, are defined as follows: 

• New England: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont; 

• Middle Atlantic: New Jersey, New York, and Pennsylvania; 

• E I: Illinois, Indiana, Michigan, Ohio, and Wisconsin; 

• West North Central: Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota; 

• South Atlantic: Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, 

and West Virginia; 

• East South Central: Alabama, Kentucky, Mississippi, and Tennessee; 

• West South Central: Arkansas, Louisiana, Oklahoma, and Texas; 

• Mountain: Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, and Wyoming; 

• Pacific: Alaska, California, Hawaii, Oregon, and Washington. 

Note: Each division is a sub-area within a broader Census Region. For the relationship between Regions and 

divisions, seeCensus Region/division.In some cases, the Pacific division is subdivided into the Pacific Contiguous 

area (California, Oregon, and Washington)and the Pacific Noncontiguous area (Alaska and Hawaii). 

Census Region: Any of four geographic areas of the United States as defined bythe U.S. Department of Commerce, 

Bureau of the Census. The Regions, each consisting of various States selected according to population size and physical 

location, are defined as follows: 

• Northeast: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode 

Island, and Vermont. 

• South: Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, 

Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia. 

• Midwest: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South 

Dakota, and Wisconsin. 

• West: Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, 

Washington, and Wyoming. 

Note: Each region comprises two or three sub-areas called Census divisions. For the relationship between Regions 

and divisions, seeCensus Region/division. 

Census Region/division: An hierarchical organization of the United States according to geographic areas and sub-areas 

as follows: 

Northeast Region: New England division and Middle Atlantic division 

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South Region: South Atlantic division, East South Central division and West South Central division 

Midwest Region: East North Central division and West North Centr I division 

West Region: Mountain division and Pacific division 

Note: In some cases, the Pacific division is subdivided into the Pacific Contiguous area (California, Oregon, and 

Washington) and the Pacific Noncontiguous area (Alaska and Hawaii). 

Central chiller: Any centrally located air conditioning system that produces chilled water in order to cool air. The chilled 

water or cold air is then distributed throughout the building, using pipes or air ducts or both. These systems are also 

commonly known as "chillers," "centrifugal chillers," "reciprocating chillers," or "absorption chillers." Chillers are generally 

located in or just outside the building they serve. Buildings receiving district chilled water are served by chillers located at 

central physical plants. 

Central cooling: Cooling of an entire building with a refrigeration unit to condition the air. Typically central chillers and duct 

work are present in the centrally cooled building. 

Central physical plant: A plant owned by, and on the grounds of, a multibuilding facility that provides district heating, district 

cooling, or electricity to other buildings on the same facility. To qualify as a central plant it must provide district heat, district 

chilled water, or electricity to at least one other building. The central physical plant may be by itself in a separate building or 

may be located in a building where other activities occur. 

Central warm air furnace: Atype of space heating equipment where a central combustor or resistance unit generally using 

gas, fuel oil, or electricity provides warm air through ducts leading to the various rooms. Heat pumps are not included in this 

category. Aforced air furnace is one in which a fan is used to force the air through the ducts. In a gravity furnace, air is 

circulated by gravity, rely I flow of warm air up and cold air down; the warm air rises through ducts and the 

cold air falls through ducts that return it to the furnace to be reheated and this completes the circulation cycle. 

Centralized water heating system: Equipment, to heat and store water for other than space heating purposes, which 

provides hot water from a single location for distribution throughout a building. A residential type tank water heater is a good 

example of a centralized water heater. 

CER LA: Comprehensive Environmental Response, Compensation, and LiabilityAct 

Certificate: Atype of permit for public convenience and necessity issued by a utility commission, which authorizes a utility 

or regulated com pany to engage in business, construct facilities, provide some services, or abandon service. 

Certificate requirement: The maximum annual volume allowed for sales to resale or direct sale customers under 

certificate authorizations by the Federal Energy Regulatory Corn mission. 

Cesspool: An underground reservoir for liquid waste, typically household sewage. 

CF: Cubic Foot 

CFC: SeeChlorofluorocarbon. 

CFS: Cubic Feet per Second 

CH4: Methane 

Chained dollars: A m easure used to express real prices. Real prices are those that have been adjusted to remove the 

effect of changes in the purchasing power of the dollar; they usually reflect buying power relative to a reference year. Prior to 

1996, real prices were expressed in constant dollars, a measure based on the weights of goods and services in a single 

year, usually a recent year. In 1996, the U.S. Department of Commerce introduced the chained-dollar measure. The new 

measure is based on the average weights of goods and services in successive pairs of years. It is "chained" because the 

second year in each pair, with its weights, becomes the first year of the next pair. The advantage of using the chained-dollar 

measure is that it is more closely related to any given period covered and is therefore subject to less distortion over time. 

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Characterization: Sampling, monitoring, and analysis activities to determine the extent and nature of contamination at a 

facility or site. Characterization provides the necessary technical information to develop, screen, analyze, and select 

appropriate clean-up techniques. 

Charge capacity: The input (feed) capacity of the refinery processing facilities. 

Chemical separation: A process for extracting uranium and plutonium from dissolved spent nuclear fuel and irradiated 

targets. The fission products that are left behind are high-level waste. Chemical separation is also known as reprocessing. 

Chlorofluorocarbon (CFC): Any of various compounds consisting of carbon, hydrogen, chlorine, and flourine used as 

refrigerants. CFCs are now thought to be harmful to the earth's atmosphere. 

CHP: Combined Heat and Power 

Christmas tree: The valves and fittings installed at the top of a gas or oil well to control and direct the flow of well fluids. 

CIF (cargo, insurance and freight): CIF refers to cargos for which the seller pays for the transportation and insurance up to 

the port of destination. 

CIF (cost, insurance, freight): This term refers to a type of sale in which the buyer of the product agrees to pay a unit price 

that includes the f.o.b. value of the product at the point of origin plus all costs of insurance and transportation. This type of a 

transaction differs from a "delivered" purchase, in that the buyer accepts the quantity as determined at the loading port (as 

certified by the Bill of Lading and Quality Report) rather than pay based on the quantity and quality ascertained at the 

unloading port. It is similar to the terms of an f.o.b. sale, except that the seller, as a service for which he is compensated, 

arranges for transportation and insurance. 

Circuit: A conductor or a system of conductors through which electric current flows. 

Circuit-mile: The total length in miles of separate circuits regardless of the number of conductors used per circuit. 

Citygate: A point or measuring station at which a distributing gas utility receives gas from a natural gas pipeline company 

or transmission system. 

CIV: customs import value 

Class rate schedule: An electric rate schedule applicable to one or more specified classes of service, groups of 

businesses, or customer uses. 

Classes of service: Customers grouped by sim ilar characteristics in order to be identified for the purpose of setting a 

common rate for electric service. Usually classified into groups identified as residential, commercial, industrial, and other. 

Clean Development Mechanism (CDM): A Kyoto Protocol program that enables industrialized countries to finance 

emissions-avoiding projects in developing countries and receive credit for reductions achieved against their own 

emissions limitation targets. Also seeKyoto Protocol. 

Climate change: A term used to refer to all forms of climatic inconsistency, but especially to significant change from one 

prevailing climatic condition to another. In some cases, "climate change" has been used synonymously with the term 

"global warming"; scientists, however, tend to use the term in a wider sense inclusive of natural changes in climate, 

including climatic cooling. 

Clinker: Powdered cement, produced by heating a properly proportioned mixture of finely ground raw materials 

(calciumcarbonate, silica, alumina, and iron oxide) in a kiln to a temperature of about 2,700 degrees Fahrenheit. 

Cloud condensation nuclei: Aerosol particles that provide a platform for the condensation of water vapor, resulting in 

clouds with higher droplet concentrations and increased albedo. 

CMSA: consolidated metropolitan statistical area 

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CNG: Compressed Natural Gas 

cnt: Cent 

CO: Carbon Monoxide 

CO control period ("seasons"): The portion of the year in which a CO nonattainment area is prone to high ambient levels 

of carbon mono)dde. This portion of the year is to be specified by the Environmental Protection Agency but is to be not less 

than 4 months in length. 

CO nonattainment area: Areas with carbon monoxide design values of 9.5 parts per million or more, generally based on 

data for 1988 and 1989. 

CO2: Carbon Dioxide 

Coal: A readilycombustible black or brownish-black rock whose composition, including inherent moisture, consists of 

more than 50 percent byweight and more than 70 percent byvolume of carbonaceous material. It is formed from plant 

remains that have been compacted, hardened, chemicallyaltered, and metamorphosed by heat and pressure over 

geologic time. 

Coal analysis: Determines the composition and properties of coal so it can be ranked and used most effectively. 

• Proximate analysis, determines, on an as-received basis, the moisture content, volatile matter (gases released 

when coal is heated), fixed carbon (solid fuel left after the volatile matter is driven off), and ash (impurities consisting 

of silica, iron, alumina, and other incombustible matter). The moisture content affects the ease with which coal can 

be handled and burned. The amount of volatile matter and fixed carbon provides guidelines for determining the 

intensity of the heat produced. Ash increases the weight of coal, adds to the cost of handling, and can cause 

problems such as clinkering and slagging in boilers and furnaces. 

• Ultimate analysis determines the amount of carbon, hydrogen, oxygen, nitrogen, and sulfur. Heating value is 

determined in terms of Btu, both on an as received basis (including moisture) and on a dry basis. 

• Agglomerating refers to coal that softens when heated and forms a hard gray coke; this coal is called caking coal. 

Not all caking coals are coking coals. The agglomerating value is used to differentiate between coal ranks and also 

is a guide to determine how a particular coal reacts in a furnace. 

• Agglutinating refers to the binding qualities of a coal. The agglutinating value is an indication of how well a coke 

made from a particular coal will perform in a blast f . It is also called a caking index. 

• Other tests include the determination of the ash softening temperature, the ash fusion temperature (the 

temperature at which the ash forms clinkers or slag), the free swelling index (a guide to a coal's coking 

characteristics), the Gray King test (which determines the suitability of coal for making coke), and the Hardgrove 

grindability index (a measure of the ease with which coal can be pulverized). In a petrographic analysis, thin sections 

of coal or highly polished blocks of coal are studied with a microscope to determine the physical composition, both 

for scientific purposes and for estimating the rank and coking potential. 

Coal bed: Abed or stratum of coal. Also called a coal seam. 

Coal bed degasification: This refers to the removal of methane or coal bed gas from a coal mine before or during mining. 

Coal briquets: Anthracite, bituminous, and lignite briquets comprise the secondary solid fuels manufactured from coal by a 

process in which the coal is partly dried, warmed to expel excess moisture, and then compressed into briquets, usually 

without the use of a binding substance. In the reduction of briquets to coal equivalent, different conversion factors are 

applied according to their origin from hard coal, peat, brown coal, or lignite. 

Coal carbonized: The amount of coal decomposed into solid coke and gaseous products by heating in a coke oven in a 

limited air supplyor in the absence of air. 

Coal chemicals: Coal chemicals are obtained from the gases and vapor recovered from the manufacturing of coke. 

Generally light oil, and gas are the basic products recovered. They are refined or processed to 

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yield a variety of chemical materials. 

Coal coke: See Coke (coal). 

Coal consumption: The quantity of coal burned for the generation of electric power (in short tons), including fuel used for 

maintenance of standbyservice. 

Coal delivered: Coal which has been delivered from the coal supplier to any site belonging to the electric power company. 

Coal exports: Amount of U.S. coal shipped to foreign destinations, as reported in the U.S. Department of Commerce, 

Bureau of Census, "Monthly Report EM 545." 

Coal f This is the exposed area from which coal is extracted. 

Coal financial reporting regions: A geographic classification of areas with coal resources which is used for financial 

reporting of coal statistics. 

• E . Consists of the Appalachian Coal Basin. The following comprise the Eastern Region: Alabama, 

eastern Kentucky, Georgia, Maryland, Mississippi, Ohio, Pennsylvania, Virginia, Tennessee, North Carolina, and 

West Virginia. 

• Midwest Region. Consists of the Illinois and Michigan Coal Basins. The following comprise the Midwest Region: 

Illinois, Indiana, Michigan, and western Kentucky. 

• Western Region. Consists of the Northern Rocky, Southern Rocky, West Coast Coal Basins and Western Interior. 

The following comprise the Western Region: Alaska, Arizona, Arkansas, California, Colorado, Idaho, Iowa, Kansas, 

Louisiana, Missouri, Montana, New Mexico, North Dakota, Oklahoma, Oregon, Texas, South Dakota, Utah, 

Washington, and Wyoming. 

Coal fines: Coal with a maximum particle size usually less than one-sixteenth inch and rarely above one-eighth inch. 

Coal gas: Substitute natural gas produced synthetically by the chemical reduction of coal at a coal gasification facility. 

Coal gasification: The process of converting coal into gas. The basic process involves crushing coal to a powder, which is 

then heated in the presence of steam and oxygen to produce a gas. The gas is then refined to reduce sulf ther 

impurities. The gas can be used as a fuel or processed further and concentrated into chemical or liquid fuel. 

Coal grade: This classification refers to coal quality and use. 

• Briquettes are made from compressed coal dust, with or without a binding agent such as asphalt. 

• Cleaned coal or prepared coal has been processed to reduce the amount of impurities present and improve the 

burning characteristics. 

• Compliance coal is a coal, or a blend of coal, that meets sulfur dioxide emission standards for air qualitywithout the 

need for flue-gas desulf zation. 

• Culm and silt are waste materials from preparation plants. In the anthracite region, culm consists of coarse rock 

fragments containing as much as 30 percent small-sized coal. Silt is a mixture of veryfine coal particles 

(approximately40 percent) and rock dust that has settled out from waste water from the plants. The terms culm and 

silt are sometimes used interchangeablyand are sometimes called refuse. Culm and silt have a heat value ranging 

from 8 to 17 million Btu per ton. 

• Low-sulfur coal generally contains 1 percent or less sulf . For air quality standards, "low sulfur coal" 

contains 0.6 pounds or less sulfur per million Btu, which is equivalent to 1.2 pounds of sulfur dioxide per million Btu. 

• Metallurgical coal (or coking coal) meets the requirements for making coke. It must have a low ash and sulf 

le of supporting the charge of iron ore and limestone in a blast furnace. A blend 

of two or more bituminous coals is usually required to make coke. 

• Pulverized coal is a coal that has been crushed to a fine dust in a grinding mill. It is blown into the combustion zone 

of a furnace and burns very rapidly and efficiently. 

• Slack coal usually refers to bituminous coal one-half inch or smaller in size. 

• Steam coal refers to coal used in boilers to generate steam to produce electricity or for other purposes. 

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• Stoker coal refers to coal that has been crushed to specific sizes (but not powdered) for burning on a grate in 

automatic firing equipment. 

Coal imports: Amount of foreign coal shipped to the United States, as reported in the U.S. Department of Commerce, 

Bureau of the Census, "Monthly Report IM 145." 

Coal liquefaction: Achemical process that converts coal into clean-burning liquid hydrocarbons, such as synthetic crude oil 

and methanol. 

Coal mining productivity: Coal mining productivity is calculated by dividing total coal production bythe total direct labor 

hours worked by all mine employees. 

Coal preparation: The process of sizing and cleaning coal to meet market specifications by removing impurities such as 

rock, sulfur, etc. It may include crushing, screening, or mechanical cleaning. 

Coal producing districts: A classification of coal f Ids defined in the Bituminous Coal Act of 1937. The districts were 

originally established to aid in formulating minimum prices of bituminous and subbituminous coal and lignite. Because 

much statistical information was compiled in terms of these districts, their use for statistical purposes has continued since 

the abandonment of that legislation in 1943. District 24 was added for the anthracite-producing district in Pennsylvania. 

Coal production: The sum of sales, mine consumption, issues to miners, and issues to coke, briquetting, and other 

ancillary plants at mines. Production data include quantities extracted from surface and underground mines, and normally 

exclude wastes removed at mines or associated reparation plants. 

Coal rank: The classification of coals according to their degree of progressive alteration from lignite to anthracite. In the 

United States, the standard ranks of coal include lignite, subbituminous coal, bituminous coal, and anthracite and are 

based on fixed carbon, volatile matter, heating value, and agglomerating (or caking) properties. 

Coal sampling: The collection and proper storage and handling of a relatively small quantity of coal for laboratory analysis. 

Sampling maybe done for a wide range of purposes, such as: coal resource exploration and assessment, characterization 

of their serves or production of a mine, to characterize the results of coal cleaning processes, to monitor coal shipments or 

receipts for adherence to coal quality contract specifications, or to subject a coal to specific combustion or reactivity tests 

related to the customer's intended use. During pre-development phases, such as exploration and resource assessment, 

sampling typically is from natural outcrops, test pits, old or existing mines in the region, drill cuttings, or drilled cores. 

Characterization of a mine's reserves or production may use sample collection in the mine, representative cuts from coal 

conveyors or from handling and loading equipment, or directlyfrom stockpiles or shipments (coal rail cars or barges). 

Contract specifications rely on sampling from the production flow at the mining or coal handling facility or at the loadout, or 

from the incoming shipments at the receiver's facility. In all cases, the value of a sample taken depends on its being 

representative of the coal under consideration, which in turn requires that appropriate sampling procedures be carefully 

followed. For coal resource and estimated reserve characterization, appropriate types of samples include: 

• Face channel or channel sample: a sample taken at the exposed coal in a mine by cutting away any loose or 

weathered coal then collecting on a clean surface a sample of the coal seam by chopping out a channel of uniform 

width and depth; a face channel or face sample is taken at or near the working face, the most freshly exposed coal 

where actual removal and loading of mined coal is taking place. Any partings greater than 3/8 inch and/or mineral 

concretions greater than 1/2 inch thick and 2 inches in maximum diameter are normallydiscarded from a channel 

sample so as better to represent coal that has been mined, crushed, and screened to remove at least gross noncoal materials. 

• Column sample: a channel or drill core sample taken to represent the entire geologic coalbed; it includes all 

partings and impurities that may exist in the coalbed. 

• Bench sample: a face or channel sample taken ofjust that contiguous portion of a coalbed that is considered 

practical to mine, also known as a "bench;" For example, bench samples maybe taken of minable coal where 

impure coal that makes up part of the geologic coalbed is likely to be left in the mine, or where thick partings split the 

coal into two or more distinct minable seams, or where extremely thick coalbeds cannot be recovered by normal 

mining equipment, so that the coal is mined in multiple passes, or benches, usually defined along natural bedding 

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planes. 

• Composite sample: a recombined coalbed sample produced by averaging together thickness-weighted coal 

analyses from partial samples of the coalbed, such as from one or more bench samples, from one or more mine 

exposures or outcrops where the entire bed could not be accessed in one sample, or from multiple drill cores that 

were required to retrieve all local sections of a coal seam. 

Coal stocks: Coal quantities that are held in storage for future use and disposition. Note: When coal data are collected for 

a particular reporting period (month, quarter, or year), coal stocks are commonly measured as of the last day of this period. 

Coal sulfur: Coal sulf three forms: organic, sulfate, and pyritic. Organic sulf tegral part of the coal 

matrix and cannot be removed by conventional physical separation. Sulfate sulfur is usually negligible. Pyritic sulf 

Is pyrite and marcasite; larger sizes generally can be removed by cleaning the coal. 

Coal synfuel: Coal-based solid fuel that has been processed by a coal synfuel plant; and coal-based fuels such as 

briquettes, pellets, or extrusions, which are formed from fresh or recycled coal and binding materials. 

Coal type: The classification is based on physical characteristics or microscopic constituents. Examples of coal t 

I, bright coal, cannel coal, and splint coal. The term is also used to classify coal according to heat and sulf 

t. See Coal grade. 

Coal zone: Aseries of laterally extensive and (or) lenticular coal beds and associated strata that arbitrarily can be viewed as 

a unit. Generally I beds in a coal zone are assigned to the same geologic member or formation. 

Coal-producing regions: A geographic classification of areas where coal is produced. 

• Appalachian Region: Consists of Alabama, Eastern Kentucky, Maryland, Ohio, Pennsylvania, Tennessee, Virginia, 

and West Virginia. 

• Northern Appalachian Region: Consists of Maryland, Ohio, Pennsylvania, and Northern West Virginia. 

• Central Appalachian Region: Consists of Eastern Kentucky, Virginia, Southern West Virginia, and the Tennessee 

counties of: Anderson, Campbell, Claiborne, Cumberland, Fentress, Morgan, Overton, Pickett, Putnam, Roane, and 

Scott. 

• Southern Appalachian Region: Consists of Alabama, and the Tennessee counties of: Bledsoe, Coffee, Franklin, 

Grundy, Hamilton, Marion, Rhea, Sequatchie, Van Buren, Warren, and White. 

• Interior Region (with Gulf Coast): Consists of Arkansas, Illinois, Indiana, Kansas, Louisiana, Mississippi, Missouri, 

Oklahoma, Texas, and Western Kentucky. 

• Illinois Basin: Consists of Illinois, Indiana, and Western Kentucky. 

• Western Region: Consists of Alaska, Arizona, Colorado, Montana, New Mexico, North Dakota, Utah, Washington, 

and Wyoming. 

• Powder River Basin: Consists of the Montana counties of Big Horn, Custer, Powder River, Rosebud, and Treasure 

and the Wyoming counties of Campbell, Converse, Crook, Johnson, Natrona, Niobrara, Sheridan, and Weston. 

• Uinta Basin: Consists of the Colorado counties of Delta, Garfield, Gunnison, Mesa, Moffat, Pitkin, Rio Blanco, Routt 

and the Utah counties of Carbon, Duchesne, Emery, Grand, Sanpete, Sevier, Uintah, Utah, and Wasatch. 

Coal-Producing States: The States where mined and/or purchased coal originates are defined as follows: Alabama, 

Alaska, Arizona, Arkansas, Colorado, Illinois, Indiana, Kansas, Kentucky Eastern, Kentucky Western, Louisiana, Maryland, 

Mississippi, Missouri, Montana, New Mexico, North Dakota, Ohio, Oklahoma, Pennsylvania anthracite, Pennsylvania 

bituminous, Tennessee, Texas, Utah, Virginia, Washington, West Virginia Northern, West Virginia Southern, and Wyoming. 

The following coal-producing States are split in origin of coal, as defined by 

• Kentucky, Eastern. All mines in the following counties in Eastern Kentucky. Bell, Boyd, Breathitt, Carter, Clay, 

Clinton, Elliot, Estill, Floyd, Greenup, Harlan, Jackson, Johnson, Knott, Knox, Laurel, Lawrence, Lee, Leslie, Letcher, 

Lewis, Magoffin, Martin, McCreary, Menifee, Morgan, Owsley, Perry, Pike, Powell, Pulaski, Rockcastle, Rowan, 

Wayne, Whitley, and Wolfe. 

• Kentucky, Western. All mines in the following counties in Western Kentucky. Breckinridge, Butler, Caldwell, 

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Christian, Crittenden, Daviess, Edmonson, Grayson, Hancock, Hart, Henderson, Hopkins, Logan, McLean, 

Muhlenberg, Ohio, Todd, Union, Warren, and Webster. 

• Pennsylvania Anthracite. All mines in the following counties: Carbon, Columbia, Dauphin, Lackawanna, Lebanon, 

Luzerne, Northumberland, Schuylkill, Sullivan, and Susquehanna. All anthracite mines in Bradford County. 

• Pennsylvania Bituminous. All mines located in the following counties: Allegheny, Armstrong, Beaver, Bedford, Butler, 

Cambria, Clarion, Clearfield, Elk, Fayette, Greene, Indiana, Jefferson, Lawrence, Lycoming, Somerset, Venango, 

Washington, and Westmoreland, and all bituminous mines in Bradford County. 

• West Virginia, Northern. All mines in the following counties (formerly defined as Coal-Producing Districts 1, 3, ): 

Barbour, Brooke, Braxton, Calhoun, Doddridge, Gilmer, Grant, Hancock, Harrison, Jackson, Lewis, Marion, Marshall, 

Mineral, Monongalia, Ohio, Pleasants, Preston, Randolph, Ritchie, Roane, Taylor, Tucker, Tyler, Upshur, Webster, 

Wetzel, Wirt, and Wood. 

• West Virginia, Southern. All mines in the following counties (formerly Defined as Coal-Producing Districts 7 ): 

Boone, Cabell, Clay, Fayette, Greenbrier, Kanawha, Lincoln, Logan, Mason, McDowell, Mercer, Mingo, Nicholas, 

Pocahontas, Putnam, Raleigh, Summers, Wayne, and Wyoming. 

Coalbed Methane Well Gas: Methane produced from coal seams. Coalbed methane is formed during coalification, which 

is the geologic process that transforms organic material into coal. 

Code of federal regulations: A compilation of the general and permanent rules of the executive departments and agencies 

of the Federal Government as published in the Federal Register. The code is divided into 50 titles that represent broad 

areas subject to Federal regulation. Title 18 contains the FERC regulations. 

Cofiring: The process of burning natural gas in conjunction with another fuel to reduce air pollutants. 

Cogeneration: The production of electrical energy and another form of useful energy (such as heat or steam) through the 

sequential use of energy. 

Cogeneration system: Asystem using a common energysource to produce both electricity and steam for other uses, 

resulting in increased fuel efficiency. 

Cogenerator: Agenerating facilitythat produces electricityand another form of useful thermal energy (such as heat or 

steam), used for industrial, commercial, heating, or cooling purposes. To receive status as a qualifying facility (QF) under 

the Public Utility Regulatory Policies Act (PURPA), the facility must produce electric energy and "another form of useful 

thermal energythrough the sequential use of energy' and meet certain ownership, operating, and efficiency criteria 

established by the Federal Energy Regulatory Commission (FERC).(See the Code of Federal Regulations, Title 18, Part 

292.) 

Coincidental demand: The sum of two or more demands that occur in the same time interval. 

Coincidental peak load: The sum of two or more peak loads that occur in the same time interval. 

Coke (coal): A solid carbonaceous residue derived from low-ash, low-sulf I from which the volatile 

constituents are driven off by baking in an oven at temperatures as high as 2,000 degrees Fahrenheit so that the fixed 

carbon and residual ash are fused together. Coke is used as a fuel and as a reducing agent in smelting iron ore in a blast 

f . Coke from coal is grey, hard, and porous and has a heating value of 24.8 million Btu per ton. 

Coke (petroleum): A residue high in carbon content and low in hydrogen that is the final product of thermal decomposition 

in the condensation process in cracking. This product is reported as marketable coke or catalyst coke. The conversion is 5 

barrels (of 42 U.S. gallons each) per short ton. Coke from petroleum has a heating value of 6.024 million Btu per barrel. 

Coke breeze: The term refers to the fine sizes of coke, usually less than one-half inch, that are recovered from coke plants. 

It is commonly used for sintering iron ore. 

Coke button: A button-shaped piece of coke resulting from standard laboratory tests that indicates the coking or freeswelling characteristics of a coal; expressed in numbers and compared with a standard. 

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Coke oven gas: The mixture of permanent gases produced by the carbonization of coal in a coke oven at temperatures in 

excess of 1,000 degrees Celsius. 

Coke plants: Plants where coal is carbonized for the manufacture of coke in slot or beehive ovens. 

Coking: Thermal refining processes used to produce fuel gas, gasoline blendstocks, distillates, and petroleum coke from 

the heavier products of atmospheric and vacuum distillation. Includes: 

• Delayed Coking. A process bywhich heavier crude oil f tions can be thermally decomposed under conditions of 

elevated temperatures and pressure to produce a mixture of lighter oils and petroleum coke. The light oils can be 

processed further in other refinery units to meet product specifications. The coke can be used either as a fuel or in 

other applications such as the manufacturing of steel or aluminum. 

• Flexicoking. Athermal cracking process which converts heavy hydrocarbons such as crude oil, tar sands bitumen, 

and distillation residues into light hydrocarbons. Feedstocks can be any pumpable hydrocarbons including those 

containing high concentrations of sulfur and metals. 

• Fluid Coking. Athermal cracking process utilizing the fluidized-solids technique to remove carbon (coke) for 

continuous conversion of heavy, low-grade oils into lighter products. 

Coking coal: Bituminous coal suitable for making coke. See coke (coal). 

Cold-deck imputation: A statistical procedure that replaces a missing value of an item with a constant value from an 

external source such as a value from a previous survey. See Imputation. 

Combined cycle: An electric generating technology in which electricity is produced from otherwise lost waste heat exiting 

from one or more gas (combustion) turbines. The eating heat is routed to a conventional boiler or to a heat recovery steam 

generator for utilization by a steam turbine in the production of electricity. This process increases the efficiency of the electric 

generating unit. 

Combined cycle unit: An electric generating unit that consists of one or more combustion turbines and one or more boilers 

with a portion of the required energy input to the boiler(s) provided by the exhaust gas of the combustion turbine(s). 

Combined heat and power (CHP) plant: A plant designed to produce both heat and electricity from a single heat source. 

Note: This term is being used in place of the term "cogenerator" that was used by EIA in the past. CHP better describes the 

facilities because some of the plants included do not produce heat and power in a sequential fashion and, as a result, do 

not meet the legal definition of cogeneration specified in the Public Utility Regulatory Policies Act (PURPA). 

Combined household energy expenditures: The total amount of funds spent for energy cons urned in, or delivered to, a 

housing unit during a given period of time and for fuel used to operate the motor vehicles that are owned or used on a 

regular basis bythe household. The total dollar amount for energy consumed in a housing unit includes state and local 

taxes but excludes merchandise repairs or special service charges. Electricity, and natural gas expenditures are for the 

amount of those energysources consumed. Fuel oil, kerosene, and LPG expenditures are for the amount of fuel 

purchased, which may differ from the amount of fuel consumed. The total dollar amount of fuel spent for vehicles is the 

product of fuel consumption and price. 

Combined hydroelectric plant: A hydroelectric plant that uses both pumped water and natural streamflow for the 

production of power. 

Combined pumped-storage plant: A pumped-storage hydroelectric power plant that uses both pumped water and natural 

stream flow to produce electricity. 

Combustion: Chemical oxidation accompanied bythe generation of light and heat. 

Combustion chamber: An enclosed vessel in which chemical oxidation of fuel occurs. 

Commercial building: A building with more than 50 percent of its floor space used for commercial activities. Commercial 

buildings include, but are not limited to, stores, offices, schools, churches, gymnasiums, libraries, museums, hospitals, 

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clinics, warehouses, and jails. Government buildings are included except for buildings on military bases or reservations. 

Commercial f lity: An economic unit that is owned or operated by one person or organization and that occupies two or 

more commercial buildings at a single location. A university and a large hospital com plex are examples of a commercial 

multi-building facility. 

Commercial operation (nuclear): The phase of reactor operation that begins when power ascension ends and the 

operating utility form ally declares the nuclear power plant to be available for the regular production of electricity. This 

declaration is usually related to the satisfactory completion of qualification tests on critical components of the unit. 

Commercial sector: An energy-consuming sector that consists of service-providing facilities and equipment of 

businesses; Federal, State, and local governments; and other private and public organizations, such as religious, social, or 

fraternal groups. The commercial sector includes institutional living quarters. It also includes sewage treatment facilities. 

Common uses of energy associated with this sector include space heating, water heating, air conditioning, lighting, 

refrigeration, cooking, and running a wide variety of other equipment. Note: This sector includes generators that produce 

electricity and/or useful thermal output primarily to support the activities of the above-mentioned commercial 

establishments. 

Commingling: The mixing of one utility's generated supply of electric energywith another utility's generated supplywithin a 

transmission system. 

Commissioned agent: An agent who wholesales or retails a refined petroleum product under a commission arrangement. 

The agent does not take title to the product or establish the selling price, but receives a percentage of fixed fee for serving 

as an agent. 

Common equity (book value): The retained earnings and common stock earnings plus the balances in common equity 

reserves and all other common stock accounts. This also includes the capital surplus, the paid-in surplus, the premium on 

common stocks, except those balances specifically related to preferred or preference stocks; less any common stocks held 

in the treasury. 

Compact fluorescent bulbs: These are also known as "screw-in fluorescent replacements for incandescent" or "screwins." Compactfluorescent bulbs combine the efficiency of fluorescent lighting with the convenience of a standard 

incandescent bulb. There are many styles of com pact fluorescent, including exit light f tures and floodlights (lamps 

containing reflectors). Many screw into a standard light socket, and most produce a similar color of light as a standard 

incandescent bulb. Compact fluorescent bulbs come with ballasts that are electronic (lightweight, instant, no-flicker starting, 

and 10to 15% more efficient) or magnetic (much heavier and slower starting).Other ty t fluorescent bulbs 

include adaptive circulation and PL and SL lamps and ballasts. Compactfluorescent bulbs are designed for residential 

uses; they are also used in table lamps, wall sconces, and hall and ceiling fixtures of hotels, motels, hospitals, and other 

types of commercial buildings with residential-t lications. 

Company: See Firm. 

Company automotive (retail) outlet: Any retail outlet selling motor fuel under the brand name of a company reporting in the 

EIA Financial Reporting System. 

Company outlet: See Company-operated automotive outlet. 

Company-lessee automotive outlet: One of three types of company automotive (retail) outlets. This type of outlet is 

operated by an independent marketer who leases the station and land and has use of tanks, pumps, signs, etc. A lessee 

dealer typically has a supplyagreement with a refiner or a distributor and purchases products at dealer tank wagon prices. 

The term includes outlets operated by commissioned agents and is limited to those dealers who are supplied directly by a 

refiner or any aff liate or subsidiary company of a refiner. 

Company-open automotive outlet: One of three types of company automotive (retail) outlets. This ty f outlet is operated 

by an independent marketer who owns or leases (f third party that is not a refiner) the station or land of a retail outlet 

and has use of tanks, pumps, signs, etc. An open dealer typically has a supply agreement with a refiner or a distributor and 

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purchases products based on either rack or dealer tank wagon prices. 

Company-operated automotive outlet: One of three types of com pany automotive (retail) outlets. This type of outlet is 

operated by salaried or commissioned personnel paid bythe reporting company. 

Company-operated outlet: SeeCompany-operated retail outlet. 

Company-operated retail outlet: Any retail outlet (i.e., service station) which sells motor vehicle fuels and is under the 

direct control of a firm that sets the retail product price and directly collects all or part of the retail margin. The category 

includes retail outlets operated by (1) salaried employees of the firm and/or its subsidiaries and affiliates, (2) licensed or 

commissioned agents, and/or (3) personnel services contracted by the firm. 

Competitive transition charge: A non-bypassable charge levied on each customer of the distribution utility, including those 

who are served under contracts with nonutility suppliers, for recovery of the utilitys stranded costs that develop because of 

corn petition. 

Completion (oil/gas production): The term refers to the installation of permanent equipment for the production of oil or gas. 

If a well is equipped to produce only oil or gas from one zone or reservoir, the definition of a "well" (classified as an oil well 

or gas well) and the definition of a "completion" are identical. However, if a well is equipped to produce oil and/or gas 

separately from more than one reservoir, a "well" is not synonymous with a "completion." (SeeWell.) 

Completion date (oil/gas production): The date on which the installation of permanent equipment has been completed as 

reported to the appropriate regulatory agency. The date of completion of a dry hole is the date of abandonment as reported 

to the appropriate agency. The date of completion of a service well is the date on which the well is equipped to perform the 

service for which it was intended. 

Compliance coal: Acoal or a blend of coals that meets sulf tandards for air quality without the need for 

flue gas desulf tion. 

Compressed natural gas (CNG): Natural gascompressed to a pressure at or above 200-248 bar (i.e., 2900-3600 pounds 

per square inch) and stored in high-pressure containers. It is used as a fuel for natural gas-powered vehicles. 

Compressor station: Any com bination of facilities that supply the energy to move gas in transmission or distribution lines 

or into storage by increasing the pressure. 

Concentrating solar power or solar thermal power system: Asolar energy conversion system characterized by the optical 

concentration of solar rays through an arrangement of mirrors to generate a high temperature working fluid. Also seeSolar 

trough, Solar power tower, orSolar dish. Concentrating solar power (but not Solar thermal power) may also refer to a 

system that focuses solar rays on aphotovoltaic cell to increase conversion efficiency. 

Concentrator: A reflective or refractive device that focuses incident insolation onto an area smaller than the reflective or 

refractive surface, resulting in increased insolation at the point of focus. 

Concession: The operating right to explore for and develop petroleum fields in consideration for a share of production in 

kind (equity oil). 

Concessionary purchases: The quantity of crude oil exported during a reporting period, which was acquired from the 

producing government under terms that arise from the firm's participation in a concession. It includes preferential crude 

where the reporting firm's access to such crude is derived from a former concessionary relationship. 

Condensate (lease condensate): A natural gas liquid recovered from associated and non associated gas wells from lease 

separators or field facilities, reported in barrels of 42 U.S. gallons at atmospheric pressure and 60 degrees Fahrenheit. 

Condenser cooling water: Asource of water external to a boiler's feed system is passed through the steam leaving the 

turbine in order to cool and condense the steam. This reduces the steam's exit pressure and recaptures its heat, which is 

then used to preheat fluid entering the boiler, thereby increasing the plant's thermodynamic eff 

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Conditionally effective rates: An electric rate schedule that has been put into effect by the FERC subject to refund pending 

final disposition or refiling. 

Conductor: Metal wires, cables, and bus-bar used for carrying electric current. Conductors maybe solid or stranded, that 

is,built up bya assemblyof smaller solid conductors. 

Conference of the parties (COP): The collection of nations that have ratified the Framework Convention on Climate 

Change(FCCC). The primary role of the COP is to keep implementation of the FCCC under review and make the decisions 

necessary for its effective implementation. Also see Framework Convention on Climate Change (FCCC). 

Configuration maps: Geographic information containing transmission line, substation, and terminal information. Its hows 

the normal operating voltages and includes information about other operational and political boundaries. 

Congestion: A condition that occurs when insufficient transfer capacity is available to implement all of the preferred 

schedules for electricity transmission simultaneously. 

Connected load: The sum of the continuous ratings or the capacities for a system, part of a system, or a customer's electric 

power consuming apparatus. 

Connection: The physical connection (e.g., transmission lines, transformers, switch gear, etc.) between two electric 

systems permitting the transfer of electric energy in one or both directions. 

Conservation: A reduction in energy consumption that corresponds with a reduction in service demand. Service demand 

can include buildings-sector end uses such as lighting, refrigeration, and heating; industrial processes; or vehicle 

transportation. Unlike energy efficiency, which is typically a technological measure, conservation is better associated with 

behavior. Examples of conservation include adjusting the thermostat to reduce the output of a heating unit, using occupancy 

sensors that turn off lights or appliances, and car-pooling. 

Conservation feature: Afeature in the building designed to reduce the usage of energy. 

Conservation program: A program in which a utility com pany furnis hes home weatherization services free or at reduced 

cost or provides free or low cost devices for saving energy, such as energy efft light bulbs, flow restrictors, weather 

stripping, and water heater insulation. 

Consolidated entity: See Firm. 

Consolidated Metropolitan Statistical Area (CMSA): An area that meets the requirements of a metropolitan statistical area, 

has a population of one million or more, and consists of two or more corn ponent parts that are recognized as primary 

metropolitan statistical areas. 

Construction: An energy-consuming subsector of the industrial sector that consists of all facilities and equipment used to 

perform land preparation and construct, renovate, alter, install, maintain, or repair major infrastructure or individual systems 

therein. Infrastructure includes buildings; industrial plants; and other major structures, such as tanks, towers, monuments, 

roadways, tunnels, bridges, dams, pipelines, and transmission lines. 

Construction costs (of the electric power industry): All direct and indirect costs incurred in acquiring and constructing 

electric utility plant and equipment and proportionate shares of common utility plants. Included are the cost of land and 

improvements, nuclear fuel and spare parts, allowance for funds used during construction, and general overheads 

capitalized, less the cost of acquiring plant and equipment previously operated in utilityservice. 

Construction expenditures (of the electric power industry): The gross expenditures for construction costs (including the 

cost of replacing worn out plants), and electric construction costs, and land held for future use. 

Construction pipeline (of a nuclear reactor): The various stages involved in the acquisition of a nuclear reactor bya utility. 

The events that define these stages are the ordering of a reactor, the licensing process, and the physical construction of the 

nuclear generating unit. A reactor is said to be "in the pipeline" when the reactor is ordered and "out of the pipeline" when it 

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completes low power testing and begins operation toward full power. 

Construction work in progress (C IP): The balance shown on a utility's balance sheet for construction work not yet 

completed butin process. This balance line item mayor may not be included in the rate base. 

Constructive surplus or deficit: The amounts representing the exchange of services, supplies, etc., between the utility 

department and the municipality and its other departments without charge or at a reduced charge. Charges to this account 

include utility and other services, supplies, etc., furnished bythe utility department to the municipality or its other 

departments without charge, or the amount of the reduction, if furnished at a reduced charge. Credits to the account consist 

of services, supplies, office space, etc., furnished bythe municipalityto the utilitydepartment without charge on the amount 

of the reduction, if furnished at a reduced charge. 

Consumer (energy): Any individually metered dwelling, building, establishment, or location using natural gas, synthetic 

natural gas, and/or mixtures of natural and supplemental gas for feedstock or as fuel for any purpose other than in oil or 

gas lease operations; natural gas treating or processing plants; or pipeline, distribution, or storage compressors. 

Consumer charge: An amount charged periodicallyto a consumer for such utility costs as billing and meter reading, 

without regard to demand or energy consumption. 

Consumer Price Index (CPI): These prices are collected in 85 urban areas selected to represent all urban consumers 

about 80 percent of the total U.S. population. The service stations are selected initially and on a replacement basis, in such 

a way that they represent the purchasing habits of the CPI population. Service stations in the current sample include those 

providing all types of service (i.e., full, mini, and self service). 

Consumption: SeeEnergy cons urnption. 

Consumption per square foot: The aggregate ratio of total consumption for a particular set of buildings to the total 

floors pace of those buildings. 

Continuous delivery energy sources: Those energy sources provided continuously to a building. 

Continuous mining: Aform of room pillar mining in which a continuous mining machine extracts and removes coal from the 

working face in one operation; no blasting is required. 

Contract price: The delivery price determined when a contract is signed. It can be a fixed price or a base price escalated 

according to a given formula. 

Contract receipts: Purchases based on a negotiated agreement that generally covers a period of 1 or more years. 

Contracted gas: Any gas for which Interstate Pipeline has a contract to purchase from anydomestic or foreign source that 

cannot be identified to a specific field or group. This includes tailgate plant purchases, single meter point purchases, 

pipeline purchases, natural gas imports, SNG purchases, and LNG purchases. 

Contribution to net income: The FRS (Financial Reporting System survey) segment equivalent to net income. However, 

some consolidated items of revenue and expense are not allocated to the segments, and therefore they are not equivalent 

in a strict sense. The largest item not allocated to the segments is interest expense since this is regarded as a corporate 

level item for FRS purposes. 

Control: Including the terms "controlling," "controlled by," and "under common control with," means the possession, direct 

or indirect, of the power to direct or cause the direction of the management and policies of a person, whether through the 

ownership of voting shares, by contract, or otherwise. 

Control total: The number of elements in the population or a subset of the population. The sample weights for the 

observed elements in a survey are adjusted so that they add up to the control total. The value of a control total is obtained 

from an outside source. The control totals are given bythe number of households in one of the 12 cells by categorizing 

households bythe four Census regions and bythree categories of metropolitan status (Metropolitan Statistical Area central 

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city, Metropolitan Statistical Area outside central city, and non Metropolitan Statistical Area). The control totals are obtained 

from the Current Population Survey. 

Conventional blendstock for oxygenate blending (CBOB): Motor gasoline blending corn ponents intended for blending with 

oxygenates to produce finished conventional motor gasoline. 

Conventional gasoline: Finished motor gasoline not included in the oxygenated or reformulated gasoline categories. Note: 

This category excludes reformulated gasoline blendstock for oxygenate blending (RBOB) as well as other blendstock. 

Conventional hydroelectric plant: A plant in which all of the power is produced from natural streamflow as regulated by 

available storage. 

Conventional mill (uranium): Afacility engineered and built principallyfor processing of uraniferous ore materials mined 

from the earth and the recovery, by chemical treatment in the mill's circuits, of uranium and/or other valued coproduct 

components from the processed one. 

Conventional mining: The oldest form of room pillar mining, which consists of a series of operations that involve cutting the 

coal bed, so it breaks easilywhen blasted with explosives or high pressure air, and then loading the broken coal. 

Conventional oil and natural gas production: Crude oil and natural gas that is produced by a well drilled into a geologic 

formation in which the reservoir and fluid characteristics permit the oil and natural gas to readilyflow to the wellbore. 

Conventionally fueled vehicle: Avehicle that runs on petroleum-based fuels such as motor gasoline or diesel f I. 

Conversion company: An organization that performs vehicle conversions on a commercial basis. 

Conversion factor: Afactor for converting data between one unit of measurement and another (such as between short tons 

and British thermal units, or between barrels and gallons). (Seehttp://www.eia.doe.gov/erneu/mer/append_a.html and 

http://www.eia.doe.gov/emeu/mer/append_b.html for further information on conversion factors.) SeeBtu Conversion Factor 

and Thermal Conversion Factor. 

Converted (alternative-fuel) vehicle: Avehicle originally designed to operate on gasoline/diesel that was modified or 

altered to run on an alternative fuel after its initial deliveryto an end-user. 

Cooling: Conditioning of room air for human comfort bya refrigeration unit (such as an air conditioner or heat pump) or by 

circulating chilled water through a central cooling or district cooling system. Use of fans or blowers by themselves, without 

chilled air or water, is not included in this definition of cooling. 

Cooling degree-days: A measure of how warm a location is over a period of time relative to a base temperature, most 

commonlyspecified as 65 degrees Fahrenheit. The measure is computed for each day by subtracting the base 

temperature (65 degrees) f the days high and low temperatures, with negative values set equal to zero. 

Each days cooling degree-days are summed to create a cooling degree-day measure for a specified reference period. 

Cooling degree-days are used in energy analysis as an indicator of air conditioning energy requirements or use. 

Cooling pond: A natural or manmade body of water that is used for dissipating waste heat f !ants. 

Cooling system: An equipment system that provides water to the condensers and includes water intakes and outlets; 

cooling towers; and ponds, pumps, and pipes. 

Cooperative electric utility: An electric utility legally established to be owned by and operated for the benefit of those using 

its service. The utility com panywill generate, transmit, and/or distribute supplies of electric energy to a specified area not 

being serviced by another utility. Such ventures are generally exem pt f I income tax laws. Most electric 

cooperatives have been initiallyfinanced bythe Rural Utilities Service (prior Rural Electrification Administration), U.S. 

Department of Agriculture. 

Coordination service: The sale, exchange, or transmission of electricity between two or more electric utilities that typically 

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have sufficient generation and transmission capacityto supplytheir load requirements under normal conditions. 

Coordination service pricing: The typical price components of a bulk power coordination sale are an energy charge, a 

capacity, or reservation charge, and an adder. The price for a particular sale may embody some or all of these components. 

The energy charge is made on a per-kilowatt basis and is intended to recover the seller's system incremental variable 

costs of making a sale. Because the nonfuel expenses are usually hard to quantify, and small relative to fuel expense, 

energy charges quoted are usually based on fuel cost. Acapacity charge is set at a certain level per kilowatt and is normally 

paid whether or not energy is taken by the buyer. An adder is added to that energy charge to recover the hard quantify 

nonfuel variable costs. There are three types of adders percentage, f , and split savings. A percentage adder increases 

the energy charge by a certain percentage. A fixed adder adds a fixed amount per kilowatt hour to the energy charge. Split 

savings adders are used only in economy energytransactions. Theysplit production costs savings between the seller and 

the buyer by adding one half of the savings to the energy cost. 

Cord of wood: A cord of wood measures 4 feet by 4feet by 8 feet, or 128 cubic feet. 

Correlation (statistical term): In its most general sense, correlation denotes the interdependence between quantitative or 

qualitative data. It would include the association of dichotomized attributes and the contingency of multiple classified 

attributes. The concept is quite general and may be extended to more than two variates .The word is most frequently used in 

a somewhat narrower sense to denote the relationship between measurable variates or ranks. 

Cost model f zed algorithm that uses the uranium endowment estimated for a 

given geological area and selected industr lop random variables that describe the undiscovered 

resources ultimately expected to be discovered in that area at chosen forward cost categories. 

Cost of capital: The rate of return a utility must offer to obtain additional f . The cost of capital varies with the leverage 

ratio, the effective income tax rate, conditions in the bond and stock markets, growth rate of the utility, its dividend strategy, 

stability of net income, the amount of new capital required, and other factors dealing with business and financial risks. It is a 

composite of the cost for debt interest, preferred stock dividends, and common stockholders' earnings that provide the 

facilities used in supplying utility service. 

Cost of debt: The interest rate paid on new increments of debt capital multiplied by 1 minus the tax rate. 

Cost of preferred stock: The preferred stock dividends divided by the net price of the preferred stock. 

Cost of retained earnings: The residual of an entity's earnings over expenditures, including taxes and dividends, that are 

reinvested in its business. The cost of these funds is always lower than the cost of new equity capital, due to taxes and 

transactions costs. Therefore, the cost of retained earnings is the yield that retained earnings accrue upon reinvestment. 

Cost of service: Aratemaking concept used for the design and development of rate schedules to ensure that the filed rate 

schedules recover only the cost of providing the electric service at issue. This concept attempts to correlate the utility's costs 

and revenue with the service provided to each of the various customer classes. 

Cost, insurance, freight (CIF): Atype of sale in which the buyer of the product agrees to pay a unit price that includes the 

f.o.b. value of the product at the point of origin plus all costs of insurance and transportation. This ty f transaction differs 

from a "delivered" purchase in that the buyer accepts the quantity as determined at the loading port (as certified bythe Bill of 

Lading and Quality Report) rather than pay on the basis of the quantity and quality ascertained at the unloading port. It is 

similar to the terms of an f.o.b. sale except that the seller, as a service for which he is compensated, arranges for 

transportation and insurance. 

Cost-based rates (electric): Aratemaking concept used for the design and development of rate schedules to ensure that 

the filed rate schedules recover only the cost of providing the service. FERC definition 

Cost-of-service regulation: A traditional electric utility regulation under which a utility is allowed to set rates based on the 

cost of providing service to customers and the right to earn a limited profit. 

Costs (imports of natural gas): All expenses incurred by an importer up to the U.S. point of delivery for the reported quantity 

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{of natural gas) imported. 

CPI: Consumer Price Index 

Criteria pollutant: A pollutant determined to behazardous to human health and regulated under EPA's National Ambient Air 

Quality Standards. The 1970 amendments to the Clean Air Act require EPAto describe the health and welfare impacts of a 

pollutant as the "criteria" for inclusion in the regulatory regime. 

Crop residue: Organic residue remaining after the harvesting and processing of a crop. 

Crude oil: Amixture of hydrocarbons that exists in liquid phase in natural underground reservoirs and remains liquid at 

atmospheric pressure after passing through surface separating facilities. Depending upon the characteristics of the crude 

stream, it may also include 1. Small amounts of hydrocarbons that exist in gaseous phase in natural underground 

reservoirs but are liquid at atmospheric pressure after being recovered from oil well (casing head) gas in lease separators 

and are subsequently com ingled with the crude stream without being separately measured. Lease condensate recovered 

as a liquid from natural gas wells in lease or field separation facilities and later mixed into the crude stream is also 

included; 2. Small amounts of nonhydrocarbons produced with the oil, such as sulfur and various metals; 3. Drip gases, 

and liquid hydrocarbons produced from tar sands, oil sands, gilsonite, and oil shale. 

Liquids produced at natural gas processing plants are excluded. Crude oil is refined to produce a wide array of petroleum 

products, including heating oils; gasoline, diesel and jet fuels; lubricants; asphalt; ethane, propane, and butane; and many 

other products used for their energy or chemical content. 

Crude oil acquisitions (unfinished oil acquisitions): The volume of crude oil either: 

• acquired bythe respondent for processing for his own account in accordance with accounting procedures generally 

accepted and consistently and historically applied bythe refiner concerned, or 

• in the case of a processing agreement, delivered to another refinery for processing for the respondent's own 

account. 

Crude oil that has not been added by a refiner to inventory and that is thereafter sold or otherwise disposed of without 

processing for the account of that refiner shall be deducted from its crude oil purchases at the time when the related 

cost is deducted from refinery inventory in accordance with accounting procedures generally applied by the refiner 

concerned. Crude oil processed by the respondent for the account of another is not a crude oil acquisition. 

Crude oil f.o.b. price: The crude oil price actually charged at the oil producing countrys port of loading. Includes deductions 

for any rebates and discounts or additions of premiums, where applicable. It is the actual price paid with no adjustment for 

credit terms. 

Crude oil input: The total crude oil put into processing units at refineries. 

Crude oil landed cost: The price of crude oil at the port of discharge, including charges associated with purchasing, 

transporting, and insuring a cargo from the purchase point to the port of discharge. The cost does not include charges 

incurred at the discharge port (e.g., import tariffs or fees, wharfage charges, and demurrage). 

Crude oil less lease condensate: Amixture of hydrocarbons that exists in liquid phase in natural underground reservoirs 

and remains liquid at atmospheric pressure after passing through surface separating facilities. Such hydrocarbons as 

lease condensate and natural gasoline recovered as liquids from natural gas wells in lease or field separation facilities 

and later mixed into the crude stream are excluded. Depending upon the characteristics of the crude stream, crude oil may 

also include: 1. Small amounts of hydrocarbons that exist in gaseous phase in natural underground reservoirs but are 

liquid at atmospheric pressure after being recovered from oil well (casinghead) gas in lease separators and are 

subsequently com ingled with the crude stream without being separately measured; 2. Small amounts of on hydrocarbons 

produced with the oil, such as sulfur and various metals. 

Crude oil losses: Represents the volume of crude oil reported by petroleum refineries as being lost in their operations. 

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These losses are due to spills, contamination, fires, etc., as opposed to refining processing losses. 

Crude oil production: The volume of crude oil produced from oil reservoirs during given periods of time. The amount of 

such production for a given period is measured as volumes delivered from lease storage tanks (i.e., the point of custody 

transfer) to pipelines, trucks, or other media for transport to refineries or terminals with adjustments for (1) net differences 

between opening and closing lease inventories, and (2) basic sediment and water (BSw). 

Crude oil qualities: Refers to two properties of crude oil, the sulf I gravity, which affect processing 

complexity and product characteristics. 

Crude oil refinery input: The total crude oil put into processing units at refineries. 

Crude oil stocks: Stocks of crude oil and lease condensate held at refineries, in pipelines, at pipeline terminals, and on 

leases. 

Crude oil used directly: Crude oil consumed as fuel by crude oil pipelines and on crude oil leases. 

Crude oil, refinery receipts: Receipts of domestic and foreign crude oil at a refinery. Includes all crude oil in transit except 

crude oil in transit by pipeline. Foreign crude oil is reported as a receipt only after entry through customs. Crude oil of foreign 

origin held in bonded storage is excluded. 

Crystalline fully refined wax: Alight colored paraffin wax having the following characteristics: 

• viscosity at 210 degrees Fahrenheit (D88)-59.9 SUS (10.18 centistokes) maximum; 

• oil content (D721)-0.5 percent maximum; 

• other +20 color, Saybolt minimum. 

Crystalline other wax: A paraffin wax having the following characteristics: 

• viscosity at 210 deg. F(D88)-59.9 SUS (10.18centistokes) maximum; 

• oil content (D721)-0.51 percent minimum to 15 percent maximum. 

Cubic foot (cf), natural gas: The amount of natural gas contained at standard temperature and pressure (60 degrees 

Fahrenheit and 14.73 pounds standard per square inch) in a cube whose edges are one foot long. 

Cull wood: Wood logs, chips, or wood products that are burned. 

Culm: Waste from Pennsylvania anthracite preparation plants, consisting of coarse rock fragments containing as much as 

30 percent small sized coal; sometimes defined as including veryfine coal particles called silt. Its heat value ranges from 8 

to 17 million Btu per short ton. 

Cultivar: A horticulturally or agriculturally derived variety of a plant. 

Cumulative depletion: The sum in tons of coal extracted and lost in mining as of a stated date for a specified area or a 

specified coal bed. 

Current (electric): Allow of electrons in an electrical conductor. The strength or rate of movement of the electricity is 

measured in amperes. 

Current assets: Cash and other assets that are expected to be turned into cash, sold, or exchanged within the normal 

operating cycle of the utility, usually one year. Current assets include cash, marketable securities, receivables, inventory, 

and current prepayments. 

Current liabilities: A debt or other obligation that must be discharged within one year or the normal operating cycle of the 

utility by expending a current asset or the incurrence of another short-term obligation. Current liabilities include accounts 

payable, short-term notes payable, and accrued expenses payable such as taxes payable and salaries payable. 

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Current ratio: The ratio of current assets divided by current liabilities that shows the abilityof a utilityto pay its current 

obligations from its current assets. A m easure of liquidity, the higher the ratio, the more assurance that current liabilities 

can be paid. 

Customer choice: The right of customers to purchase energy from a supplier other than their traditional supplier or from 

more than one seller in the retail market. 

Customs district (coal): Customs districts, as defined bythe Bureau of the Census, U.S. Department of Commerce, " 

Monthly Report EM 545, " are as follows: 

• Eastern: Bridgeport, CT, Washington, DC, Boston, MA, Baltimore, MD, Portland, ME, Buffalo, NY, New York City, NY, 

Ogdensburg, NY, Philadelphia, PA, Providence, RI, Norfolk, VA, St. Albans, VT. 

• Southern: Mobile, AL, Savannah, GA, Miami, FL, Tampa, FL, New Orleans, LAImington, NC, San Juan, PR, 

Charleston, SC, Dallas-Fort Worth, TX El Paso, TX, Houston-Galveston, TX, Laredo, TX Islands. 

• Western: Anchorage, AK, Nogales, AZ, Los Angeles, CA, San Diego, CA, San Francisco, CA, Honolulu, HI, Great 

Falls, MT, Portland, OR, Seattle, WA 

• Northern: Chicago, IL, Detroit, MI, Duluth, MN, Minneapolis, MN, St. Louis, MO, Pembina, ND, Cleveland, OH, 

Milwaukee, WI. 

Customs import value (C.I.V.): The price for a one-time open market transaction for near-term delivery of a specific quantity 

of product at a specific location where the commodity is purchased LDQUO; on the spot RDQUO; at current market rates. 

See alsospotmarket terms associated with specific energy types. 

Cut-off grade (uranium): The lowest grade, in percent U308, of uranium ore at a minimum specified thickness that can be 

mined at a specified cost. 

C IP: Construction WorkInProgress 

Cycle: The time period running from the startup of one reactor cycle to the startup of the following cycle. 

C le/reactor history: Agroup of assemblies that have been irradiated in the same cycles in an individual reactor and are 

said to have the same cycle/reactor history. 

C ling (natural gas): The practice of producing natural gas for the extraction of natural gas liquids, returning the dry 

residue to the producing reservoir to maintain reservoir pressure and increase the ultimate recovery of natural gas liquids. 

The reinjected gas is produced for disposition after cycling operations are completed. 

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Dam: A physical barrier constructed across a river or waterway to control the flow of or raise the level of water. The purpose 

of construction maybe for flood control, irrigation needs, hydroelectric power production, and/or recreation usage. 

Day-ahead and hour-ahead markets: Forward markets where electricity quantities and market clearing prices are 

calculated individuallyfor each hour of the day on the basis of participant bids for energy sales and purchases. 

Day-ahead schedule: Aschedule prepared bya scheduling coordinator or the independent system operator before the 

beginning of a trading day. This schedule indicates the levels of generation and demand scheduled for each settlement 

period that trading day. 

Daylighting controls: Asystem of sensors that assesses the amount of daylight and controls lighting or shading devices to 

maintain a specified lighting level. The sensors are sometimes referred to as "photocells." 

DC: Direct Current 

Deadweight tons: The lifting capacity of a ship expressed in long tons (2,240 lbs.), including cargo, commodities, and 

crew. 

Dealer tank wagon (DTW) sales: Wholesale sales of gasoline priced on a delivered basis to a retail outlet. 

Decatherm: Ten therms or 1,000,000 Btu. 

Decommissioning: Retirement of a nuclear facility, including decontamination and/or dismantlement. 

Decontamination: Removal of unwanted radioactive or hazardous contamination bya chemical or mechanical process. 

Dedicated reserves: The volume of recoverable, salable gas reserves committed to, controlled by, or possessed by the 

reporting pipeline company and used for acts and services for which both the seller and the company have received 

certificate authorization from the Federal Energy Regulatory Commission (FERC). Reserves include both company-owned 

reserves (including owned gas in underground storage),reserves under contract from independent producers, and shortterm and emergency supplies from the intrastate market. Gas volumes under contract from other interstate pipelines are 

not included as reserves, but may constitute part or all of a companys gas supply. 

Dedicated vehicle: Avehicle that operates only on an alternative fuel, as when a vehicle is configured to operate on 

compressed natural gas. Note: Avehicle powered by an electric motor is not to be treated as dedicated. 

Deepest total depth: The deepest total depth of a given well is the distance from a surface reference point (usually the Kelly 

bushing) to the point of deepest penetration measured along the well bore. If a well is drilled from a platform or barge over 

water, the depth of the water is included in the total length of the well bore. 

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Deferred cost: An expenditure not recognized as a cost of operation of the period in which incurred, but carried forward to 

be written off in future periods. 

Deferred fuel costs: An expenditure for fuel that is not recognized for bookkeeping practices as a cost in the operating 

period incurred, but carried forward to be written off in future periods. 

Deferred income tax (liability): A liability in the balance sheet representing the additional Federal income taxes that would 

have been due if a utility had not been allowed to compute tax expenses differentlyfor income tax reporting purposes than 

for ratemaking purposes. 

Deforestation: The net removal of trees from forested land. 

Degasification system: The methods employed for removing methane from a coal seam that could not otherwise be 

removed by standard ventilation fans and thus would pose a substantial hazard to coal miners. These systems maybe 

used prior to mining or during mining activities. 

Degradable organic carbon: The portion of organic carbon present in such solid waste as paper, food waste, and yard 

waste that is susceptible to biochemical decomposition. 

Delayed coking: A process bywhich heavier crude oil fractions can be thermally decomposed under conditions of elevated 

temperatures and pressure to produce a mixture of lighter oils and petroleum coke. The light oils can be processed further 

in other refinery units to meet product specifications. The coke can be used either as a fuel or in other applications such as 

the manufacturing of steel or aluminum. 

Deliverability: Represents the number of future years during which a pipeline company can meet its annual requirements 

for its presently certificated delivery capacity from presently comm itted sources of supply. The availability of gas from these 

sources of supply shall be governed by the physical capabilities of these sources to deliver gas by the terms of existing 

gas-purchase contracts, and by limitations imposed by State or Federal regulatory agencies. 

Delivered (gas): The physical transfer of natural, synthetic, and/or supplemental gas from facilities operated bythe 

responding companyto facilities operated by others or to consumers. 

Delivered cost: The cost of fuel, including the invoice price of fuel, transportation charges, taxes, commissions, insurance, 

and expenses associated with leased or owned equipment used to transport the fuel. 

Delivered energy: The amount of energy delivered to the site (building); no adjustment is made for the fuels consumed to 

produce electricity or district sources. This is also referred to as net energy. 

Deliveries (electric): Energy generated by one system and delivered to another system through one or more transmission 

lines. 

Demand: SeeEnergy demand. 

Demand bid: A bid into the power exchange indicating a quantity of energy or an ancillaryservice that an eligible customer 

is willing to purchase and, if relevant, the maximum price that the customer is willing to pay. 

Demand charge: That portion of the consumer's bill for electric service based on the consumer's maximum electric 

capacity usage and calculated based on the billing demand charges under the applicable rate schedule. 

Demand charge credit: Compensation received by the buyer when the delivery terms of the contract cannot be met by the 

seller. 

Demand indicator: A measure of the number of energy-consuming units, or the amount of service or output, for which 

energy inputs are required. 

Demand interval: The time period during which flow of electricity is measured (usually in 15-, 30-, or 60-minute 

increments.) 

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Demand-metered: Having a meter to measure peak demand (in addition to total consumption) during a billing period. 

Demand is not usually metered for other energy sources. 

Demand-side management (DSM): A utility action that reduces or curtails end-use equipment or processes. DSM is often 

used in order to reduce customer load during peak demand and/or in times of supply constraint. DSM includes programs 

that are focused, deep, and immediate such as the brief curtailment of energy-intensive processes used bya utility's most 

demanding industrial customers, and programs that are broad, shallow, and less immediate such as the promotion of 

energy-efficient equipment in residential and commercial sectors. 

Demand-side management costs: The costs incurred by the utility to achieve the capacity and energy savings from the 

Demand-Side Management Program. Costs incurred by customers or third parties are to be excluded. The costs are to be 

reported in thousands of dollars (nominal) in the year in which they are incurred, regardless of when the savings occur. The 

utility costs are all the annual expenses (labor, administrative, equipment, incentives, marketing, monitoring and evaluation, 

and other incurred by the utilityfor operation of the DSM Program), regardless of whether the costs are expensed or 

capitalized. Lump sum capital costs (t Ily accrued over several years prior to start up) are not to be reported. Program 

costs associated with strategic load growth activities are also to be excluded. 

Demonstrated reserve base (coal): Acollective term for the sum of coal in both measured and indicated resource 

categories of reliability, representing 100 percent of the in-place coal in those categories as of a certain date. Includes beds 

of bituminuous coal and anthracite 28 or more inches thick and beds of subbituminuous coal 60 or more inches thick that 

can occur at depths of up to 1,000 feet. Includes beds of lignite 60 or more inches thick that can be surface mined. Includes 

also thinner and/or deeper beds that presently are being mined or for which there is evidence that they could be mined 

commercially at a given time. Represents that portion of the identified coal resource from which reserves are calculated. 

Demonstrated reserves: See Energy reserves. 

Demonstrated resources: Same qualifications as identified resources, but include measured and indicated degrees of 

geologic assurance and excludes the inferred. 

Demonstration and test vehicles: Vehicles operated by a motor vehicle dealer solely for the purpose of promoting motor 

vehicle sales or permitting potential purchasers to drive the vehicle for pre-purchase or pre-lease evaluation; or a vehicle 

that is owned and operated bya motor vehicle manufacturer or motor vehicle component manufacturer, or owned or held by 

a university research department, independent testing laboratory, or other such evaluation facility, solely for the purpose of 

evaluating the performance of such vehicles for engineering, research and development, or quality control reasons. 

Demurrage: The charge paid to the vessel owner or operator for detention of a vessel at the port(s) beyond the time 

allowed, usually 72 hours, for loading and unloading. 

Denaturant: Petroleum, typically pentanes plus or conventional motor gasoline, added to fuel ethanol to make it unfit for 

human consumption. Fuel ethanol is denatured, usually prior to transport from the ethanol production facility, by adding 2 to 

5 volume percent denaturant. See Fuel Ethanol, and Fuel Ethanol Minus Denaturant. 

Denatured : Fuel ethanol that is rendered unfit for human consumption by the addition of a petroleum denaturant, typically 

pentanes plus or conventional motor gasoline. Fuel ethanol is usually denatured prior to transport f the ethanol 

production facility, by adding 2- to 5-volume-percent denaturant. 

Dependable capacity: The load-carrying ability of a station or system under adverse conditions for a specified period of 

time. 

Depleted resources: Resources that have been mined; include coal recovered, coal lost in mining, and coal reclassified 

as subeconomic because of mining. 

Depleted storage field: Asub-surface natural geological reservoir, usually a depleted gas or oil field, used for storing 

natural gas. 

Depletion (coal): The subtraction of both tonnage produced and the tonnage lost to mining from identified resources to 

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determine the remaining tonnage as of a certain time. 

Depletion allowance: Aterm for either (1) a periodic assignment to expense of recorded amounts or (2) an allowable 

income tax deduction that is related to the exhaustion of mineral reserves. Depletion is included as one of the elements of 

amortization. When used in that manner, depletion refers only to book depletion. 

Book. The portion of the carrying value (other than the portion associated with tangible assets) prorated in 

each accounting period, for financial reporting purposes, to the extr ted portion of an economic interest in 

wasting natural r 

Tax-cost. A deduction (allowance) under U.S. Federal income taxation normally calculated under a formula 

whereby the adjusted basis of the mineral property is multiplied by a fraction, the numerator of which is the 

number of units of minerals sold during the tax year and the denominator of which is the estimated number of 

units of unextracted minerals remaining at the end of the tax year plus the number of units of minerals sold 

during the tax year. 

Tax-percentage (for Statutory). A deduction (allowance) allowed to certain mineral producers under U.S. 

Federal income taxation calculated on the basis of a specified percentage of gross revenue from the sale of 

minerals from each mineral property not to exceed the lesser of 50 percent of the taxable income from the 

property computed without allowance for depletion. (There are also other limits on percentage depletion on oil 

and gas production.) The taxpayer is entitled to a deduction representing the amount of tax-cost depletion or 

percentage (statutory) depletion, whichever is higher. 

Excess statutory depletion. The excess of estimated statutory depletion allowable as an income tax 

deduction over the amount of cost depletion otherwise allowable as a tax deduction, determined on a total 

enterprise basis. 

Depletion factor: The multiplier applied to the tonnage produced to corn pute depletion. This multiplier takes into account 

both the tonnage recovered and the tonnage lost due to mining. The depletion factor is the reciprocal of the recoveryfactor in 

relation to a given quantity of production. 

Depreciation: See definition for Amortization. 

Depreciation and amortization of property, plant, and equipment: The monthly provision for depreciation and amortization 

(applicable to utility property other than electric plant, electric plant in service, and equipment). 

Depth of deepest production: The depth of the deepest production is the length of the well bore measured (in feet) from 

the surface reference point to the bottom of the open hole or the deepest perforation in the casing of a producing well. 

Derate: A decrease in the available capacity of an electric generating unit, cam m only due to: 

• A system or equipment modification 

• Environmental, operational, or reliability considerations. Causes of generator capacity deratings include high cooling 

water temperatures, equipment degradation, and historical performance during peak demand periods. In this context, a 

derate is ty Ilytemporary and due to transient conditions. 

The term derate can also refer to discounting a portion of a generating units capacityfor planning purposes. 

Deregulation: The elimination of some or all regulations from a previously regulated industry or sector of an industry. 

Design electrical rating (capacity) net: The nominal net electrical output of a nuclear unit, as specified by the utility for the 

purpose of plant design. 

Design head: The achieved river, pondage, or reservoir surface height (forebay elevation) that provides the water level to 

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produce the full flow at the gate of the turbine in order to attain the manufacturer's installed nameplate rating for generation 

capacity. 

Desulfurization: The removal of sulfur, as from molten metals, petroleum oil, or flue gases. 

Development: The preparation of a specific mineral deposit for commercial production; this preparation includes 

construction of access to the deposit and of facilities to extract the minerals. The development process is sometimes 

further distinguished between a preproduction stage and a current stage, with the distinction being made on the basis of 

whether the development work is performed before or after production from the mineral deposit has commenced on a 

commercial scale. 

Development costs: Costs incurred to obtain access to proved reserves and to provide facilities for extracting, treating, 

gathering, and storing the oil and gas. More specifically, development costs, depreciation and applicable operating costs of 

support equipment and facilities, and other costs of development activities, are costs incurred to: 

• Gain access to and prepare well locations for drilling, including surveying well locations for the purpose of 

determining specific development drilling site; clearing ground; draining; road building; and relocating public roads, 

gas lines, and power lines to the extent necessary in developing the proved reserves. 

• Drill and equip development wells, development-t Ils, and service wells, including the costs 

of platforms and of well equipment such as casing, tubing, pumping equipment, and the well head assembly. 

• Acquire, construct, and install production facilities such as lease flow lines, separators, treaters, heaters, manifolds, 

measuring devices, production storage tanks, natural gas cycling and processing plants, and utilitywaste disposal 

systems. 

• Provide improved recoverysystems. 

Development drilling: Drilling done to determine more precisely the size, grade, and configuration of an ore deposit 

subsequent to when the determination is made that the deposit can be commercially developed. Not included are: 

1. secondary development drilling, 

2. solution-mining drilling for production, 

or 

3. production-related underground and open pit drilling done for control of mining operations. 

Development well: Awell drilled within the proved area of an oil or gas reservoir to the depth of a stratigraphic horizon 

known to be productive. Also see Well. 

Diesel fuel: Afuel composed of distillates obtained in petroleum refining operation or blends of such distillates with 

residual oil used in motor vehicles. The boiling point and specific gravity are higher for diesel fuels than for gasoline. 

Diesel fuel system: Diesel engines are internal combustion engines that burn diesel oil rather than gasoline. Injectors are 

used to spray droplets of diesel oil into the combustion chambers, at or near the top of the compression stroke. Ignition 

follows due to the very high temperature of the compressed intake air, or to the use of "glow plugs," which retain heat from 

previous ignitions (spark plugs are not used). Diesel engines are generally more fuel-efficient than gasoline engines but 

must be stronger and heavier because of high compression ratios. 

Diesel-electric plant: Agenerating station that uses diesel engines to drive its electric generators. 

Diffusive transport: The process bywhich particles of liquids or gases move from an area of higher concentration to an 

area of lower concentration. 

Direct access: The ability of a retail customer to purchase electricity or other energy sources directly from a supplier other 

than their traditional supplier. 

Direct control load management: The magnitude of customer demand that can be interrupted at the time of the seasonal 

peak load by direct control of the system operator by interrupting power supply to individual appliances or equipment on 

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customer premises. This type of control usually reduces the demand of residential customers. 

Direct electricity load control: The utility installs a radio-controlled device on the HVAC equipment. During periods of 

particularly heavy use of electricity, the utility will send a radio signal to the building in its service territory with this device and 

turn off the HVAC for a certain period. 

Direct labor hours: Direct labor hours worked by all mining employees at a mining operation during the year. Includes 

hours worked by those employees engaged in production, preparation, development, maintenance, repair, shop or yard 

work management, and technical or engineering work. Excludes office workers. Excludes vacation and leave hours. 

Direct load control: This Demand-Side Management category represents the consumer load that can be interrupted at the 

time of annual peak load bydirect control of the utilitysystem operator. Direct Load Control does not include Interruptible 

Load. This type of control usually involves residential consumers. 

Direct milling cost: Operating costs directly attributable to the processing of ores or other feed materials, including labor, 

supervision, engineering, power, f I, supplies, reagents, and maintenance. 

Direct mining cost: Operating cost directly attributable to the mining of ore, including costs for labor, supervision, 

engineering, power, fuel, supplies, equipment replacement, maintenance, and taxes on production. 

Direct nonprocess end use: Those end uses that may be found on commercial, residential, or other sites, as well as at 

manufacturing establishments. They include heating, ventilation, and air conditioning (HVAC), facility lighting, facility 

support, onsite transportation, conventional electricity generation, and other nonprocess uses. "Direct" denotes that only the 

quantities of electricityor fossil fuel used in their original state (i.e., not transformed) are included in the estimates. 

Direct process end use: Those end uses that are specific to the carrying out of manufacturing. They include process 

heating, process cooling and refrigeration, machine drive, electrochemical processes, and other process uses. "Direct" 

denotes that only the quantities of electricity or fossil f I used in their original state (i.e., not transformed) are included in 

the estimates. 

Direct use: Use of electricity that 

1. is self-generated, 

2. is produced by either the same entity that consumes the power or an affiliate, and 

3. is used in direct support of a service or industrial process located within the same facility or group of facilities that 

house the generating equipment. 

Direct use is exclusive of station use. 

Direct utility cost: A utility cost that is identified with one of the DSM program categories (e.g. Energy Efficiency or Load 

Management). 

Directional (deviated) well: Awell purposely deviated from the vertical, using controlled angles to reach an objective 

location other than directly below the surface location. A directional well may be the original hole or a directional "sidetrack" 

hole that deviates from the original bore at some point below the surface. The new footage associated with directional 

"sidetrack" holes should not be confused with footage resulting from remedial sidetrack drilling. If there is a common bore 

from which two or more wells are drilled, the first complete bore from the surface to the original objective is classified and 

reported as a well drilled. Each of the deviations from the common bore is reported as a separate well. 

Discharged fuel: Irradiated fuel removed from a nuclear reactor during refueling. Also see Spent Fuel. 

Discrete-delivery energy sources: Energy sources that must be delivered to a site. 

Dispatching: The operating control of an integrated electric system involving operations such as (1) the assignment of load 

to specific generating stations and other sources of supply to effect the most economical supply as the total or the 

significant area loads rise or fall (2) the control of operations and maintenance of high-voltage lines, substations, and 

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equipment; (3) the operation of principal tie lines and switching; (4) the scheduling of energytransactions with connecting 

electric utilities. 

Disposition, natural gas: The removal of natural, synthetic, and/or supplemental gas, or any components or gaseous 

mixtures contained therein, from the responding companys facilities within the report State by any means or for any 

purpose, including the transportation of such gas out of the report State. 

Disposition, petroleum: A set of categories used to account for how crude oil and petroleum products are transferred, 

distributed, or removed from the supply stream. The categories include stock change, crude oil losses, refinery inputs, 

exports, and products supplied for domestic consumption. 

Distillate fuel oil: A general classification for one of the petroleum fractions produced in conventional distillation operations. 

It includes diesel f Is and fuel oils. Products known as No. 1, No. 2, and No. 4 diesel f I are used in on-highway diesel 

engines, such as those in trucks and automobiles, as well as off-highway engines, such as those in railroad locomotives 

and agricultural machinery. Products known as No. 1, No. 2, and No. 4 fuel oils are used primarilyfor space heating and 

electric power generation. 

No. 1 Distillate: A light petroleum distillate that can be used as either a diesel fuel (see No. 1 Diesel Fuel) or 

a fuel oil. See No.1 Fuel Oil . 

o No. 1 Diesel Fuel: Alight distillate fuel oil that has distillation temperatures of 550 degrees Fahrenheit at the 

90-percent point and meets the specifications defined in ASTM Specification D 975. It is used in high-speed 

diesel engines, such as those in city buses and similar vehicles. See No. 1 Distillate. 

o No. 1 Fuel Oil: Alight distillate fuel oil that has distillation temperatures of 400 degrees Fahrenheit at the 10-

percent recovery point and 550 degrees Fahrenheit at the 90-percent point and meets the specifications 

defined in ASTM Specification D 396. It is used primarily as fuel for portable outdoor stoves and portable 

outdoor heaters. See No. 1 Distillate. 

No. 2 Distillate: A petroleum distillate that can be used as either a diesel fuel (see No. 2 Diesel Fuel 

definition) or a fuel oil. SeeNo. 2 Fuel oil. 

o No. 2 Diesel Fuel: Afuel that has a distillation temperature of 640 degrees Fahrenheit at the 90-percent 

recovery point and meets the specifications defined in ASTM Specification D 975. It is used in high-speed 

diesel engines, such as those in railroad locomotives, trucks, and automobiles. See No. 2 Distillate. 

o No. 2 fuel oil (heating oil): A distillate fuel oil that has a distillation temperatures of 400 degrees Fahrenheit at 

the 10-percent recovery point and 640 degrees Fahrenheit at the 90-percent recovery point and meets the 

specifications defined in ASTM Specification D 396. It is used in atomizing ty for domestic heating 

or for moderate capacity commercial/industrial burner units. See No. 2 Distillate. 

No. 4 Fuel: A distillate fuel oil made by blending distillate fuel oil and residual fuel oil stocks. It conforms with 

ASTM Specification D 396 or Federal Specification VV-F-815C and is used extensively in industrial plants and 

in commercial burner installations that are not equipped with preheating facilities. It also includes No. 4 

diesel fuel used for low- and medium-speed diesel engines and conforms to ASTM Specification D 975. 

No. 4 Diesel Fuel and No. 4 Fuel Oil: See No. 4 Fuel. 

Distillation unit (atmospheric): The primary distillation unit that processes crude oil (including mixtures of other 

hydrocarbons) at approximately atmospheric conditions. It includes a pipe still for vaporizing the crude oil and a fractionation 

tower for separating the vaporized hydrocarbon components in the crude oil into fractions with different boiling ranges. This 

is done by continuouslyvaporizing and condensing the components to separate higher oiling point material. The selected 

boiling ranges are set by the processing scheme, the properties of the crude oil, and the product specifications. 

Distributed generator: A generator that is located close to the particular load that it is intended to serve. General, but nonexclusive, characteristics of these generators include: an operating strategy that supports the served load; and 

interconnection to a distribution or sub-transmission system (138 kV or less). 

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Distributed/point-of-use water-heating system: Asystem for heating hot water, for other than space heating purposes, 

which is located at more than one space within a building. A point-of-use water heater is located at the faucet and heats 

water only as required for immediate use. Because water is not heated until it is required, this equipment is more energyeff 

Distribution: The delivery of energy to retail customers. 

Distribution provider (electric): Provides and operates the Lwiresi, between the transmission system and the end-use 

customer. For those end-use customers who are served at transmission voltages, the Transmission Owner also serves as 

the Distribution Provider. Thus, the Distribution Provider is not defined bya specific voltage, but rather as performing the 

Distribution function at any voltage. NERC definition 

Distribution system: The portion of the transmission and facilities of an electric system that is dedicated to delivering 

electric energy to an end-user. 

Distribution use: Natural gas used as fuel in the respondent's operations. 

Distributor: A com pany primarily engaged in the sale and delivery of natural and/or supplemental gas directly to 

consumers through a system of mains. 

District chilled water: Chilled water from an outside source used as an energy source for cooling in a building. The water 

is chilled in a central plant and piped into the building. Chilled water maybe purchased from a utility or provided bya central 

physical plant in a separate building that is part of the same multibuilding facility (for example, a hospital complexor 

university). 

District heat: Steam or hot water from an outside source used as an energy source in a building. The steam or hot water is 

produced in a central plant and piped into the building. The district heat maybe purchased from a utility or provided bya 

physical plant in a separate building that is part of the same facility (for example, a hospital complex or university). 

Diversity: The electric utility system's load is made up of many individual loads that make demands upon the system 

usually at different times of the day. The individual loads within the customer classes follow similar usage patterns, but 

these classes of service place different demands upon the facilities and the system grid. The service requirements of one 

electrical system can differ from another by time-of-day usage, facility usage, and/or demands placed upon the system grid. 

Diversity exchange: An exchange of capacity or energy, or both, between systems whose peak loads occur at different 

times. 

Divestiture: The stripping off of one utility function from the others by selling (spinning-off) or in some other way changing 

the ownership of the assets related to that function. Stripping off is most commonly associated with spinning-off generation 

assets so they are no longer owned by the shareholders that own the transmission and distribution assets. 

Docket: Aformal record of a Federal Energy Regulatory Commission proceeding. These records are available for 

inspection and copying bythe public. Each individual case proceeding is identified byan assigned number. 

DOE: Department of Energy. 

Domestic: See United States. 

Domestic inland consumption: Domestic inland consumption is the sum of all refined petroleum products supplied for 

domestic use (excludes international marine bunkers). Consumption is calculated byproduct by adding production, 

imports, crude oil burned directly, and refinery fuel and losses, and then subtracting exports and charges in primary stocks 

(net withdrawals is a plus quantity and net additions is a minus quantity). 

Domestic uranium industry: Collectively, those businesses (whether U.S. or foreign-based) that operate under the laws 

and regulations pertaining to the conduct of commerce within the United States and its territories and possessions and that 

engage in activities within the United States, its territories, and possessions specifically directed toward uranium 

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exploration, development, mining, and milling; marketing of uranium materials; enrichment; fabrication; or acquisition and 

management of uranium materials for use in commercial nuclear powerplants. 

Domestic vehicle producer: An Original Vehicle Manufacturer that assembles vehicles in the United States for domestic 

use. The term "domestic" pertains to the fift , the District of Columbia, common wealths, territories, and possessions 

of the United States. 

Double circuit line: Atransmission line having two separate circuits. Because each carries three-phase power, at least six 

conductors, three per circuit, are required. 

Drainage basin: The land drained by a river system. 

Drawdown: The lowering of the water level of a reservoir as a result of withdrawing water. 

Drawdown (maximum): The distance that the water surface of the reservoir is lowered from the normal full elevation to the 

lowest allowable elevation as the result of the withdrawal of water for the purposes of generating electricity. 

DRB: Demonstrated Reserve Base 

Dredge mining: A m ethod of recovering coal from rivers or streams. 

Drift mine: Amine that opens horizontally into the coal bed or coal outcrop. 

Drilling: The act of boring a hole (1) to determine whether minerals are present in commercially recoverable quantities and 

(2) to accomplish production of the minerals (including drilling to inject fluids). 

• Exploratory. Drilling to locate probable mineral deposits or to establish the nature of geological structures; such 

wells may not be capable of production if minerals are discovered. 

• Developmental. Drilling to delineate the boundaries of a known mineral deposit to enhance the productive capacity 

of the producing mineral property. 

• Directional. Drilling that is deliberately made to depart significantlyfrom the vertical. 

Drilling and equipping of wells: The drilling and equipping of wells through completion of the "christmas tree." 

Drilling arrangement: A contractual agreement under which a working interest owner (assignor) assigns a part of a 

working interest in a property to another party (the assignee) in exchange for which the assignee agrees to develop the 

property. The term may also be applied to an agreement under which an operator assigns fractional shares in production 

from a propertyto participants for cash considerations as a means of acquiring cash for developing the property. Under a 

"disproportionate cost" drilling arrangement, the participants normally pay a greater total share of costs than the total value 

of the fractional shares of the property received in the arrangement. 

Dry (coal) basis: Coal quality data calculated to at heoretical basis in which no moisture is associated with the sample. 

This basis is determined by measuring the weight loss of a sample when its inherent moisture is driven off under 

controlled conditions of low temperature air-drying followed by heating to just above the boiling point of water (104 to 110 

degrees Centigrade). 

Dry bottom boiler: No slag tanks at furnace throat area. The throat area is clear. Bottom ash drops through the throat to the 

bottom ash water hoppers. This design is used where the ash melting temperature is greater than the temperature on the 

furnace wall, allowing for relatively dry furnace wall conditions. 

Dry gas: SeeDry natural gas. 

Dry hole: An exploratory or development well found to be incapable of producing either oil or gas in sufficient quantities to 

justify completion as an oil or gas well. Also seeWell. 

Dry hole charge: The charge-off to expense of a previously capitalized cost upon the conclusion of an unsuccessful drilling 

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effort. 

Dry hole contribution: A payment (either in cash or acreage) that is required by agreement only if a test well is 

unsuccessful and that is made in exchange for well test and evaluation data. 

Dry natural gas: Natural gas which remains after: 1) the liquefiable hydrocarbon portion has been removed from the gas 

stream (i.e., gas after lease, field, and/or plant separation); and 2) any volum es of nonhydrocarbon gases have been 

removed where they occur in sufficient quantityto render the gas unmarketable. Note: Dry natural gas is also known as 

consumer-grade natural gas. The parameters for measurement are cubic feet at 60 degrees Fahrenheit and 14.73 pounds 

per square inch absolute. Also see Natural gas. 

Dry natural gas production: The process of producing consumer-grade natural gas. Natural gas withdrawn from 

reservoirs is reduced byvolumes used at the production (lease) site and by processing losses. Volumes used at the 

production site include (1) the volume returned to reservoirs in cycling, repress uring of oil reservoirs, and conservation 

operations; and (2) gas vented and flared. Processing losses include (1) nonhydrocarbon gases (e.g., water vapor, carbon 

dioxide, helium, hydrogen sulfide, and nitrogen) removed from the gas stream; and (2) gas converted to liquid form, such as 

lease condensate and plant liquids. Volumes of drygas withdrawn from gas storage reservoirs are not considered part of 

production. Dry natural gas production equals marketed production less extraction loss. 

Dry production: See Dry natural gas production. 

DSM: Demand-Side Management 

DTW: Dealer Tank Wagon 

Dual fuel vehicle (1): A motor vehicle that is capable of operating on an alternative fuel and on gasoline or diesel fuel. 

These vehicles have at least two separate fuel systems which inject each fuel simultaneously into the engine combustion 

chamber. 

Dual fuel vehicle (2): A motor vehicle that is capable of operating on an alternative fuel and on gasoline or diesel f I. This 

term is meant to represent all such vehicles whether they operate on the alternative fuel and gasoline/diesel 

simultaneously (e.g., flexible-f I vehicles) or can be switched to operate on gasoline/diesel or an alternative fuel (e.g., bifI vehicles). 

Dual-fired unit: A generating unit that can produce electricity using two or more input fuels. In some of these units, only the 

primary fuel can be used continuously, the alternate fuel(s) can be used only as a start-up fuel or in emergencies. 

Dump energy: Energy generated in a hydroelectric plant by water that cannot be stored or conserved and which energy is in 

excess of the needs of the system producing the energy. 

ABCDEFGHIJKLMNOPQRSTUVWXYZ 

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Browse terms related to these fuel groups: alternative fuels coal electricitynatural gas nuclear petroleum 

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E 

E I containing a mixture of 85 percent ethanol and 15 percent gasoline. SeeMotor gasoline(f )• 

E95: Afuel containing a mixture of 95 percent ethanol and 5 percent gasoline 

EAR: Estimated Additional Resources 

Economy of scale: The principle that larger production facilities have lower unit costs than smaller facilities. 

Effective full-power days: The number of effective full-power days produced by a unit is a measure of the unit's energy 

generation. It is determined using the following ratio Heat generation (planned or actual) in megawatt days thermal (MWdt) 

(dividedby) Licensed thermal power in megawatts thermal (MWt). 

EIA: The Energy Information Administration. An independent agency within the U.S. Department of Energythat develops 

surveys, collects energy data, and analyzes and models energy issues. The Agency must meet the requests of Congress, 

other elements within the Department of Energy, Federal Energy Regulatory Commission, the Executive Branch, its own 

independent needs, and assist the general public, or other interest groups, without taking a policy position. See more 

information about EIA athttp://www.eia.gov/about/ 

EIS: Environmental Impact Statement 

Electric baseboard: An individual space heater with electric resistance coils mounted behind shallow panels along 

baseboards. Electric baseboards rely on passive convection to distribute heated air to the space. 

Electric current: The flow of electric charge. The preferred unit of measure is the ampere. 

Electric energy: The ability of an electric current to produce work, heat, light, or other forms of energy. It is measured in 

kilowatthours. 

Electric expenses: The cost of labor, material, and expenses incurred in operating a facility's prime movers, generators, 

auxiliary apparatus, switching gear, and other electric equipment for each of the points where electricity enters the 

transmission or distribution grid. 

Electric generation: SeeGross generation and Net generation. 

Electric generation industry: Stationary and mobile generating units that are connected to the electric power grid and can 

generate electricity. The electric generation industry includes the "electric power sector" (utility generators and independent 

power producers) and industrial and commercial power generators, including combined-heat-and-power producers, but 

excludes units at single-family dwellings. 

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Electric generator: A facility that produces only electricity ly expressed in kilowatthours (kWh) or megawatthours 

(MWh). Electric generators include electric utilities and independent power producers. 

Electric hybrid vehicle: An electric vehicle that either (1) operates solely on electricity, but contains an internal combustion 

motor that generates additional electricity (series hybrid); or (2) contains an electric system and an internal combustion 

system and is capable of operating on either system (parallel hybrid). 

Electric industry reregulation: The design and implementation of regulatory practices to be applied to the remaining 

traditional utilities after the electric power industry has been restructured. Reregulation applies to those entities that 

continue to exhibit characteristics of a natural monopoly. Reregulation could em ploy the same or different regulatory 

practices as those used before restructuring. 

Electric industry restructuring: The process of replacing a monopolistic system of electric utility suppliers with competing 

sellers, allowing individual retail customers to choose their supplier but still receive delivery over the power lines of the local 

utility. It includes the reconfiguration of vertically-integrated electric utilities. 

Electric motor vehicle: A motor vehicle powered by an electric motor that draws current f le storage 

batteries, fuel cells, photovoltaic arrays, or other sources of electric current. 

Electric non-utility: Any entitythat generates, transmits, or sells electricity, or sells or trades electricityservices and 

products, where costs are not established and recovered by regulatory authority. Examples of these entities include, but are 

not limited to, independent power producers, power marketers and aggregators (both wholesale and retail), merchant 

transmission service providers, self-generation entities, and cogeneration firms with Qualifying Facility Status. 

Electric operating expenses: Summation of electric operation-related expenses, such as operation expenses, 

maintenance expenses, depreciation expenses, amortization, taxes other than income taxes, Federal income taxes, other 

income taxes, provision for deferred income taxes, provision for deferred income-credit, and investment tax credit 

adjustment. 

Electric plant (physical): A facility containing prime movers, electric generators, and auxiliary equipment for converting 

mechanical, chemical, and/or fission energy into electric energy. 

Electric plant acquisition adjustment: The difference between (a) the cost to the respondent utility of an electric plant 

acquired as an operating unit or system by purchase and (b) the depreciated original cost, estimated if not known, of such 

property. 

Electric power: The rate at which electric energy is transferred. Electric power is measured by capacity and is commonly 

expressed in megawatts (MW). 

Electric power grid: Asystem of synchronized power providers and consumers connected bytransm iss ion and 

distribution lines and operated by one or more control centers. In the continental United States, the electric power grid 

consists of three systems the Eastern Interconnect, the Western Interconnect, and the Texas Interconnect. In Alaska and 

Hawaii, several systems encompass areas smaller than the State (e.g., the interconnect serving Anchorage, Fairbanks, 

and the Kenai Peninsula; individual islands). 

Electric power plant: A station containing prime movers, electric generators, and awdliary equipment for converting 

mechanical, chemical, and/or fission energy into electric energy. 

Electric power sector: An energy-consuming sector that consists of electricity only and combined heat and power(CHP) 

plants whose primary business is to sell electricity, or electricity and heat, to the public--i.e., North American Indust. 

lassification System 22 plants. See alsoCombined heat and power (CHP) plantand Electricity only plant. 

Electric power system: An individual electric power entity--a company, an electric cooperative; a public electric supply 

corporation as the Tennessee Valley Authority; a similar Federal department or agency such as the Bonneville Power 

Administration; the Bureau of Reclamation or the Corps of Engineers; a municipally owned electric department offering 

service to the public; or an electric public utility district (a "PUD"); also a jointly owned electric supply project such as the 

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Keystone. 

Electric pump for well water: This pump forces the water from a well below ground level up into the water pipes that 

circulate through the house. When this pump is not working, there is a limited supply of running water in the house. 

Electric rate: The price set for a specified amount and type of electricity by class of service in an electric rate schedule or 

sales contract. 

Electric rate schedule: A statem ent of the electric rate and the terms and conditions governing its application, including 

attendant contract terms and conditions that have been accepted by a regulatory body with appropriate oversight authority. 

Electric system loss: Total energy loss from all causes for an electric utility. 

Electric system reliability: The degree to which the performance of the elements of the electrical system results in power 

being delivered to consumers within accepted standards and in the amount desired. Reliability encom passes two 

concepts, adequacy and security. Adequacy implies that there are sufficient generation and transmission resources 

installed and available to meet projected electrical demand plus reserves for contingencies. Security im plies that the 

system will remain intact operationally (i.e., will have sufficient available operating capacity) even after outages or other 

equipment failure. The degree of reliability may be measured by the frequency, duration, and magnitude of adverse effects 

on consumer service. 

Electric utility: A corporation, person, agency, authority, or other legal entity or instrumentality aligned with distribution 

facilities for delivery of electric energyfor use primarily bythe public. Included are investor-owned electric utilities, municipal 

and State utilities, Federal electric utilities, and rural electric cooperatives. Afew entities that are tariff based and corporately 

aligned with companies that own distribution facilities are also included. 

Electric utility company: See Electric utility. 

Electric utility divestiture: The separation of one electric utility function from others through the selling of the management 

and ownership of the assets related to that function. It is most commonly associated with selling generation assets so they 

are no longer owned or controlled by the shareholders that own the companys transmission and distribution assets. 

Electric utility generator: A generator that is owned by an electric utility, (see definition of electric utility) or a jointly owned 

generator with the greatest share of the generator being electric utility owned. Note: If two or more owners have equal 

shares of ownership in a generator, it is considered to be an electric utility generator if anyone of the owners meets the 

definition of electric utility. 

Electric utility restructuring: The introduction of competition into at least the generation phase of electricity production, with 

a corresponding decrease in regulatory control. 

Electric utility sector: The electric utility sector consists of privately and publicly owned establishments that generate, 

transmit, distribute, or sell electricity primarily for use by the public and that meet the definition of an electric utility. Non utility 

power producers are not included in the electric sector. 

Electric zone: A portion of the grid controlled bythe independent system operator. 

Electrical system energy losses: The amount of energy lost during generation, transmission, and distribution of electricity, 

including plant and unaccounted for use. 

Electricity: Aform of energy characterized bythe presence and motion of elementary charged particles generated by 

friction, induction, or chemical change. 

Electricity broker: An entity that arranges the sale and purchase of electric energy, the transmission of electricity, and/or 

other related services between buyers and sellers but does not take title to any of the power sold. 

Electricity congestion: A condition that occurs when insufficient transmission capacity is available to implement all of the 

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desired transactions simultaneously. 

Electricity demand: The rate at which energy is delivered to loads and scheduling points by generation, transmission, and 

distribution facilities. 

Electricity demand bid: A bid into the power exchange indicating a quantity of energy or an ancillary service that an eligible 

customer is willing to purchase and, if relevant, the maximum price that the customer is willing to pay. 

Electricity generation: The process of producing electric energy or the amount of electric energy produced by transforming 

other forms of energy, commonly expressed in kilowatthours(kWh) or megawatthours (M). 

Electricity generation, gross: See Gross generation. 

Electricity generation, net: See Net generation. 

Electricity only plant: A plant designed to produce electricity only. See also Combined heat and power (CHP) plant. 

Electricity paid by household: The household paid the electric utility company directly for all household uses of electricity 

(such as water heating, space heating, air-conditioning, cooking, lighting, and operating appliances.) Bills paid by a third 

party are not counted as paid bythe household. 

Electricity sales: The amount of kilowatthours sold in a given period of time; usually grouped by classes of service, such 

as residential, commercial, industrial, and other. "Other" sales include sales for public street and highway lighting and other 

sales to public authorities, sales to railroads and railways, and interdepartmental sales. 

Electrochemical process: The direct process end use in which electricity is used to cause a chemical transformation. 

Major uses of electrochemical process occur in the aluminum industry in which alumina is reduced to molten aluminum 

metal and oxygen, and in the alkalies and chlorine industry, in which brine is separated into caustic soda, chlorine, and 

hydrogen. 

Elution: Activities of removing "elutes" a material (uranium) adsorbed on ion exchange resin from the "eluant" solution. 

Emergency: The failure of an electric power system to generate or deliver electric power as normally intended, resulting in 

the cut-off or curtailment of service. 

Emergency backup generation: The use of electric generators only during interruptions of normal power supply. 

Emergency energy: Electric energy provided for a limited duration, intended only for use during emergency conditions. 

Emissions: Anthropogenic releases of gases to the atmosphere. In the context of global climate change, they consist of 

radiatively im portant greenhouse gases (e.g., the release of carbon dioxide during fuel combustion). 

Emissions coefficient: A unique value for scaling emissions to activity data in terms of a standard rate of emissions per 

unit of activity (e.g., pounds of carbon dioxide emitted per Btu of fossil fuel consumed). 

End user: A firm or individual that purchases products for its own consumption and not for resale (i.e., an ultimate 

consumer). 

Ending stocks: Primary stocks of crude oil and petroleum products held in storage as of 12 midnight on the last day of the 

month. Primary stocks include crude oil or petroleum products held in storage at (or in) leases, refineries, natural gas 

processing plants, pipelines, tank farms, and bulk terminals that can store at least 50,000 barrels of petroleum products or 

that can receive petroleum products by tanker, barge, or pipeline. Crude oil that is in-transit bywater from Alaska or that is 

stored on Federal leases or in the Strategic Petroleum Reserve is included. Primary Stocks exclude stocks of foreign origin 

that are held in bonded warehouse storage. 

Energy: The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this 

capability to motion (kinetic energy). Energy has several forms, some of which are easily convertible and can be changed to 

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another form useful for work. Most of the world's convertible energy comes from fossil fuels that are burned to produce heat 

that is then used as a transfer medium to mechanical or other means in order to accomplish tasks. Electrical energy is 

usually measured in kilowatthours, while heat energy is usually measured in British thermal units (Btu). 

Energy assistance program: See Low Income Home EnergyAssistance Program. 

Energy audit: A program carried out by a utility com pany in which an auditor inspects a home and suggests ways energy 

can be saved. 

Energy broker system: Introduced into Florida bythe Public Service Commission, the energy broker system is a system for 

exchanging information that allows utilities to efficiently exchange hourly quotations of prices at which each is willing to buy 

and sell electric energy. For the broker system to operate, utility systems must have in place bilateral agreements between 

all potential parties, must have transmission arrangements between all potential parties, and must have transmission 

arrangements that allow the exchanges to take place. 

Energy charge: That portion of the charge for electric service based upon the electric energy (kWh) consumed or billed. 

Energy conservation features: This includes building shell conservation features, HVAC conservation features, lighting 

conservation features, any conservation features, and other conservation features incorporated by the building. However, 

this category does not include any demand-side management (DSM) program participation bythe building. Any DSM 

program participation is included in the DSM Programs. 

Energy consumption: The use of energy as a source of heat or power or as a raw material input to a manufacturing 

process. 

Energy deliveries: Energygenerated by on electric utilitysystem and delivered to another system through one or more 

transmission lines. 

Energy demand: The requirement for energy as an input to provide products and/or services. 

Energy effects: The changes in aggregate electricity use (measured in megawatthours) for consumers that participate in a 

utility DSM (demand-side management) program. Energy effects represent changes at the consumer's meter (i.e., exclude 

transmission and distribution effects) and reflect only activities that are undertaken specifically in response to utilityadministered programs, including those activities implemented by third parties under contract to the utility. To the extent 

possible, Energy effects should exclude non-program related effects such as changes in energy usage attributable to non 

participants, government-mandated energy-efficiency standards that legislate improvements in building and appliance 

energy usage, changes in consumer behavior that result in greater energy use after initiation in a DSM program, the natural 

operations of the marketplace, and weather and business-cycle adjustments. 

Energy Efficiency: A ratio of service provided to energy input (e.g., lumens to watts in the case of light bulbs). Services 

provided can include buildings-sector end uses such as lighting, refrigeration, and heating: industrial processes; or vehicle 

transportation. Unlike conservation, which involves some reduction of service, energy efficiency provides energy reductions 

without sacrifice of service. May also refer to the use of technology to reduce the energy needed for a given purpose or 

service. 

Energy efficiency, Electricity: Refers to programs that are aimed at reducing the energy used by specific end-use devices 

and systems, typically without affecting the services provided. These programs reduce overall electricity consum ption 

(reported in megawatthours), often without explicit consideration for the timing of program-induced savings. Such savings 

are generally achieved bysubstituting technologically more advanced equipment to produce the same level of end-use 

services (e.g. lighting, heating, motor drive) with less electricity. Examples include high-efficiency appliances, efficient 

lighting programs, high-efficiency heating, ventilating and air conditioning (HVAC) systems or control modifications, efficient 

building design, advanced electric motor drives, and heat recovery systems. 

Energy efficient motors: Are also known as "high-efficiency motors" and "premium motors." They are virtually 

interchangeable with standard motors, but differences in construction make them more energy efficient. 

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Energy exchange: Anytransaction in which quantities of energy are received or given up in return for similar energy 

products. See exchange, electricity troleum; and exchange, natural gas. 

Energy expenditures: The money directly spent by consumers to purchase energy. Expenditures equal the amount of 

energy used by the consumer multiplied by the price per unit paid by the consumer. 

Energy information: Includes (A) all information in whatever form on fuel reserves, extraction, and energy resources 

(including petrochemical feedstocks) wherever located; production, distribution, and consumption of energy and fuels 

wherever carried on; and (B) matters relating to energy and fuels, such as corporate structure and proprietary relationships, 

costs, prices, capital investment, and assets, and other matters directly related there to, wherever they exist. 

Energy Information Administration (EIA): An independent agencywithin the U.S. Department of Energy that develops 

surveys, collects energy data, and does analytical and modeling analyses of energy issues. The Agency must satisfythe 

requests of Congress, other elements within the Department of Energy, Federal Energy Regulatory Commission, the 

Executive Branch, its own independent needs, and assist the general public, or other interest groups, without taking a policy 

position. 

Energy Intensity: A ratio of energy consumption to another metric, typically national gross domestic product in the case of a 

country's energy intensity. Sector-specific intensities may refer to energy consumption per household, per unit of 

commercial floorspace, per dollar value industrial shipment, or another metric indicative of a sector. Improvements in 

energy intensity include energy efficiency and conservation as well as structural factors not related to technology or 

behavior. 

Energy intensity (Commercial Buildings Energy Consumption Survey): The ratio of consumption to floor space. 

Energy loss: Deleted because there is no need for a general term to encompass all forms of energy loss. Terms referring 

to losses specific to particular energy sources are defined separately. 

Energy loss (power): See Power loss. 

Energy management and control system(EMCS): An energy conservation feature that uses mini/microcomputers, 

instrumentation, control equipment, and software to manage a building's use of energyfor heating, ventilation, air 

conditioning, lighting, and/or business-related processes. These systems can also manage fire control, safety, and 

security. Not included as EMCS are time-clock thermostats. 

Energy management practices: Involvement, as a part of the building's normal operations, in energy efficiency programs 

that are designed to reduce the energy used by s pecific end-use systems. This includes the following EMCS, DSM Program 

Participation, EnergyAudit, and a Building Energy Manager. 

Energy Policy Act of 1992 (EPACT): This legislation creates a new class of power generators, exempt wholesale 

generators, that are exempt from the provisions of the Public Holding Company Act of 1935 and grants the authority to the 

Federal Energy Regulatory Commission to order and condition access by eligible parties to the interconnected 

transmission grid. 

Energy production: See production terms associated with specific energy types. 

Energy receipts: Energy brought into a site from another location. 

Energy reserves: Estimated quantities of energy sources that are demonstrated to exist with reasonable certainty on the 

basis of geologic and engineering data (proved reserves) or that can reasonably be expected to exist on the basis of 

geologic evidence that supports projections from proved reserves (probable/indicated reserves). Knowledge of the location, 

quantity, and grade of probable/indicated reserves is generally incomplete or much less certain than it is for proved energy 

reserves. Note: This term is equivalent to "Demonstrated Reserves" as defined in the resource/reserve classification 

contained in the U.S. Geological Survey Circular 831,1980. Demonstrated reserves include measured and indicated 

reserves but exclude inferred reserves. 

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Energy sale(s): The transfer of title to an energy com m odity from a seller to a buyer for a price or the quantity transferred 

during a specified period. 

Energy savings: A reduction in the amount of electricity used by end users as a result of participation in energy eff 

load management programs. 

Energy service provider: An energy entity that provides service to a retail or end-use customer. 

Energy source: Any substance or natural phenomenon that can be consumed or transformed to supply heat or power. 

Examples include petroleum, coal, natural gas, nuclear, biomass, electricity, wind, sunlight, geothermal, water movement, 

and hydrogen in fuel cells. 

Energy supplier: Fuel companies supply lectricity, natural gas, fuel oil, kerosene, or LPG (liquefied petroleum gas) to 

the household. 

Energy supply: Energy made available for future disposition. Supply can be considered and measured from the point of 

view of the energy provider or the receiver. 

Energy used in the home: For electricity or natural gas, the quantity is the amount used by the household during the365- or 

366-day period. For fuel oil, kerosene, and liquefied petroleum gas (LPG), the quantity consists of fuel purchased, not f I 

consumed. If the level off I in the storage tank was the same at the beginning and end of the annual period, then the 

quantity consumed would be the same as the quantity purchased. 

Energy-use sectors: A group of major energy-consuming components of U.S. society developed to measure and analyze 

energy use. The sectors most commonly referred to in EIA are: residential, commercial, industrial, transportation, and 

electric power. 

Energy-weighted industrial output: The weighted sum of real output for all two-digit Standard Industrial Class ification(SIC) 

manufacturing industries plus agriculture, construction, and mining. The weight for each industry is the ratio between the 

quantity of end-use energy consumption to the value of real output. 

Engine size: The total volume within all cylinders of an engine when pistons are at their lowest positions. The engine is 

usually measured in "liters" or "cubic inches of displacement (CID)." Generally larger engines result in greater engine 

power, but less fuel efficiency. There are 61.024 cubic inches in a liter. 

Enriched uranium: Uranium in which the U-235 isotope concentration has been increased to greater than the 0.711 

percent U-235 (by weight) present in natural uranium. 

Enrichment feed deliveries: Uranium that is shipped under contract to a supplier of enrichment services for use in 

preparing enriched uranium product to a specified U-235 concentration and that ultimatelywill be used as fuel in a nuclear 

reactor. 

Enrichment tails assay: A measure of the amount of fissile uranium (U-235) remaining in the waste stream from the 

uranium enrichment process. The natural uranium "feed" that enters the enrichment process generally contains 0.711 

percent (byweight) U-235. The "product stream" contains enriched uranium (more than 0.711 percentU-235) and the 

"waste" or "tails" stream contains depleted uranium (less than 0.711 percent U-235). At the historical enrichment tails 

assay of 0.2 percent, the waste stream would contain 0.2 percent U-235. A higher enrichment tails assay requires more 

uranium feed (thus permitting natural uranium stockpiles to be decreased), while increasing the output of enriched material 

for the same energy expenditure. 

Environmental impact statement: A report that documents the information required to evaluate the environmental impact of 

a project. It informs decision makers and the public of the reasonable alternatives that would avoid or minimize adverse 

impacts or enhance the quality of the environment. 

Environmental protection agency (EPA) certification files: Computer files produced by EPA for analysis purposes. For 

each vehicle make, model and year, the files contain the EPA test MPGs (city, highway, and 55/45 composite). These MPG's 

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are associated with various combinations of engine and drive-train technologies (e.g., number of cylinders, engine size, 

gasoline or diesel fuel, and automatic or manual transmission). These files also contain information similar to that in the 

DOE/EPA Gas Mileage Guide, although the MPGs in that publication are adjusted for shortfall. 

Environmental restoration: Although usually described as "cleanup," this function encompasses a wide range of activities, 

such as stabilizing contaminated soil; treating groundwater; decommissioning process buildings, nuclear reactors, 

chemical separations plants, and many other facilities; and exhuming sludge and buried drums of waste. 

Environmental restrictions: In reference to coal accessibility, land-use restrictions that constrain, postpone, or prohibit 

mining in order to protect environmental resources of an area; for example, surface- or ground water qualitylity 

affected by mining, or plants or animals or their habitats. 

EOR: Enhanced Oil Recovery 

EPA: Environmental Protection Agency 

EPA certification: A permanent label on fireplace inserts and freestanding wood stoves manufactured after July1 , 1988, 

indicating that the equipment meets EPAstandards for clean burning. 

EPA composite MPG: The harmonic mean of the EPAcity and highway MPG (miles per gallon), weighted under the 

assumption of 55 percent city driving and 45 percent highway driving. 

EPACT: Energy Policy Act of 1992 

Equilibrium cycle: An analytical term that refers to fuel cycles that occur after the initial one or two cycles of a reactor's 

operation. For a given type of reactor, equilibrium cycles have similar fuel characteristics. 

Equity (financial): Ownership of shareholders in a corporation represented by stock. 

E I: The sum of capital f tained earnings and the issuance of stock. 

E I: The proportion of production that a concession owner has the legal and contractual right to retain. 

E lidated affiliates: Acorn panYs proportional share (based on ownership) of the net earnings 

or losses of an unconsolidated affiliate. 

Establishment: An economic unit, generally, at a single physical location where business is conducted or where services 

or industrial operations are performed. However, "establishment" is not synonymous with "building." 

Estimated additional resources (EAR): The uranium in addition to reasonable assured resources (RAR) that is expected 

to occur, mostly on the basis of direct geological evidence, in extensions of well-explored deposits, little-explored deposits, 

and undiscovered deposits believed to exist along a well-defined geologic trend with known deposits, such that the 

uranium can subsequently be recovered within the given cost ranges. Estimates of tonnage and grade are based on 

available sampling data and on knowledge of the deposit characteristics as determined in the best known parts of the 

deposit or in similar deposits. EAR correspond to DOE's Probable Potential Resource Category. 

ETBE: ethyl tertiary butyl ether 

ETBE (ethyl tertiary butyl ether): (CH3)3COC2H: An oxygenate blend stock formed by the catalytic etherification of 

isobutylene with ethanol. 

Ethane (C2H6): A normally gaseous straight-chain hydrocarbon. It is a colorless paraffinic gas that boils at a temperature of 

-127.48 degrees Fahrenheit. It is extracted from natural gas and refinery gas streams. 

Ethanol (C2H5OH): Aclear, colorless, flammable alcohol. Ethanol is ty Ily produced biologicallyfrom biomass 

feedstocks such as agricultural crops and cellulosic residues from agricultural crops or wood. Ethanol can also be 

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produced chemicallyfrom ethylene. SeeBiomass, Fuel Ethanol, and Fuel Ethanol Minus Denaturant. 

Ether: A generic term applied to a group of organic chemical compounds composed of carbon, hydrogen, and oxygen, 

characterized by an oxygen atom attached to two carbon atoms (e.g., methyl tertiary butyl ether). 

Ethylene: An olefinic hydrocarbon recovered from refinery processes or petrochemical processes. Ethylene is used as a 

petrochemical feedstock for numerous chemical applications and the production of consumer goods. 

Ethylene dichloride: A colorless, oily liquid used as a solvent and fumigant for organic synthesis, and for ore flotation. 

EU: European Union 

Eurasia: The physical land mass containing the continents of Europe and Asia. For Energy Information Administration 

reporting, it includes the former parts of theUnion of Soviet Socialist Republics (U.S.S.R): Armenia, Azerbaijan, Belarus, 

Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and 

Uzbekistan. 

Evacuated-tube collector: A collector in which solar thermal heat is captured by use of a collector fluid that flows through 

an absorber tube contained inside an evacuated glass tube. 

Evaporation pond: A containment pond (that preferably has an impermeable lining of clay or synthetic material such as 

hypalon) to hold liquid wastes and to concentrate the waste through evaporation. 

Evaporative cooler (swamp cooler): An air-cooling unit that turns air into moist, cool air by saturating the air with water 

vapor. It does not cool air by use of a refrigeration unit. 

EWG: Exempt Wholesale Generator 

Excess statutory depletion: The excess of estimated statutory depletion allowable as an income tax deduction over the 

amount of cost depletion otherwise allowable as a tax deduction, determined on a total enterprise basis. 

Exchange: Seeenergy exchange. 

Exchange agreement: A contractual agreement in which quantities of crude oil, petroleum products, natural gas, or 

electricity are delivered, either directly or through intermediaries, from one companyto another company, in exchange for the 

delivery by the second companyto the first company of an equivalent volume or heat content. The exchange may take place 

at the same time and location or at different times and/or locations. Such agreements may also involve the payment of 

cash. Note: EIA excludes volumes sold through exchange agreements to avoid double counting of data. Seeenergy 

exchange. 

Exchange energy: Seeexchange, electricity. 

Exchange, electricity: Atype of energy exchange in which one electric utility agrees to supply electricity to another. 

Electricity received is returned in kind at a later time or is accumulated as an energy balance until the end of a specified 

period, after which settlement may be made by monetary payment. Note: This term is also referred to asexchange energy. 

Exchange, natural gas: Atype of energy exchange in which one company agrees to deliver gas, either directly or through 

intermediaries, to another company at one location or in one time period in exchange for the delivery by the second 

company to the first company of an equivalent volume or heat content at a different location or time period. Note: Such 

agreements mayor may not include the payment of fees in dollar or volumetric amounts. 

Exchange, petroleum: Atype of energy exchange in which quantities of crude oil or any petroleum product(s) are received 

or given up in return for other crude oil or petroleum products. It includes reciprocal sales and purchases. 

Exchange, power: Delete in favor of the already-defined term exchange energy, which should be renamed exchange 

electricity or exchange, electricity. 

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Exempt wholesale generator (EWG): Wholesale generators created under the 1992 Energy Policy Act that are exempt from 

certain financial and legal restrictions stipulated in the Public Utilities Holding Com panyAct of 1935. 

Exhaust fan: Small fans located in the wall or ceiling that exhaust air, odors, and moisture from the bathroom, kitchen, or 

basement to the outside. 

Expenditure: The incurrence of a liability to obtain an asset or service. 

Expenditures per million Btu: The aggregate ratio of a group of buildings' total expenditures for a given fuel to the total 

consumption of that f I. 

Expenditures per square foot: The aggregate ration of a group of buildings' total expenditures for a given fuel to the total 

floor space in those buildings. 

Exploration drilling: Drilling done in search of new mineral deposits, on extensions of known ore deposits, or at the 

location of a discovery up to the time when the company decides that sufficient ore reserves are present to justify 

commercial exploration. Assessment drilling is reported as exploration drilling. 

Exploratory well: A hole drilled a) to find and produce oil or gas in an area previously considered unproductive area; b) to 

find a new reservoir in a known field, i.e., one previously producing oil and gas from another reservoir, or c) to extend the 

limit of a known oil or gas reservoir. 

Exports: Shipments of goods from within the 50 States and the District of Columbia to U.S. possessions and territories or 

to foreign countries. 

Extensions: Any new reserves credited to a previously producing reservoir because of enlargement of its proved area. This 

enlargement in proved area is usually due to new well drilling outside of the previously known productive limits of the 

reservoir. 

Extensions, discoveries, and other additions: Additions to an enterprise's proved reserves that result from (1) extension of 

the proved acreage of previously discovered (old) reserves through additional drilling in periods subsequent to discovery 

and (2) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields. 

Externalities: Benefits or costs, generated as a byproduct of an economic activity, that do not accrue to the parties involved 

in the activity. Environmental externalities are benefits or costs that manifest themselves through changes in the physical or 

biological environment. 

Extraction loss: The reduction in volume of natural gas due to the removal of natural gas liquid constituents such as 

ethane, propane, and butane at natural gas processing plants. 

Extractive industries: Industries involved in the activities of (1) prospecting and exploring for wasting (non-regenerative) 

natural resources, (2) acquiring them, (3) f loring them, (4) developing them, and (5) producing (extracting) them 

from the earth. The term does not encompass the industries of forestry, fishing, agriculture, animal husbandry, or any 

others that might be involved with resources of a regenerative nature. 

Extraordinary income deductions (electric utility): Those items related to transactions of a nonrecurring nature that are 

not typical or customary business activities of the utility and that would significantlydistort the current year's net income if 

reported other than as extraordinary items. 

ABCDEFGHIJKLMNOPQRSTUVWXYZ 

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U.S. Energy Information 

Administration 

Glossary 

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Search glossary terms: 

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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

renewable 

F 

F.A.S.: SeeFree Alongside Ship. 

f.a.s. value: Free alongside shipvalue. The value of a commodity at the port of exportation, generally including the purchase 

price plus all charges incurred in placing the commodity alongside the carrier at the port of exportation in the countr 

F.O.B: SeeFree On Board. 

f.o.b. price: The price actually charged at the producing countr t of loading. The reported price should be after 

deducting any rebates and discounts or adding premiums where applicable and should be the actual price paid with no 

adjustment for credit terms. 

f.o.b. value (coal): Free-on-board value. This is the value of coal at the coal mine or of coke and breeze at the coke plant 

without any insurance or freight transportation charges added. 

Fabricated fuel: Fuel assemblies composed of an array of fuel rods loaded with pellets of enriched uranium dioxide. 

Facilities charge: An amount to be paid bythe customer in a lump sum, or periodically as reimbursement for facilities 

furnished. The charge may include operation and maintenance as well as fixed costs. 

Facility: An existing or planned location or site at which prime movers, electric generators, and/or equipment for converting 

mechanical, chemical, and/or nuclear energy into electric energy a resituated or will be situated. Afacility may contain more 

than one generator of either the same or different prime mover type. For a cogenerator, the facility includes the industrial or 

commercial process. 

Fahrenheit: A tem perature scale on which the boiling point of water is at 212 degrees above zero on the scale and the 

freezing point is at 32 degrees above zero at standard atmospheric pressure. 

Failure or hazard: Any electric power supply equipment or facility failure or other event that, in the judgment of the reporting 

entity, constitutes a hazard to maintaining the continuity of the bulk electric power supply system such that a load reduction 

action may become necessary and reportable outage may occur. Types of abnormal conditions that should be reported 

include the imposition of a special operating procedure, the extended purchase of emergency power, other bulk power 

system actions that may be caused by a natural disaster, a major equipment failure that would impact the bulk power 

supply, and an environmental and/or regulatory action requiring equipment outages. 

Farm out (in) arrangement: An arrangement, used primarily in the oil and gas industr lessee of 

mineral rights (the first party) assigns a working interest to an operator (the second party), the consideration for which is 

specified exploration and/or development activities. The first party retains an overriding royalty or other type of economic 

interest in the mineral production. The arrangement from the viewpoint of the second party is termed a "farm-in 

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arrangement." 

Farm use: Energy use at establishments where the primary activity is growing crops and/or raising animals. Energy use by 

all facilities and equipment at these establishments is included, whether or not it is directly associated with growing crops 

and/or raising animals. Common types of energy-using equipment include tractors, irrigation pumps, crop dryers, smudge 

pots, and milking machines. Facility energy use encompasses all structures at the establishment, including the farm 

house. 

FASB: Financial Accounting Standards Board 

Fast breeder reactor (F ): A reactor in which the fission chain reaction is sustained primarily by fast neutrons rather than 

by thermal or intermediate neutrons. Fast reactors require little or no moderator to slow down the neutrons from the speeds 

at which they are ejected from fissioning nuclei. This type of reactor produces more fissile material than it consumes. 

FBR: Fast Breeder Reactor 

Federal coal lease: A lease granted to a mining company to produce coal f land owned and administered by the 

Federal Government in exchange for royalties and other revenues. 

Federal electric utility: A utility that is either owned or financed by the Federal Government. 

Federal Energy Regulatory Commission (FERC): The Federal agency with jurisdiction over interstate electricity sales, 

wholesale electric rates, hydroelectric licensing, natural gas pricing, oil pipeline rates, and gas pipeline certification. FERC 

is an independent regulatoryagencywithin the Department of Energy and is the successor to the Federal Power 

Commission. 

Federal Power Act: Enacted in 1920, and amended in1935, the Act consists of three parts. The first part incorporated the 

Federal Water Power Act administered by the former Federal Power Commission, whose activities were confined almost 

entirely to licensing non-Federal hydroelectric projects. Parts II and III were added with the passage of the Public Utility Act. 

These parts extended the Act's jurisdiction to include regulating the interstate transmission of electrical energy and rates for 

its sale as wholesale in interstate commerce. The Federal Energy Regulatory Commission is now charged with the 

administration of this law. 

Federal Power Commission (FPC): The predecessor agency of the Federal Energy Regulatory Commission. The Federal 

Power Commission was created by an Act of Congress under the Federal Water Power Act on June 10, 1920. It was 

charged originallywith regulating the electric power and natural gas industries. It was abolished on September 30, 1977, 

when the Department of Energywas created. Its functions were divided between the Department of Energy and the Federal 

Energy Regulatory Commission, an independent regulatory agency. 

Federal region: In a Presidential directive issued in 1969, various Federal agencies (among them the currentlydesignated 

Department of Health and Human Services, the Department of Labor, the Office of Economic Opportunity, and the Small 

Business Administration) were instructed to adopt a uniform field system of 10 geographic regions with common 

boundaries and headquarters cities. The action was taken to correct the evolution of fragmented Federal f Id organization 

structures that each agency or component created independently, usuallywith little reference to other agencies' 

arrangements. Most Federal domestic agencies or their components have completed realignments and relocations to 

conform to the Standard Federal Administration Regions (SFARs). 

Fee interest: The absolute, legal possession and ownership of land, property, or rights, including mineral rights. Afee 

interest can be sold (in its entirety or in part) or passed on to heirs or successors. 

Feeder line: An electrical line that extends radiallyfrom a distribution substation to supply electrical energywithin an electric 

area or sub-area. 

FER Federal Energy Regulatory Com mission 

FER lines: A corn pilation of the Federal Energy Regulatory Commission's enabling statutes; procedural and 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

program regulations; and orders, opinions, and decisions. 

Fertile material: Material that is not itself fissionable bythermal neutrons but can be converted to fissile material by 

irradiation. The two principal fer le materials are uranium-238 andthorium-232. 

FGD: Flue-Gas Desulfurization 

Feld: An area consisting of a single reservoir or multiple reservoirs all grouped on, or related to, the same individual 

geological structural feature and/or stratigraphic condition. There maybe two or more reservoirs in a field that are separated 

vertically by intervening impervious strata or laterally by local geologic barriers, or by both. 

Feld area: A geographic area encompassing two or more pools that have a common gathering and metering system, the 

reserves of which are reported as a single unit. This concept applies primarilyto the Appalachian region. 

Feld discovery year: The calendar year in which a field was first recognized as containing economically recoverable 

accumulations of oil and/or gas. 

Feld production: Represents crude oil production on leases, natural gas liquids production at natural gas processing 

plants, new supply of other hydrocarbons/oxygenates and motor gasoline blending components, and fuel ethanol blended 

into finished motor gasoline. 

Feld separation facility: A surface installation designed to recover lease condensate from a produced natural gas stream 

usually originating from more than one lease and managed by the operator of one or more of these leases. 

Fle rate schedule: The rate for a particular electric service, including attendant contract terms and conditions, accepted for 

filing bya regulatory bodywith appropriate oversight authority. 

Fling: Anywritten application, complaint, declaration, petition, protest, answer, motion, brief, exception, rate schedule, or 

other pleading, amendment to a pleading, document, or similar paper that is submitted to a utility corn mission. 

Anal order: Afinal ruling by FERC that terminates an action, decides some matter litigated by the petitioning parties, 

operates to some right, or completely disposes of the subject matter. 

Fnancial Accounting Standards Board (FASB): An independent board responsible, since 1973, for establishing generally 

accepted accounting principles. Its official pronouncements are called "Statements of Financial Accounting Standards" and 

"Interpretations of Financial Accounting Standards." 

Fnished leaded gasoline: Contains more than 0.05 gram of lead per gallon or more than 0.005 gram of phosphorus per 

gallon. Premium and regular grades are included, depending on the octane rating. Includes leaded gasohol. Blendstock is 

excluded until blending has been completed. Alcohol that is to be used in the blending of gasohol is also excluded. 

Fnished motor gasoline: See Motor gasoline (finished). 

Arm: An association, company, corporation, estate, individual, joint venture, partnership, or sole proprietorship, or any other 

entity zed, including (a) charitable or educational institutions; (b) the Federal Government, including 

corporations, departments, Federal agencies, and other instrumentalities; and State and local governments. Afirm may 

consist of (1) a parent entity luding the consolidated and unconsolidated entities (if any) that it directly or indirectly 

controls; (2) a parent and its consolidated entities only (3) an unconsolidated entity or (4) any part or combination of the 

above. 

Firm power: Power or power-producing capacity, intended to be available at all times during the period covered bya 

guaranteed commitment to deliver, even under adverse conditions. 

Frst purchase (of crude oil): An equity (not custody) transaction commonly associated with the transfer of ownership of 

crude oil coupled with the physical removal of the crude oil f (lease) for the first time. Afirst purchase normally 

occurs at the time and place of ownership transfer where the crude oil volume sold is measured and recorded on a run 

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ticket or other similar physical evidence of purchase. The reported price is the first purchase average cost paid by the 

purchaser, allowing for any adjustments (deductions or premiums) passed on to the producer or royalty owner. 

First purchase price: The price for domestic crude oil reported by the company that owns the crude oil the first time it is 

removed from the lease boundary. 

Fiscal y The U.S. Government's f I year runs from October 1 through September 30. The fiscal year is designated by 

the calendar year in which it ends; e.g., fiscal year 2002 begins on October 1, 2001 and ends on September 30, 2002 

Fissile material: Material that can be caused to undergo atomic fission when bombarded by neutrons. The most important 

fissionable materials are uranium-235, plutonium-239, and uranium-233. 

Fission: The process whereby an atomic nucleus of appropriate type, after capturing a neutron, splits into (generally) two 

nuclei of lighter elements, with the release of substantial amounts of energy and two or more neutrons. 

Axed asset turnover: A ratio of revenue to fixed assets which is a measure of the productivity and efficiency of property, 

plant, and equipment in generating revenue. A high turnover reflects positively on the entity's ability to utilize properly its fixed 

assets in business operations. 

Fixed assets: Tangible property used in the operations of an entityt not expected to be consumed or converted into cash 

in the ordinary course of events. With a life in excess of one year, not intended for resale to customers, and subject to 

depreciation (with the exception of land), they are usually referred to as property, plant, and equipment. 

Fixed carbon: The nonvolatile matter in coal minus the ash. Fixed carbon is the solid residue other than ash obtained by 

prescribed methods of destructive distillation of a coal. Fixed carbon is the part of the total carbon that remains when coal is 

heated in a closed vessel until all matter is driven off. 

Axed charge coverage: The ratio of earnings available to pay so-called fixed charges to such fixed charges. Fixed charges 

include interest on funded debt, including leases, plus the related amortizations of debt discount, premium, and expense. 

Earnings available for fixed charges maybe computed before or after deducting income taxes. Occasionally credits for the 

"allowance for funds used during construction" are excluded from the earnings figures. The precise procedures followed in 

calculating fixed charges or interest coverages varywidely. 

Axed cost (expense): An expenditure or expense that does not vary with volume level of activity. 

Axed operating costs: Costs other than those associated with capital investment that do not varywith the operation, such 

as maintenance and payroll. 

Rare: Atall stack equipped with burners used as a safety device at wellheads, refining facilities, gas processing plants, 

and chemical plants. Flares are used for the combustion and disposal of combustible gases. The gases are piped to a 

remote, usually elevated, location and burned in an open flame in the open air using a specially designed burner tip, 

auxiliaryfuel, and steam or air. Combustible gases are flared most often due to emergency relief, overpressure, process 

upsets, startups, shutdowns, and other operational safety reasons. Natural gas that is uneconomical for sale is also flared. 

Often natural gas is flared as a result of the unavailability of a method for transporting such gas to markets. 

Flared natural gas: See flare. 

Flat and meter rate schedule: An electric rate schedule consisting of two components, the first of which is a service charge 

and the second a price for the energy consumed. 

Flat demand rate schedule: An electric rate schedule based on billing demand that provides no charge for energy. 

Rat plate pumped: A medium-temperature solar thermal collector that t Ily consists of a metal frame, glazing, 

absorbers (usually metal), and insulation and that uses a pumped liquid as the heat-transfer medium predominant use is 

in water-heating applications. 

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Fleet vehicle: Any motor vehicle a company owns or leases that is in the normal operations of a corn pany. Vehicles which 

are used in the normal operation of a company, but are owned by company employees are not fleet vehicles. If a company 

provides services in addition to providing natural gas, only those vehicles that are used by the natural gas provider portion of 

a company should be counted as fleet vehicles. Vehicles that are considered "off-road" (e.g., farm or construction vehicles) 

or demonstration vehicles are not to be counted as fleet vehicles. Fleet vehicles include gasoline/diesel powered vehicles 

and alternative-f I vehicles. 

Flexible fuel vehicle: A vehicle that can operate on 

1. alternative fuels (such as M85 or E85) 

2. 100-percent petroleum-based fuels 

3. any mixture of an alternative fuel (or fuels) and a petroleum-based fuel. 

Flexible fuel vehicles have a single fuel system to handle alternative and petroleum-based fuels. 

Flexible fuel vehicle and variable fuel vehicle are synonymous terms. 

Flexicoking: Athermal cracking process which converts heavy hydrocarbons such as crude oil, tar sands bitumen, and 

distillation residues into light hydrocarbons. Feed stocks can be any pumpable hydrocarbons including those containing 

high concentrations of sulftals. 

Floor (coal): The upper surface of the stratum underly I seam. In coals that were formed in persistent swamp 

environments, the floor is typically a bed of clay, known as "underclay," representing the soil in which the trees or other coalforming swamp vegetation was rooted. 

Floor price: A price specified in a market-price contract as the lowest purchase price of the uranium, even if the market 

price falls below the specified price. The floor price maybe related to the seller's production costs. 

Floor space: The area enclosed by exterior walls of a building, including parking areas, basements, or other floors 

belowground level. It is measured in square feet. 

Floor, wall, or pipeless furnace: Space-heating equipment consisting of a ductless combustor or resistance unit, having 

an enclosed chamber where fuel is burned or where electrical-resistance heat is generated to warm the rooms of a 

building. Afloor furnace is located below the floor and delivers heated air to the room immediately above or (if under a 

partition) to the room on each side. Awall f tailed in a partition or in an outside wall and delivers heated air to 

the rooms on one or both sides of the wall. A pipeless furnace is installed in a basement and delivers heated air through a 

large register in the floor of the room or hallway immediately above. 

Flow control: The laws, regulations, and economic incentives or disincentives used bywaste managers to direct waste 

generated in a specific geographic area to a designated landfill, recycling, or waste-to-energy facility. 

Flue: An enclosed passage wayfor directing products of combustion to the atmosphere. 

Flue gas desulfurization: Equipment used to remove sulf ler plant before 

discharge to the atmosphere. Also referred to as scrubbers. Chemicals such as lime are used as scrubbing media. 

Flue-gas desulfurization unit (scrubber): Equipment used to remove sulf the combustion gases of a boiler 

plant before discharge to the atmosphere. Chemicals such as lime are used as the scrubbing media. 

Flue-gas particulate collector: Equipment used to remove fly ash from the combustion gases of a boiler plant before 

discharge to the atmosphere. Particulate collectors include electrostatic precipitators, mechanical collectors (cyclones), 

fabric filters (baghouses), and wet scrubbers. 

Fluid catalytic cracking: The refining process of breaking down the larger, heavier, and more complex hydrocarbon 

molecules into simpler and lighter molecules. Catalytic cracking is accomplished bythe use of a catalytic agent and is an 

effective process for increasing the yield of gasoline from crude oil. Catalytic cracking processes fresh feeds and recycled 

feeds. 

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Fluid coking: A therm al cracking process utilizing the fluidized-solids technique to remove carbon (coke) for continuous 

conversion of heavy, low-grade oils into lighter products. 

Fluidized-bed combustion: A method of burning particulate fuel, such as coal, in which the amount of air required for 

combustion far exceeds that found in conventional burners. The fuel particles are continuallyfed into a bed of mineral ash in 

the proportions of 1 part fuel to 200 parts ash, while a flow of air passes up through the bed, causing it to act like a turbulent 

fluid. 

Fluorescent lamp: Aglass enclosure in which light is produced when electricity is passed through mercuryvapor inside 

the enclosure. The electricity creates a radiation discharge that strikes a coating on the inside surface of the enclosure, 

causing the coating to glow. Note: Traditional fluorescent lamps are usually straight or circular white glass tubes used in 

fixtures specially designed for them. A newer type of fluorescent lamp, the compact fluorescent lamp, takes up much less 

room, comes in many differently-shaped configurations, and is designed to be used in some fixtures originally intended to 

house in candescent lamps. 

Fluorescent light bulbs: These are usually long, narrow, white tubes made of glass coated on the inside with fluorescent 

material, which is connected to a fixture at both ends of the light bulb; some are circular tubes. The light bulb produces light 

bypassing electricity through mercury vapor, which causes the fluorescent coating to glow or fluoresce. 

Fluorescent lighting other than compact fluorescent bulbs: In fluorescent lamps, energy is converted to light by using an 

electric charge to "excite" gaseous atoms within a fluorescent tube. Common types are "cool white," "warm white," etc. 

Special energy efficient fluorescent lights have been developed that produce the same amount of light while consuming 

less energy. Note: for definition of compact fluorescent bulbs, go to compact fluorescent bulbs. 

Flux material: A substance used to promote fusion, e.g., of metals or minerals. 

Fly ash: Particulate matter mainlyfrom coal ash in which the particle diameter is less than 1 x104 meter. This ash is 

removed from the flue gas using flue gas particulate collectors such as fabric filters and electrostatic precipitators. 

FME: Free Market Economies. Countries that are members of the Council for Mutual Economic Assistance (CMEA) are not 

included. 

Footage drilled: Total footage for wells in various categories, as reported for anyspecified period, includes (1)the deepest 

total depth (length of well bores) of all wells drilled from the surface, (2) the total of all bypassed footage drilled in 

connection with reported wells, and (3) all new footage drilled for directional sidetrack wells. Footage reported for directional 

side-track wells does not include footage in the common bore that is reported as footage for the original well. In the case of 

old wells drilled deeper, the reported footage is that which was drilled below the total depth of the old well. 

Forced outage: The shutdown of a generating unit, transmission line, or other facility for emergency reasons or a condition 

in which the generating equipment is unavailable for load due to unanticipated break-down. 

Foreign access: Refers to proved reserves of crude, condensate, and natural gas liquids applicable to long-term supply 

agreements with foreign governments or authorities in which the company or one of its affiliates acts as producer. 

Foreign currency transaction gains and losses: Gains or losses resulting from the effect of exchange rate changes on 

transactions denominated in currencies other than the functional currency (for example, a U.S. enterprise may borrow 

Swiss francs or a French subsidiary may have a receivable denominated in kroner from a Danish customer). Gains and 

losses on those foreign currency transactions are generally included in determining net income for the period in which 

exchange rates change unless the transaction hedges a foreign currency commitment or a net investment in a foreign 

entity. Intercom pany transactions of a long-term investment nature are considered part of a parent's net investment and 

hence do not give rise to gains or losses. 

Foreign currency translation effects: Gains or losses resulting from the process of expressing amounts denominated or 

measured in one currency in terms of another currency by use of the exchange rate between the two currencies. This 

process is generally required to consolidate the financial statements of foreign affiliates into the total company financial 

statements and to recognize the conversion of foreign currency or the settlement of a receivable or payable denominated in 

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foreign currency at a rate different from that at which the item is recorded. Translation adjustments are not included in 

determining net income, but are disclosed as separate components of consolidated equity. 

Foreign operations: These are operations that are located outside the United States. Determination of whether an 

enterprise's mobile assets, such as offshore drilling rigs or ocean-going vessels, constitute foreign operations should 

depend on whether such assets are normally identified with operations located outside the United States. 

Foreign-controlled firms (coal): Foreign-controlled firms are U.S. coal producers with more than 50 percent of their stock 

or assets owned by a foreign firm. 

Forward cost (1): Forward costs are those operating and capital costs yet to be incurred at the time an estimate of 

reserves is made. Profits and "sunk" costs, such as past expenditures for property acquisition, exploration, and mine 

development, are not included. Therefore, the various forward-cost categories are independent of the market price at which 

uranium produced from the reserves would be sold. 

Forward cost (2): The operating and capital costs still to be incurred in the production of uranium from in-place reserves. 

By using forward costing, estimates for reserves for ore deposits in differing geological settings and status of development 

can be aggregated and reported for selected cost categories. Included are costs for labor, materials, power and fuel, 

royalties, payroll taxes, insurance, and applicable general and administrative costs. Excluded from forward cost estimates 

are prior expenditures, if any, incurred for property acquisition, exploration, mine development, and mill construction, as well 

as income taxes, profit, and the cost of money. Forward costs are neither the full costs of production nor the market price at 

which the uranium, when produced, might be sold. 

Forward costs (uranium): The operating and capital costs that will be incurred in anyfuture production of uranium from inplace reserves. Included are costs for labor, materials, power and fuel, royalties, payroll taxes, insurance, and general and 

administrative costs that are dependent upon the quantity of production and, thus, applicable as variable costs of 

production. Excluded from forward costs are prior expenditures, if any, incurred for property acquisition, exploration, mine 

development, and mill construction, as well as income taxes, profit, and the cost of money. Note: By use of forward costing, 

estimates of reserves for ore deposits in differing geological settings can be aggregated and reported as the maximum 

amount that can theoretically be extracted to recover the specified costs of uranium oxide production under the listed 

forward cost categories. 

Forward coverage: Amount of uranium required to assure uninterrupted operation of nuclear power plants. 

Fossil fuel: An energysource formed in the Earth's crust f I. The common fossil f Is are 

petroleum, coal, and natural gas. 

Fossil fuel plant: A plant using coal, petroleum, or gas as its source of energy. 

Fossil fuel steam-electric powerplant: An electricitygeneration plant in which the prime mover is a turbine rotated by highpressure steam produced in a boiler by heat from burning fossil f Is. 

Fossil-fuel electric generation: Electric generation in which the prime mover is a turbine rotated by high-pressure steam 

produced in a boiler by heat f I fuels. 

Foundry: An operation where metal castings are produced, using coke as a fuel. 

Foundry coke: This is a special coke that is used in furnaces to produce cast and ductile iron products. It is a source of 

heat and also helps maintain the required carbon content of the metal product. Foundry coke production requires lower 

temperatures and longer times than blast furnace coke. 

FPC: Federal Power Commission 

Fractionation: The process bywhich saturated hydrocarbons are removed from natural gas and separated into distinct 

products, or "fractions," such as propane, butane, and ethane. 

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F limate Change (FCCC): An agreement opened for signature at the "Earth Summit" in Rio de 

Janeiro, Brazil, on June 4, 1992, which has the goal of stabilizing greenhouse gas concentrations in the atmosphere at a 

level that would prevent significant anthropogenicallyforced climate change. 

F longside ship (f.a.s.): The value of a commodity at the port of exportation, generally including the purchase price plus 

all charges incurred in placing the commodity alongside the carrier at the port of exportation. 

Free on board (f.o.b.): Asales transaction in which the seller makes the product available for pick up at a specified port or 

terminal at a specified price and the buyer pays for the subsequent transportation and insurance. 

Free well: Awe!l drilled and equipped by an assignee as consideration for the assignment of a fractional share of the 

working interest, commonly under a farm-out agreement. 

Fresh feed input: Represents input of material (crude oil, unfinished oils, natural gas liquids, other hydrocarbons and 

oxygenates or finished products) to processing units at a refinery that is being processed (input) into a particular unit for the 

first time. 

Examples: 

(1) Unfinished oils coming out of a crude oil distillation unit which are input into a catalytic cracking unit are considered 

fresh feed to the catalytic cracking unit. 

(2) Unfinished oils coming out of a catalytic cracking unit being looped back into the same catalytic cracking unit to be 

reprocessed are not considered fresh feed. 

F feeds: Crude oil or petroleum distillates that are being fed to processing units for the first time. 

FRS: Financial Reporting System Survey (ElAsurvey). 

Fuel: Any material substance that can be consumed to supply heat or power. Included are petroleum, coal, and natural gas 

(the fossil f Is), and other consumable materials, such as uranium, biomass, and hydrogen. 

Fuel cell: A device capable of generating an electrical current by converting the chemical energy of a fuel (e.g., hydrogen) 

directly into electrical energy. Fuel cells differ from conventional electrical cells in that the active materials such as fuel and 

oxygen are not contained within the cell but are supplied from outside. It does not contain an intermediate heat cycle, as do 

most other electrical generation techniques. 

Fuel cycle: The entire set of sequential processes or stages involved in the utilization of fuel, including extraction, 

transformation, transportation, and combustion. Emissions generally occur at each stage of the fuel cycle. 

Fuel efficiency: SeeMiles per gallon. 

Fuel emergencies: An emergency that exists when supplies of fuels or hydroelectric storage for generation are at a level or 

estimated to be ata level that would threaten the reliability or adequacy of bulk electric power supply. The following factors 

should be taken into account to determine that a fuel emergency exists 1. Fuel stock or hydroelectric project water storage 

levels are 50 percent or less of normal for that particular time of the year and a continued downward trend in fuel stock or 

hydroelectric project water storage level is estimated; or 2. Unscheduled dispatch or emergency generation is causing an 

abnormal use of a particular fuel tfuture supply of stocks of that fuel could reach a level that threatens the 

reliability or adequacy of bulk electric power supply. 

Fuel ethanol: Ethanol intended for fuel use. Fuel ethanol in the United States must be anhydrous (less than 1 percent 

water). Fuel ethanol is denatured (made unfit for human consumption), usually prior to transport from the ethanol 

production facility, by adding 2 to 5 volume percent petroleum, ty Ily pentanes plus or conventional motor gasoline. Fuel 

ethanol is used principallyfor blending in low concentrations with motor gasoline as an oxygenate or octane enhancer. In 

high concentrations, it is used to fuel alternative-fuel vehicles specially designed for its use. SeeAlternative-Fuel Vehicle, 

Denaturant, E85, Ethanol, Fuel Ethanol Minus Denaturant, and Oxygenates. 

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Fuel Ethanol Minus Denaturant: An unobserved quantityof anhydrous, biomass-derived, undenatured ethanol for fuel use. 

The quantity is obtained by subtracting the estimated denaturant volume from fuel ethanol volume. Fuel ethanol minus 

denaturant is counted as renewable energy, while denaturant is counted as nonrenewable fuel. SeeDenaturant, Ethanol, 

Fuel Ethanol, Nonrenewable Fuels, and Oxygenates. 

Fuel expenses: These costs include the fuel used in the production of steam or driving another prime mover for the 

generation of electricity. Other associated expenses include unloading the shipped fuel and all handling of the fuel up to the 

point where it enters the first bunker, hopper, bucket, tank, or holder in the boiler-house structure. 

Fuel injection: A fuel delivery system whereby gasoline is pumped to one or more fuel injectors under high pressure. The 

fuel injectors are valves that, at the appropriate times, open to allow fuel to be sprayed or atomized into a throttle bore or into 

the intake manifold ports. The fuel injectors are usuallysolenoid operated valves under the control of the vehicle's on-board 

computer (thus the term "electronic fuel injection"). The fuel efficiency of fuel injection systems is less tern peraturedependent than carburetor systems. Diesel engines always use injectors. 

Fuel oil: A liquid petroleum product less volatile than gasoline, used as an energy source. Fuel oil includes distillate fuel oil 

(No. 1, No. 2, and No. 4), and residual fuel oil (No. 5 and No.6). 

Fuel oil supplier: SeeEnergy supplier. 

Fuel purchase agreement: An agreement between a company and a fuel provider which stipulates that the company 

agrees to purchase its fuel f I provider. If the company has a credit card for use at a fuel provider's locations, but 

is not bound by an additional agreement to purchase fuel f t provider, the credit card agreement alone is not 

considered a fuel purchase agreement. 

Fuel ratio: The ratio of fixed carbon to volatile matter in coal. 

Fuel switching capability: The short-term capability of a manufacturing establishment to have used substitute energy 

sources in place of those actually consumed. Capability to use substitute energy sources means that the establishment's 

combustors (for example, boilers, furnaces, ovens, and blast furnaces) had the machinery or equipment either in place or 

available for installation so that substitutions could actually have been introduced within 30 days without extensive 

modifications. Fuel-switching capability does not depend on the relative prices of energysources; it depends only on the 

characteristics of the equipment and certain legal constraints. 

Fuel wood: Wood and wood products, possibly including scrubs and branches, etc, bought or gathered, and used bydirect 

combustion. 

Fuel-switching DSM program assistance: DSM program assistance where the sponsor encourages consumers to 

change from one fuel to another for a particular end-use service. For example, utilities might encourage consumers to 

replace electric water heaters with gas units or encourage industrial consumers to use electric microwave heaters instead 

of natural gas-heaters. 

Fuelffabricator assembly identifier: Individual assembly identifier based on a numbering scheme developed by individual 

fI fabricators. Most f I fabricator assembly identifiers schemes closely match the scheme developed by the American 

National Standards Institute (ANSI) and are therefore unique. 

Fuels solvent deasphalting: A refining process for removing asphalt com pounds from petroleum fractions, such as 

reduced crude oil. The recovered stream from this process is used to produce fuel products. 

Fugitive emissions: Unintended leaks of gas from the processing, transmission, and/or transportation of fossil fuels. 

Full forced outage: The net capability of main generating units that are unavailable for load for emergency reasons. 

Full power day: The equivalent of 24 hours of full power operation by a reactor. The number of full power days in a specific 

cycle is the product of the reactor's capacityfactor and the length of the cycle. 

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Full power operation: Operation of a unit at 100 percent of its design capacity. Full-power operation precedes commercial 

operation. 

Full requirements consumer: Awholesale consumer without other generating resources whose electric energy seller is 

the sole source of long-term firm power for the consumer's service area. The terms and conditions of sale are equivalent to 

the seller's obligations to its own retail service, if any. 

Fumarole: Avent from which gas or steam issue; a geyser or spring that emits gases. 

Furnace: The part of a boiler or warm-air space-heating plant in which combustion takes place. 

Furnace coke plant: Acoke plant whose coke production is used primarily bythe producing company. 

Furnaces that heat directly, withoutusing steam or hot water (similar to a residential furnace): Furnaces burn natural 

gas, fuel oil, propane/ butane (bottled gas), or electricity to warm the air. The warmed air is then distributed throughout the 

building through ducts. Many people use the words "boilers" and "furnaces" interchangeably. They are not the same. We 

mean that warm air is produced directly by burning some fuel. Warm-air furnaces typically rely on air ducts to carrythe warm 

air throughout the building. Warm-air furnaces are often built in combination with central air-conditioning systems, so that 

they can use the same air ducts for either heating or air-conditioning (depending on the season). Other terms for describing 

this type of equipment include "central system," "split system," and "forced air/forces air furnace" 

Futures market: Atrade center for quoting prices on contracts for the delivery of a specified quantity of a commodity at a 

specified time and place in the future. 

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G 

GAAP: SeeGenerally Accepted Accounting Principles. 

gal: gallon 

Gallon: A volumetric measure equal to 4 quarts (231 cubic inches) used to measure fuel oil. One barrel equals 42 gallons. 

Gas: Anon-solid, non-liquid combustible energysource that includes natural gas, coke-oven gas, blast-furnace gas, and 

refinery gas. 

Gas Condensate Well Gas: Natural gas remaining after the removal of the lease condensate. 

Gas cooled fast breeder reactor (G FB): A fast breeder reactor that is cooled by a gas (usually helium) under pressure. 

Gas plant operator: Anyfirm, including a gas plant owner, which operates a gas plant and keeps the gas plant records. A 

gas plant is a facility in which natural gas liquids are separated from natural gas or in which natural gas liquids are 

fractionated or otherwise separated into natural gas liquid products or both. 

Gas processing unit: Afacilitydesigned to recover natural gas liquids from a stream of natural gas that mayor may not 

have passed through lease separators and/or field separation facilities. Another function of natural gas processing plants 

is to control the quality of the processed natural gas stream. Cycling plants are considered natural gas processing plants. 

Gas to liquids (GTL): A process that combines the carbon and hydrogen elements in natural gas molecules to make 

synthetic liquid petroleum products, such as diesel fuel. 

Gas turbine plant: A plant in which the prime mover is a gas turbine. A gas turbine consists typically of an mdal-flow air 

compressor and one or more combustion chambers where liquid or gaseous fuel is burned and the hot gases are passed 

to the turbine and where the hot gases expand drive the generator and are then used to run the com pressor. 

Gas well: Awell completed for production of natural gas from one or more gas zones or reservoirs. Such wells contain no 

completions for the production of crude oil. 

Gas well productivity: Derived annually by dividing gross natural gas withdrawals from gas wells by the number of 

producing gas wells on December 31 and then dividing the quotient by the number of days in the year. 

Gasification: A method for converting coal, petroleum, biomass, wastes, or other carbon-containing materials into a gas 

that can be burned to generate power or processed into chemicals and fuels. 

Gasohol: A blend of finished motor gasoline containing alcohol (generally ethanol but sometimes methanol) at a 

concentration between 5.7 percent and 10 percent by volume. Also seeOxygenates. 

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Gasoil: European and Asian designation for No. 2 heating oil and No. 2 diesel fuel. 

Gasoline: See Motor gasoline (f 

Gasoline blending components: Naphthas which will be used for blending or compounding into finished aviation or motor 

gasoline (e.g., straight-run gasoline, alkylate, reform ate, benzene, toluene, andxylene). Excludes oxygenates (alcohols, 

ethers), butane, and pentanes plus. 

Gasoline grades: The classification of gasoline by octane ratings. Each type of gasoline (conventional, oxygenated, and 

reformulated) is classified bythree grades - Regular, Midgrade, and Premium. Note: Gasoline sales are reported bygrade 

in accordance with their classification at the time of sale. In general, automotive octane requirements are lower at high 

altitudes. Therefore, in some areas of the United States, such as the Rocky Mountain States, the octane ratings for the 

gasoline grades maybe 2 or more octane points lower. 

• Regular gasoline: Gasoline having an antiknock index, i.e., octane rating, greater than or equal to 85 and less than 

88. Note Octane requirements may vary by altitude. 

• Midgrade gasoline: Gasoline having an antiknock index, i.e., octane rating, greater than or equal to 88 and less than 

or equal to 90. Note: Octane requirements m ay vary by altitude. 

• Premium gasoline: Gasoline having an antiknock index, i.e., octane rating, greater than 90. Note: Octane 

requirements may vary by altitudes or fluids at various depths beneath the surface of the earth. The energy is 

extracted by drilling and/or pumping. 

Gasoline motor, (leaded): Contains more than 0.05 grams of lead per gallon or more than 0.005 grams of phosphorus per 

gallon. The actual lead content of any given gallon may vary. Premium and regular grades are included, depending on the 

octane rating. Includes leaded gasohol. Blendstock is excluded until blending has been completed. Alcohol that is to be 

used in the blending of gasohol is also excluded. 

Gasoline treated as blendstock (GTAB): Non-certified Foreign Refinery gasoline classified by an importer as blendstock to 

be either blended or reclassified with respect to reformulated or conventional gasoline. GTAB is classified as either 

reformulated or conventional quality based on emissions performance, formulation, and intended end use. 

Gate station: Location where the pressure of natural gas being transferred from the transmission system to the distribution 

system is lowered for transport through small diameter, low pressure pipelines. 

Gatherer: A company primarily engaged in the gathering of natural gas from well or field lines for delivery, for a fee, to a 

natural gas processing plant or central point. Gathering companies may also provide compression, dehydration, and/or 

treating services. 

GDP: Gross Domestic Product 

Generally accepted accounting principles (GAAP): Defined bythe FASB as the conventions, rules, and procedures 

necessaryto define accepted accounting practice at a particular time, includes both broad guidelines and relatively detailed 

practices and procedures. 

Generating facility: An existing or planned location or site at which electricity is or will be produced. 

Generating station: A station that consists of electric generators and awdliary equipment for converting mechanical, 

chemical, or nuclear energy into electric energy. 

Generating unit: Any combination of physically connected generators, reactors, boilers, combustion turbines, and other 

prime movers operated together to produce electric power. 

Generation: The process of producing electric energy bytransforming other forms of energy; also, the amount of electric 

energy produced, expressed in kilowatthours. 

Generation company: An entity that owns or operates generating plants. The generation company may own the generation 

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plants or interact with the short-term market on behalf of plant owners. 

Generator capacity: The maximum output, commonly expressed in megawatts (M ), that generating equipment can 

supplyto system load, adjusted for ambient conditions. 

Generator nameplate capacity (installed): The maximum rated output of a generator, prime mover, or other electric power 

production equipment under specific conditions designated by the manufacturer. Installed generator nameplate capacity is 

commonly expressed in megawatts (MW) and is usually indicated on a nameplate physically attached to the generator. 

Geologic assurance: State of sureness, confidence, or certainty of the existence of a quantity of resources based on the 

distance from points where coal is measured or sampled and on the abundance and quality of geologic data as related to 

thickness of over burden, rank, quality, thickness of coal, areal extent, geologic history, structure, and correlations of coal 

beds and enclosing rocks. The degree of assurance increases as the nearness to points of control, abundance, and quality 

of geologic data increases. 

Geologic considerations: Conditions in the coal deposit or in the rocks in which it occurs that may complicate or preclude 

mining. Geologic considerations are evaluated in the context of the current state of technology and regulations, so the 

impact on mining may change with time. 

Geologic sequestration: A type of engineered sequestration, where captured carbon dioxide is injected for permanent 

storage into underground geologic reservoirs, such as oil and natural gas fields, saline aquifers, or abandoned coal mines. 

Geological and geophysical (G) costs: Costs incurred in making geological and geophysical studies, including, but not 

limited to, costs incurred for salaries, equipment, obtaining rights of access, and supplies for scouts, geologists, and 

geophysical crews. 

Geological repository: A mined facility for disposal of radioactive waste that uses waste packages and the natural geology 

as barriers to provide waste isolation. 

Geopressured: Atype of geothermal resource occurring in deep basins in which the fluid is under very high pressure. 

Geothermal energy: Hot water or steam extracted from geothermal reservoirs in the earth's crust. Water or steam extracted 

from geothermal reservoirs can be used for geothermal heat pumps, water heating, or electricity generation. 

Geothermal plant: A plant in which the prime mover is a steam turbine. The turbine is driven either by steam produced from 

hot water or by natural steam that derives its energyfrom heat found in rock. 

Geyser: Aspecial t I spring that periodically ejects water with great force. 

age: One billion 

Gigawaft (GW): One billion watts or one thousand megawatts. 

Gigawaft-electric (GWe): One billion watts of electric capacity. 

Gigawatthour (GWh): One billion watthours. 

Gilsonite: Trademark name for uintaite (or uintahite), a black, brilliantly lustrous natural variety of asphalt found in parts of 

Utah and western Colorado. 

Global climate change: See Climate change . 

Global warming: An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past 

as the result of natural influences, but the term is today most often used to refer to the warming some scientists predict will 

occur as a result of increased anthropogenic emissions of greenhouse gases. 

Global warming potential (GWP): An index used to compare the relative radiative forcing of different gases without directly 

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calculating the changes in atmospheric concentrations. GWPs are calculated as the ratio of the radiative forcing that would 

result from the emission of one kilogram of a greenhouse gas to that from the emission of one kilogram of carbon dioxide 

over a fixed period of time, such as 100 years. 

GNP: Gross National Product 

Government-owned stocks: Oil stocks owned by the national government and held for national security. In the United 

States, these stocks are known as the Strategic Petroleum Reserve. 

Green pricing: In the case of renewable electricity, green pricing represents a market solution to the various problems 

associated with regulatoryvaluation of the nonmarket benefits of renewables. Green pricing programs allow electricity 

customers to express their willingness to pay for renewable energy development through direct payments on their monthly 

utility bills. 

Greenhouse effect: The result of water vapor, carbon dioxide, and other atmospheric gases trapping radiant (infrared) 

energy, thereby keeping the earth's surface warmer than it would otherwise be. Greenhouse gases within the lower levels 

of the atmosphere trap this radiation, which would otherwise escape into space, and subsequent re-radiation of some of 

this energy back to the Earth maintains higher surface temperatures than would occur if the gases were absent. 

Greenhouse gases: Those gases, such as water vapor, carbon dioxide, nitrous oxide, methane, hydrofluorocarbons 

(HFCs), perfluorocarbons (PFCs) and sulf luoride, that are transparent to solar (short-wave) radiation but opaque to 

long-wave (infrared) radiation, thus preventing long-wave radiant energyfrom leaving Earth's atmosphere. The net effect is a 

trapping of absorbed radiation and a tendency to warm the planet's surface. 

Grid: The layout of an electrical distribution system. Seeelectric power grid. 

Gross additions to construction work in progress for the month: This amount should include the monthly gross 

additions for an electric plant in the process of construction. 

Gross company-operated production: Total production from all company-operated properties, including all working and 

nonworking interests. 

Gross domestic product (GDP): The total value of goods and services produced by labor and property located in the United 

States. As long as the labor and property are located in the United States, the supplier (that is, the workers and, for property, 

the owners) may be either U.S. residents or residents of foreign countries. 

Gross domestic product (GDP) implicit price deflator: The implicit price deflator, published by the U.S. Department of 

Commerce, Bureau of Economic Analysis, is used to convert nominal f I figures. 

Gross energy intensity: Total consumption of a particular energy source(s) or fuel(s) by a group of buildings, divided by the 

total floor space of those buildings, including buildings and floor space where the energy source or fuel is not used, i.e., the 

ratio of consumption to gross floor space. 

Gross gas withdrawal: The full-volume of compounds extracted at the wellhead, including nonhydrocarbon gases and 

natural gas plant liquids. 

Gross generation: The total amount of electric energy produced by generating units and measured at the generating 

terminal in kilowatthours (kWh) or megawatthours (M). 

Gross head: Adam's maximum allowed vertical distance between the upstream's surface water (headwater) forebay 

elevation and the downstream's surface water (tailwater) elevation at the tail-race for reaction wheel dams or the elevation 

of the jet at impulse wheel dams during specified operation and water conditions. 

Gross input to atmospheric crude oil distillation units: Total input to atmospheric crude oil distillation units. Includes all 

crude oil, lease condensate, natural gas plant liquids, unfinished oils, liquefied refinerygases, slop oils, and other liquid 

hydrocarbons produced from tar sands, gilsonite, and oil shale. 

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Gross inputs: The crude oil, unfinished oils, and natural gas plant liquids put into atmospheric crude oil distillation units. 

Gross national product (GNP): The total value of goods and services produced by the nation's economy before deduction of 

depreciation charges and other allowances for capital consumption. It includes the total purchases of goods and services 

by private consumers and government, gross private domestic capital investment, and net foreign trade. 

Gross vehicle weight rating (GVWR): Vehicle weight plus carrying capacity. 

Gross withdrawals: Full well stream volume from both oil and gas wells, including all natural gas plant liquids and 

nonhydrocarbon gases after oil, lease condensate, and water have been removed. Also includes production delivered as 

royalty payments and production used as fuel on the lease. 

Gross working interest ownership basis: Gross working interest ownership is the respondent's working interest in a 

given property plus the proportionate share of any royalt luding overriding royalty interest, associated with the 

working interest. 

Group: Agroup is a logical grouping of assemblies with similar characteristics. All assemblies in a group have the same 

initial average enrichment, the same cycle/reactor history, the same current location, the same burnup, the same owner, 

and the same assembly type. 

Group 3: A petroleum products spot market trading hub based in Tulsa, Oklahoma that serves the U.S. Mid-Continent 

region. 

soup name: The DOE/EIA-assigned name identifying a composite supply source (i.e., commonly metered gas streams 

from more than one field), which is often the case in contract areas, field areas, and plants. Agroup name can also be a 

pipeline purchase (i.e., FERC Gas Tariff, Canadian Gas, Mexican Gas, and Algerian LNG). Emergency purchases and short 

term purchases are also group names. Group Code - The DOE/EIA-assigned code identifying a composite supply source. 

Group quarters: Living arrangement for institutional groups containing ten or more unrelated persons. Group quarters are 

typicallyfound in hospitals, nursing or rest homes, military barracks, ships, halfway houses, college dormitories, fraternity 

and sorority houses, convents, monasteries, shelters, jails, and correctional institutions. Group quarters may also be found 

in houses or apartments shared by ten or more unrelated persons. Group quarters are often equipped with a dining area 

for residents. 

GVW: Gross Vehicle Weight 

GW: seeGigawatt 

Gwe: SeeGigawatt-electric. 

GWh: seeGigawatthour 

GWP: seeGlobal Warming Potential 

Gypsum: Calcium sulfate dihydrate (CaSO4 2H20) a sludge constituent f the conventional lime scrubber process, 

obtained as a byproduct of the dewatering operation and sold for commercial use. 

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H 

H: Hundred 

h: hundredth 

Half-life: The time it takes for an isotope to lose half of its radioactivity. 

Halogen lamp: A type of incandescent lamp that lasts much longer and is more efficient than the common incandescent 

lamp. The lamp uses a halogen gas, usually iodine or bromine, that causes the evaporating tungsten to be redeposited on 

the filament, thus prolonging its life. Also seeIncandescent lamp. 

Halogenated substances: A volatile compound containing halogens, such as chlorine, fluorine or bromine. 

Hand loading: An underground loading method bywhich coal is removed from the working face by manual labor through 

the use of a shovel for conveyance to the surface. Though rapidly disappearing, it is still used in small-tonnage mines. 

Haulage cost: Cost of loading ore at a mine site and transporting it to a processing plant. 

HCFC: SeeHydrochlorofluorocarbon 

HDD: SeeHeating Degree-days 

Head: The product of the water's weight and a usable difference in elevation gives a measurement of the potential energy 

possessed by water. 

Heap leach solutions: The separation, or dissolv -out from mined rock of the soluble uranium constituents by the natural 

action of percolating a prepared chemical solution through mounded (heaped) rock material. The mounded material 

usually contain slow grade mineralized material and/or waste rock produced from open pit or underground mines. The 

solutions are collected after percolation is completed and processed to recover the valued components. 

Heat content: The amount of heat energy available to be released by the transformation or use of a specified physical unit 

of an energy form (e.g., a ton of coal, a barrel of oil, a kilowatthour of electricity, a cubic foot of natural gas, or a pound of 

steam). The amount of heat energy is commonly expressed in British thermal units (Btu). Note: Heat content of combustible 

energy forms can be expressed in terms of either gross heat content (higher or upper heating value) or net heat content 

(lower heating value), depending upon whether or not the available heat energy includes or excludes the energy used to 

vaporize water (contained in the original energy form or created during the combustion process). The Energy Information 

Administration typically uses gross heat content values. 

Heat pump: Heating and/or cooling equipment that, during the heating season, draws heat into a building from outside 

and, during the cooling season, ejects heat f the building to the outside. Heat pumps are vapor-compression 

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refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the 

need for heating or cooling. 

Heat pump (air source): An air-source heat pump is the most common type of heat pump. The heat pump absorbs heat 

f the outside air and transfers the heat to the space to be heated in the heating mode. In the cooling mode the heat 

pump absorbs heat f the space to be cooled and rejects the heat to the outside air. In the heating mode when the 

outside air approaches 32o F or less, air-source heat pumps loose efficiency and generally require a back-up (resistance) 

heating system. 

Heat pump (geothermal): A heat pump in which the refrigerant exchanges heat (in a heat exchanger) with a fluid circulating 

through an earth connection medium (ground or ground water). The fluid is contained in a variety of loop (pipe) 

configurations depending on the temperature of the ground and the ground area available. Loops may be installed 

horizontally or vertically in the ground or submersed in a body of water. 

Heat pump efficiency: The efficiency of a heat pump, that is, the electrical energy to operate it, is directly related to 

temperatures between which it operates. Geothermal heat pumps are more efficient than conventional heat pumps or air 

conditioners that use the outdoor air since the ground or ground water a few feet below the earth's surface remains 

relatively constant throughout the year. It is more efficient in the winter to draw heat from the relatively warm ground than 

from the atmosphere where the air temperature is much colder, and in summer transfer waste heat to the relatively cool 

ground than to hotter air. Geothermal heat pumps are generally more expensive ($2,000-$5,000) to install than outside air 

heat pumps. However, depending on the location geothermal heat pumps can reduce energy consumption (operating cost) 

and correspondingly, emissions by more than 20 percent compared to high-efficiency outside air heat pumps. Geothermal 

heat pumps also use the waste heat from air-conditioning to provide free hot water heating in the summer. 

Heat rate: A measure of generating station thermal eff ly stated as Btu per kilowatthour. Note: Heat rates 

can be expressed as either gross or net heat rates, depending whether the electricity output is gross ornet generation. 

Heat rates are typically expressed as net heat rates. 

Heated floorspace: The area within a building that is space heated. 

Heating Degree-Days (HDD): A m easure of how cold a location is over a period of time relative to a base temperature, most 

commonly specified as 65 degrees Fahrenheit. The measure is computed for each day by subtracting the average of the 

days high and low temperatures from the base temperature (65 degrees), with negative values set equal to zero. Each 

days heating degree-days are summed to create a heating degree-day measure for a specified reference period. Heating 

degree-days are used in energy analysis as an indicator of space heating energy requirements or use. 

Heating equipment: Any equipment designed and/or specifically used for heating ambient air in an enclosed space. 

Common types of heating equipment include: central warm air furnace, heat pump, plug-in or built-in room heater, boiler for 

steam or hot water heating system, heating stove, and fireplace. Note: A cooking stove in a housing unit is sometimes 

reported as heating equipment, even though it was built for preparing food. 

Heating intensity: The ratio of space-heating consumption or expenditures to square footage of heated floor space and 

heating degree-days (base 65 degrees Fahrenheit). This ratio provides a way of comparing different ty f housing units 

and households by controlling for differences in housing unit size and weather conditions. The square footage of heated 

floor space is based on the measurements of the floor space that is heated. The ratio is calculated on a weighted, 

aggregate basis according to the following formula Heating Intensity =Btu for Space Heating / (Heated Square Feet* 

Heating Degree-Days). 

Heating stove burning wood, coal, or coke: Any free-standing box or controlled-draft stove; or a stove installed in a 

fireplace opening, using the chimney of the fireplace. Stoves are made of cast iron, sheet metal, or plate steel. Freestanding fireplaces that can be detached from their chimneys are considered heating stoves. 

Heating value: The average number of British thermal units per cubic foot of natural gas as determined from tests off I 

samples. 

Heavy gas oil: Petroleum distillates with an approximate boiling range from 651 degrees Fahrenheit to 1000 degrees 

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Fahrenheit. 

Heavy metals: Metallic elements, including those required for plant and animal nutrition, in trace concentration but which 

become toxic at higher concentrations. Examples are mercury, chromium, cadmium, and lead. 

Heavy rail: An electric railway with the capacity for a "heavy volume" of traffic and characterized by exclusive rights-of-way, 

multi-car trains, high speed and rapid acceleration, sophisticated signaling, and high platform loading. Also known as 

"subway," elevated (railway), "metropolitan railway (metro)." 

Heavy water: Water containing a significantly greater proportion of heavy hydrogen (deuterium) atoms to ordinary hydrogen 

atoms than is found in ordinary (light) water. Heavy water is used as a moderator in some reactors because it slows 

neutrons effectively and also has a low cross section for absorption of neutrons. 

Heavy-water-moderated reactor: A reactor that uses heavy water as its moderator. Heavywater is an excellent moderator 

and thus permits the use of in expensive natural (unenriched) uranium as fuel. 

Hedging: The buying and selling of futures contracts so as to protect energytraders from unexpected or adverse price 

fluctuations. 

Hedging contracts: Contracts which establish future prices and quantities of electricity independent of the short-term 

market. Derivatives may be used for this purpose. 

Heliostat: A m irror that reflects solar rays onto a central receiver. A heliostat automatically adjusts its position to track daily 

or seasonal changes in the sun's position. The arrangement of heliostats around a central receiver is also called a solar 

collector field. 

Henry Hub: A pipeline hub on the Louisiana Gulf coast. It is the delivery point for the natural gas futures contract on the New 

York Mercantile Exchange (NYMEX). 

HFC: See Hydrofluorocarbon 

HID: High-Intensity Discharge 

High efficiency ballast: Alighting conservation feature consisting of an energy-efficient version of a conventional 

electromagnetic ballast. The ballast is the transformer for fluorescent and high-intensity discharge (HID) lamps, which 

provides the necessary current, voltage, and wave-form conditions to operate the lamp. A high-efficiency ballast requires 

lower power input than a conventional ballast to operate HID and fluorescent lamps. 

High efficiency lighting: Lighting provided by high-intensity discharge (HID) lamps and/or fluorescent lamps. 

High-intensity discharge (HID) lamp: A lamp that produces light by passing electricity through gas, which causes the gas to 

glow. Examples of HID lamps are mercuryvapor lamps, metal halide lamps, and high-pressure sodium lamps. HID lamps 

have extremely long life and emit far more lumens per fixture than do fluorescent lights. 

High-mileage households: Households with estimated aggregate annual vehicle mileage that exceeds 12,500 miles. 

High-temperature collector: A solar thermal collector designed to operate at a tern perature of 180 degrees Fahrenheit or 

higher. 

Highwall: The unexcavated face of exposed over-burden and coal in a surface mine. 

Hinshaw pipeline: A pipeline or local distribution company that has received exemptions from regulations pursuant to the 

Natural Gas Act. These companies transport interstate natural gas not subject to regulations under NGA 

Holding company: A com pany that confines its activities to owning stock in and supervising management of other 

companies. The Securities and Exchange Commission, as administrator of the Public Utility Holding CompanyAct of 1935, 

defines a holding company as "a companywhich directly or indirectly owns, controls or holds 10 percent or more of the 

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outstanding voting securities of a holding company' (15 USC 79b, par. a (7)). 

Holding pond: A structure built to contain large volumes of liquid waste to ensure that it meets environmental requirements 

prior to release. 

Horizontal axis wind turbine: The most common type of wind turbine where the a)ds of rotation is oriented horizontally. Also 

seeWind turbine. 

Horsepower: A unit for measuring the rate of work (or power) equivalent to 33,000 foot-pounds per minute or 746 watts. 

Host government: The government (including any government-controlled firm engaged in the production, refining, or 

marketing of crude oil or petroleum products) of the foreign countr the crude oil is produced. 

Hot dry rock: Heat energy residing in impermeable, crystalline rock. Hydraulic fracturing may be used to create 

permeability to enable circulation of water and removal of the heat. 

Hot tub: Water-f Iled wood, plastic, or ceramic container in which up to 12 people can lounge. Normally equipped with a 

heater that heats the water from 80 degrees to 106 degrees Fahrenheit. It may also have jets to bubble the water. The water 

is not drained after each use. An average-size hot tub holds 200 to 400 gallons of water. All reported hot tubs are assumed 

to include an electric pump. These are also called spas or jacuzzis. 

Hours under load: The hours the boiler is operating to drive the generator producing electricity. 

Household: A fam ily I, or a group of up to nine unrelated persons occupying the same housing unit. "Occupy' 

means that the housing unit is the person's usual or permanent place of residence. 

Household energy expenditures: The total amount of funds spent for energy consumed in, or delivered to, a housing unit 

during a given period of time. 

Housing unit: A house, an apartment, a group of rooms, or a single room if it is either occupied or intended for occupancy 

as separate living quarters by a family, an individual, or a group of one to nine unrelated persons. Separate living quarters 

means the occupants (1) live and eat separately from other persons in the house or apartment and (2) have direct access 

from the outside of the buildings or through a common hall--that is, they can get to it without going through someone else's 

living quarters. Housing units do not include group quarters such as prisons or nursing homes where ten or more 

unrelated persons live. A common dining area used by residents is an indication of group quarters. Hotel and motel rooms 

are considered housing units if occupied as the usual or permanent place of residence. 

HTGR: High Temperature Gas-cooled Reactor 

Hub height: In a horizontal-axis wind turbine, the distance from the turbine platform to the rotor shaft. 

Humidifier: A humidifier adds moisture to the air(often needed in winter when indoor air is very dry). It maybe a portable 

unit or attached to the heating system. 

Humidity: The moisture content of air. Relative humidity is the ratio of the amount of water vapor actually present in the air to 

the greatest amount possible at the same temperature. 

HVAC: An abbreviation for the heating, ventilation, and air-conditioning system; the system or systems that condition air in a 

building. 

HVAC conservation feature: A building feature designed to reduce the amount of energy consumed by the heating, 

cooling, and ventilating equipment. 

HVAC DSM program: A DSM (demand-side management)program designed to promote the efficiency of the heating or 

cooling deliverysystem, including replacement. Includes ventilation (economizers; heat recoveryfrom exhaust air), cooling 

(evaporative cooling, cool storage; heat recovery from chillers; high-efficiency air conditioning), heating, and automatic 

energy management systems. 

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Hybrid transmission line: A double-circuit line that has one alternating current and one direct circuit. The AC circuit usually 

serves local loads along the line. 

Hydraulic fracturing: Fracturing of rock at depth with fluid pressure. Hydraulic fracturing at depth maybe accomplished by 

pumping water into a well at very high pressures. Under natural conditions, vapor pressure may rise high enough to cause 

fracturing in a process known as hydrothermal brecciation. 

Hydraulic head: The distance between the respective elevations of the upstream water surface (headwater) above and the 

downstream surface water (tailwater) below a hydroelectric power plant. 

Hydrocarbon: An organic chemical compound of hydrogen and carbon in the gaseous, liquid, or solid phase. The 

molecular structure of hydrocarbon compounds varies from the simplest (methane, a constituent of natural gas) to the very 

heavy and very coni plex. 

Hydrochlorofluorocarbons (HCFCs): Chemicals composed of one or more carbon atoms and varying numbers of 

hydrogen, chlorine, and fluorine atoms. 

Hydrocracking: SeeCatalytic hydrocracking. 

Hydroelectric power: The use of flowing water to produce electrical energy. 

Hydrofluorocarbons (HFCs): A group of man-made chemicals composed of one or two carbon atoms and varying numbers 

of hydrogen and fluorine atoms. Most HFCs have 100-year Global Warming Potentials in the thousands. 

Hydrogen: The lightest of all gases, occurring chiefly in combination with oxygen in water; exists also in acids, bases, 

alcohols, petroleum, and other hydrocarbons. 

Hydrotreating: SeeCatalytic hydrotreating. 

Hydroxyl radical (OH): An important chemical scavenger of many trace gases in the atmosphere that are greenhouse 

gases. Atmospheric concentrations of OH affect the atmospheric lifetimes of greenhouse gases, their abundance, and, 

ultimately, the effect they have on climate. 

Hypothetical resources (coal): Undiscovered coal resources in beds that may reasonably be expected to exist in known 

mining districts under known geologic conditions. In general, hypothetical resources are in broad areas of coal f Ids where 

points of observation are absent and evidence is from distant outcrops, drill holes, or wells. Exploration that confirms their 

existence and better defines their quantity and quality would permit their reclassification as identified resources. 

Quantitative estimates are based on a broad knowledge of the geologic character of coalbed or region. Measurements of 

coal thickness are more than 6 miles apart. The assumption of continuity of coalbed is supported only by geologic 

evidence. 

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Identified resources: Coal deposits whose location, rank, quality, and quantity are known from geologic evidence 

supported by engineering measurements. Included are beds of bituminous coal and anthracite (14 or more inches thick) 

and beds of subbituminous coal and lignite (30 or more inches thick) that occur at depths to 6,000 feet. The existence and 

quantity of these beds have been delineated within specified degrees of geologic assurance as measured, indicated, or 

inferred. Also included are thinner and/or deeper beds that presently are being mined or for which there is evidence that 

they could be mined commercially. 

Idle capacity: The component of operable capacity that is not in operation and not under active repair, but capable of being 

placed in operation within 30 days; and capacity not in operation but under active repair that can be completed within 90 

days. 

!EA: International Energy Agency 

Impedance: The opposition to power flow in an AC circuit. Also, any device that introduces such opposition in the form of 

resistance, reactance, or both. The impedance of a circuit or device is measured as the ratio of voltage to current, where a 

sinusoidal voltage and current of the same frequencyare used for the measurement; it is measured in ohms. 

Implicit price deflator: The implicit price deflator, published bythe U.S. Department of Commerce, Bureau of Economic 

Analysis, is used to convert nominal figures to real figures. 

Implied heat rate: A calculation of the day-ahead electric price divided by the day-ahead natural gas price. Implied heat rate 

is also known as the 'break-even natural gas market heat rate,' because only a natural gas generator with an operating 

heat rate (measure of unit efficiency) below the implied heat rate value can make money by burning natural gas to generate 

power. Natural gas plants with a higher operating heat rate cannot make money at the prevailing electricity and natural gas 

prices. 

Imported crude oil burned as fuel: The amount of foreign crude oil burned as a fuel oil, usually as residual f I oil, without 

being processed as such. Imported crude oil burned as fuel includes lease condensate and liquid hydrocarbons produced 

from tarsands, gilsonite, and oil shale. 

Imported Refiners' Acquisition Cost (IRAC): The average price for imported oil paid by U.S. refiners. 

Imports: Receipts of goods into the 50 States and the District of Columbia from U.S. possessions and territories or from 

foreign countries. 

Improved recovery: Extraction of crude oil or natural gas by any method other than those that rely primarily on natural 

reservoir pressure, gas lift, or a system of pumps. 

In situ leach mining (ISL): The recovery, by chemical leaching, of the valuable components of a mineral deposit without 

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physical extraction of the mineralized rock from the ground. Also referred to as "solution mining." 

In-house Demand-Side Management (DSM) program sponsor: The building's owner or management encourages 

consumers in the building to improve energy efficiency, reduce energycosts, change timing or energy usage, or promote 

the use of a different energy source by sponsoring its own DSM programs. 

In-use (vehicles): Implies that a vehicle is: 

1. Registered with the Government of one or more States, the District of Columbia, the Commonwealth of Puerto Rico, 

or the Virgin Islands; or 

2. The vehicle is owned or operated bya Government or military organization within the United States that is not 

required to register vehicles with the Government agencies listed under 1 above. For example, civilian Federal 

vehicles are generally not required to register with the State Government in which they are assigned. 

Inadvertent power exchange: An unintended power exchange among utilities that is either not previously agreed upon or 

in an amount different from the amount agreed upon. 

Incandescent lamp: A glass enclosure in which light is produced when a tungsten filament is electrically heated so that it 

glows. Much of the energy is converted into heat; therefore, this class of lamp is a relatively inefficient source of light. 

Included in this categoryare the familiar screw-in light bulbs, as well as somewhat more efficient lamps, such as tungsten 

halogen lamps, reflector or r-lam ps, parabolic aluminized reflector (PAR) lamps, and ellipsoidal reflector(ER) lamps. 

Incandescent light bulbs, including regular or energy-efficient light bulbs: An incandescent bulb is a type of electric light 

in which light is produced bya filament heated by electric current. The most common example is the type you find in most 

table and floor lamps. In commercial buildings, incandescent lights are used for display lights in retail stores, hotels and 

motels. This includes the verysmall, high-intensitytrack lights used to display merchandise or provide spot illumination in 

restaurants. Energy efficient light bulbs, known as "watt-savers," use less energy than a standard incandescent bulb. 

"Long-life" bulbs, bulbs that last longer than standard incandescent but produce considerably less light, are not considered 

energy-efficient bulbs. This category also includes halogen lamps. Halogen lamps are a special type of incandescent lamp 

containing halogen gas to produce a brighter, whiter light than standard incandescent. Halogen lamps come in three styles 

bulbs, models with reflectors, and infrared models with reflectors. Halogen lamps are especially suited to recessed or 

"canned fixtures," track lights, and outdoor lights. 

Incentives Demand-Side Management (DSM) program assistance: This DSM program assistance offers monetaryor 

non-monetary awards to encourage consumers to buy energy-efficient equipment and to participate in programs designed 

to reduce energy usage. Examples of incentives are zero or low-interest loans, rebates, and direct installation of low cost 

measures, such as water heater wraps or ductwork for distributing the cool air; the units condition air only in the room or 

areas where they are located. 

Incremental effects: The annual changes in energy use (measured in megawatt hours) and peak load (measured in 

kilowatts) caused by new participants in existing DSM (Demand-Side Management) programs and all participants in new 

DSM programs during a given year. Reported Incremental Effects are annualized to indicate the program effects that would 

have occurred had these participants been initiated into the program on January 1 of the given year. Incremental effects are 

not simply the Annual Effects of a given year minus the Annual Effects of the prior year, since these net effects would fail to 

account for program attrition, equipment degradation, building demolition, and participant dropouts. Please note that 

Incremental Effects are not a monthly disaggregate of the Annual Effects, but are the total year's effects of onlythe new 

participants and programs for that year. 

Incremental energy costs: The additional cost of producing and/or transmitting electric energy above some previously 

determined base cost. 

Independent power producer: A corporation, person, agency, authority, or other legal entity or instrumentality that owns or 

operates facilities for the generation of electricity for use primarily by the public, and that is not an electric utility. 

Independent system operator (ISO): An independent, federally regulated entity established to coordinate regional 

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transmission in a non-discriminatory manner and ensure the safetyand reliabilityof the electric system. FERC definition 

Indian coal lease: A lease granted to a mining company to produce coal f Indian lands in exchange for royalties and 

other revenues; obtained by direct negotiation with Indian tribal authorities, but subject to approval and administration by the 

U.S. Department of the Interior. 

Indicated reserves: SeeProbable energy reserves. 

Indicated resources, coal: Coal for which estimates of the rank, quality, and quantity are based partly on sample analyses 

and measurements and partlyon reasonable geologic projections. Indicated resources are computed partlyfrom specified 

measurements and partlyfrom projection of visible data for a reasonable distance on the basis of geologic evidence. The 

points of observation are 1/2 to 1-1/2m iles apart. Indicated coal is projected to extend as a 1/2-m ile-widebelt that lies more 

than 1/4 mile from the outcrop, points of observation, or measurement. 

Indirect cost: Costs not directly related to mining or milling operations, such as overhead, insurance, security, office 

expenses, property taxes, and similar administrative expenses. 

Indirect uses (end-use category): The end-use categorythat handles boiler fuel. Fuel in boilers is transformed into 

another useful energy source, steam or hot water, which is in turn used in other end uses, such as process or space 

heating or electricitygeneration. Manufacturers find measuring quantities of steam as it passes through to various end 

uses especially difficult because variations in both temperature and pressure affect energy content. Thus, the MECS (an EIA 

survey) does not present end-use estimates of steam or hot water and shows onlythe amount of the fuel used in the boiler 

to produce those secondary energy sources. 

Indirect utility cost: A utility cost that may not be meaning fully identified with any particular DSM program category. Indirect 

costs could be attributable to one of several accounting cost categories (i.e., Administrative, Marketing, Monitoring 

evaluation, Utility-Earned Incentives, Other). Accounting costs that are known DSM program costs should not be reported 

under Indirect Utility Cost; those costs should be reported as Direct Utility Costs under the appropriate DSM program 

category. 

Industrial production: The Federal Reserve Board calculates this index by compiling indices of physical output from a 

variety of agencies and trade groups, weighting each index by the Census' value added, and adding it to the cost of 

materials. When physical measures are not available, the Federal Reserve Board uses the number of production workers 

or amount of electricity consumed as the basis for the index To convert industrial production into dollars, multiply bythe 

"real value added" estimate used bythe Federal Reserve Board. 

Industrial restrictions (coal): Land-use restrictions that constrain, postpone, or prohibit mining in order to meet other 

industrial needs or goals; for example, resources not mined due to safety concerns or due to industrial or societal priorities, 

such as to preserve oil or gas wells that penetrate the coal reserves; to protect surface features such as pipelines, power 

lines, or corn panyfacilities; or to preserve public or private assets, such as highways, railroads, parks, or buildings. 

Industrial sector: An energy-consuming sector that consists of all facilities and equipment used for producing, processing, 

or assembling goods. The industrial sector encompasses the following types of activity manufacturing (NAICS codes 31-

33); agriculture, forestry, fishing and hunting (NAICS code 11); mining, including oil and gas extraction (NAICS code 21); and 

construction (NAICS code 23). Overall energy use in this sector is largelyfor process heat and cooling and powering 

machinery, with lesser amounts used for facility heating, air conditioning, and lighting. Fossil fuels are also used as raw 

material inputs to manufactured products. Note: This sector includes generators that produce electricity and/or useful 

thermal output primarily to support the above-mentioned industrial activities. Various EIA programs differ in sectoral 

coverage-for more information seeAdditional Information for Industrial Sector. 

Inferred reserve base (coal): the resources in the inferred reliability category that meet the same criteria of bed thickness 

and depth from surface as the demonstrated reserve base. 

Inferred resources: Coal in unexplored extensions of demonstrated resources for which estimates of the quality and size 

are based on geologic evidence and projection. Quantitative estimates are based largelyon broad knowledge of the 

geologic character of the bed or region and where few measurements of bed thickness are available. The estimates are 

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based primarily on an assumed continuation from demonstrated coal for which there is geologic evidence. The points of 

observation are 1-1/2 to 6 miles apart. Inferred coal is projected to extend as a 2-1/4-mile wide belt that lies more than 3/4 

mile from the outcrop, points of observation, or measurement. 

Initial enrichment: Average enrichment for a fresh fuel assembly as specified and ordered in fuel cycle planning. This 

average should include axial blankets and axiallyand radiallyzoned enrichments. 

Initial operation: First availability of a newly constructed unit to provide power to the grid. For a nuclear unit, this time is 

when the Full Power Operating License for the unit is received. 

In tural gas injected into storage reservoirs. 

Inoperable capacity: Generating capacity that is totally or partially out of service at the time of system peak load, either for 

scheduled outages (see GADS definition of "scheduled outages." These include both maintenance outages and planned 

outages.) or for reasons such as environmental restrictions; extensive modifications or repair; or capacity specified as 

being in a mothballed state. This does not include derated portions of generating capacity. 

Installed nameplate capacity: See Generator nameplate capacity (installed). 

Instantaneous peak demand: The maximum demand at the instant of greatest load. 

Instantaneous water heater: Also called a "tankless" or "point-of-use" water heater. The water is heated at the point of use 

as it is needed. 

Institutional living quarters: Space provided by a business or organization for long-term housing of individuals whose 

reason for shared residence is their association with the business or organization. Such quarters commonly have both 

individual and group living spaces, and the business or organization is responsible for some aspects of resident life 

beyond the simple provision of living quarters. Examples include prisons; nursing homes and other long-term medical care 

facilities; military barracks; college dormitories; and convents and monasteries. 

Insulation: Any material or substance that provides a high resistance to the flow of heat f to another. The 

different types include blanket or batt, foam, or loose fill, which are used to reduce heat transfer by conduction. Dead air 

space is an insulating medium in storm windows and storms as it reduces passage of heat through conduction and 

convection. Reflective materials are used to reduce heat transfer by radiation. 

Insulation around heating and/or cooling ducts: Extra insulation around the heating and/or cooling ducts intended to 

reduce the loss of hot or cold air as it travels to different parts of the residence. 

Insulation around hot-water pipes: Wrapping of insulating material around hot-water pipes to reduce the loss of heat 

through the pipes. 

Insulation around water heater: Blanket insulation wrapped around the water heater to reduce loss of heat. To qualify 

under this definition, this wrapping must be in addition to any insulation provided bythe manufacturer. 

Insulator: A material that is a very poor conductor of electricity. The insulating material is usually a ceramic or fiberglass 

when used in the transmission line and is designed to supporta conductor physically and to separate it electricallyfrom 

other conductors and supporting material. 

Intangible drilling and development costs (IDC): Costs incurred in preparing well locations, drilling and deepening wells, 

and preparing wells for initial production up through the point of installing control valves. None of these functions, because 

of their nature, have salvage value. Such costs would include labor, transportation, consumable supplies, drilling tool 

rentals, site clearance, and similar costs. 

Integral collector storage (ICS): Asolar thermal collector in which incident solar radiation is absorbed directly by the 

storage medium. 

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Integrated demand: The summation of the continuouslyvarying instantaneous demand averaged over a specified interval 

of time. The information is usually determined by examining a demand meter. 

Integrated gasification-combined cycle technology: Coal, water, and oxygen are fed to gasifier, which produces syngas. 

This medium-Btu gas is cleaned (particulates and sulf ) and is fed to a gas turbine. The hot exhaust 

of the gas turbine and heat recovered from the gasification process are routed through a heat-recovery routed through a 

heat-recovery generator to produce steam, which drives a steam turbine to produce electricity. 

Intensity: The amount of a quantity per unit floor space. This method adjusts either the amount of energy consumed or 

expenditures spent, for the effects of various building characteristics, such as size of the building, number of workers, or 

number of operating hours, to facilitate comparisons of energy across time, fuels, and buildings. 

Intensity per hour: Total consumption of a particular fuel(s) divided by the total floor space of buildings that use the fuel(s) 

divided bytotal annual hours of operation. 

Interchange (electric): Energy transfers that cross Balancing Authority boundaries. NERC definition 

Interchange authority (electric): The responsible entity that authorizes implementation of valid and balanced Interchange 

Schedules between Balancing Authority Areas, and ensures communication of Interchange information for reliability 

assessment purposes. NERC definition 

Interchange energy: Kilowatthours delivered to or received by one electric utility or pooling system from another. Settlement 

may be payment, returned in kind at a later time, or accumulated as energy balances until the end of the stated period. 

Interchange transaction (electric): An agreement to transfer energy from a seller to a buyer that crosses one or more 

Balancing AuthorityArea boundaries. NERC definition 

Intercity bus: A bus designed for high speed, long distance travel; equipped with front doors only, high backed seats, and 

usually restroom facilities. 

Interconnected system: Asystem consisting of two or more individual power systems normally operating with connecting 

tie lines. 

Interconnection: Two or more electric systems having a common transmission line that permits a flow of energy between 

them. The physical connection of the electric power transmission facilities allows for the sale or exchange of energy. 

Interdepartmental sales: Includes amounts charged bythe electric department at tariff or other specified rates for electricity 

supplied by it to other utility departments. 

Interdepartmental service (electric): Interdepartmental service includes amounts charged bythe electric department at 

tariff or other specified rates for electricity supplied by it to other utility departments. 

Interest coverage ratio: The number of times that fixed interest charges were earned. It indicates the margin of safetyof 

interest on fixed debt. The times-interest-earned ratio is calculated using net income before and after income taxes; and the 

credits of interest charged to construction being treated as other income. The interest charges include interest on long-term 

debt, interest on debt of associated companies, and other interest expenses. 

Intergovernmental Panel on Climate Change (IPCC): A panel established jointly in 1988 by the World Meteorological 

Organization and the United Nations Environment Program to assess the scientific information relating to climate change 

and to formulate realistic response strategies. 

Interlocking directorates: The holding of a significant position in management or a position on the corporate board of a 

utilitywhile simultaneously holding a comparable position with another utility th a firm doing business with the utility. 

Intermediate grade gasoline: A grade of unleaded gasoline with an octane rating intermediate between "regular" and 

"premium." Octane boosters are added to gasolines to control engine pre-ignition or "knocking" by slowing combustion 

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rates. 

Intermediate load (electric system): The range from base load to a point between base load and peak. This point maybe 

the midpoint, a percent of the peak load, or the load over a specified time period. 

Intermittent electric generator or intermittent resource: An electric generating plant with output controlled by the natural 

variability of the energy resource rather than dispatched based on system requirements. Intermittent output usually results 

from the direct, non-stored conversion of naturally occurring energyfluxes such as solar energy, wind energy, or the energy 

of free-flowing rivers (that is, run-of-river hydroelectricity). 

Internal Collector Storage (ICS): Asolar thermal collector in which incident solar radiation is absorbed by the storage 

medium. 

Internal combustion plant: A plant in which the prime mover is an internal combustion engine. An internal combustion 

engine has one or more cylinders in which the process of combustion takes place, converting energy released from the 

rapid burning of a fuel-air mixture into mechanical energy. Diesel or gas-fired engines are the principal t 

lectric plants. The plant is usually operated during periods of high demand for electricity. 

International bunker fuels: SeeBunker fuels. 

Interruptible gas: Gas sold to customers with a provision that permits curtailment or cessation of service at the discretion 

of the distributing company under certain circumstances, as specified in the service contract. 

Interruptible load: This Demand-Side Management category represents the consumer load that, in accordance with 

contractual arrangements, can be interrupted at the time of annual peak load by the action of the consumer at the direct 

request of the system operator. This type of control usually involves large-volume commercial and industrial consumers. 

Interruptible Load does not include Direct Load Control. 

Interruptible load or interruptible demand (electric): Demand that the end-use customer makes available to its LoadServing Entity via contract or agreement for curtailmentNERC definition 

Interruptible or curtailable rate: Aspecial electricity or natural gas arrangement under which, in return for lower rates, the 

customer must either reduce energy demand on short notice or allow the electric or natural gas utility to tern porarily cut off 

the energysupplyfor the utilityto maintain service for higher priority users. This interruption or reduction in demand typically 

occurs during periods of high demand for the energy (summer for electricity and winter for natural gas). 

Interruptible power: Power and usuallythe associated energy made available by one utilityto another. This transaction is 

subject to curtailment or cessation of delivery bythe supplier in accordance with a prior agreement with the other partyor 

under specified conditions. 

Interstate companies: Natural gas pipeline companies subject to Federal Energy Regulatory Commission (FERC) 

jurisdiction. 

Interstate pipeline: Any person engaged in natural gas transportation subject to the jurisdiction of Federal Energy 

Regulatory Commission (FERC) under the Natural Gas Act. 

Interstate pipeline purchase: Any gas supply contracted from and volumes purchased from other interstate pipelines, 

overland natural gas import purchases, and LNG, SNG, or coal gas purchases from domestic or foreign sources. 

Purchases from intrastate pipelines to section 311 (b) of the NGPA of 1978 and from independent producers are not 

included with interstate pipelines purchase. 

Intransit deliveries: Redeliveries to a foreign country of foreign gas received for transportation across U.S. territory, and 

deliveries of U.S. gas to a foreign countryfor transportation across its territory and redelivery to the United States. 

Intransit receipts: Receipts of foreign gas for transportation across U.S. territory and redelivery to a foreign country, and 

redeliveries to the United States of U.S. gas transported across foreign territory. 

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Intrastate companies: Companies not subject to Federal Energy Regulatory Commission (FERC) jurisdiction. 

Intrastate pipeline: Any person engaged in natural gas transportation (not including gathering) that is not subject to the 

jurisdiction of the Commission under the Natural Gas Act (other than anysuch pipeline that is not subject to the jurisdiction 

of the Commission solely by reason of Section 1(c) of the Natural Gas Act). 

Investment of municipality: The investment of the municipality in its utility department, when such investment is not subject 

to cash settlement on demand or at a fixed future time. Include the cost of debt-free utility plant constructed or acquired by 

the municipality and made available for the use of the utility department, cash transferred to the utility department for 

working capital, and other expenditures of an investment nature. 

Investments and advances to unconsolidated affiliates: The balance sheet account representing the cost of investments 

and advances to unconsolidated aff Hates. Generally, affiliates that are less than 50-percent owned by a company may not 

be consolidated into the company's financial statements. 

Investor-owned utility (IOU): A privately-owned electric utilitywhose stock is publicly traded. It is rate regulated and 

authorized to achieve an allowed rate of return. 

Ion exchange: Reversible exchange of ions adsorbed on a mineral or synthetic polymer surface with ions in solution in 

contact with the surface. A chem ical process used for recovery of uranium from solution bythe interchange of ions between 

a solution and a solid, commonlya resin. 

IOU: SeeInvestor-Owned Utility 

IPP: SeeIndependent Power Producer 

Iron and steel industry: Steel Works, Blast Furnaces (Including Coke Ovens), and Rolling Mills Establishments primarily 

engaged in manufacturing hot metal, pig iron, and silvery pig iron from iron ore and iron and steel scrap; converting pig iron, 

scrap iron, and scrap steel into steel; and in hot-rolling iron and steel into basic shapes, such as plates, sheets, strips, 

rods, bars, and tubing. 

Irradiated nuclear fuel: Nuclear fuel that has been exposed to radiation in the reactor core at any power level. 

ISO: SeeIndependent System Operator 

Isobutane (C#11 0): A normally gaseous branch-chain hydrocarbon. It is a colorless paraffinic gas that boils at a 

temperature of 10.9 degrees Fahrenheit. It is extracted from natural gas or refinery gas streams. 

Isobutylene (COM: An olefinic hydrocarbon recovered from refinery processes or petrochemical processes. 

Isohexane (C6H14): Asaturated branch-chain hydrocarbon. It is a colorless liquid that boils at a temperature of 156.2 

degrees Fahrenheit. 

Isomerization: A refining process that alters the fundamental arrangement of atoms in the molecule without adding or 

removing anything from the original material. Used to convert normal butane into isobutane (C4), an alkylation process 

feedstock, and normal pentane and hexane into isopentane (C5) and isohexane (C6), high-octane gasoline components. 

Isopach: Aline on a map drawn through points of equal thickness of a designated unit (such as a coal bed). 

Isopentane: Asaturated branched-chain hydrocarbon (C5H12) obtained by fractionation of natural gasoline or 

isomerization of normal pentane. 

Isotopes: Forms of the same chemical element that differ only by the number of neutrons in their nucleus. Most elements 

have more than one naturally occurring isotope. Many isotopes have been produced in reactors and scientific laboratories. 

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J 

Jacket: The enclosure on a water heater, f , or boiler. 

Jet fuel: A refined petroleum product used in jet aircraft engines. It includes kerosene-type jet fuel and naphtha-type jet f I. 

Joint Implementation (JI): Agreements made between two or more nations under the auspices of the Framework 

Convention on Climate Change (FCCC) whereby a developed country can receive "emissions reduction units" when it helps 

to finance projects that reduce net emissions in another developed country (including countries with economies in 

transition). 

Joint-use facility: A multiple-purpose hydroelectric plant. An example is a dam that stores water for both flood control and 

power production. 

Joule (J): The meter-kilogram-second unit of work or energy, equal to the work done by a force of one newton when its 

point of application moves through a distance of one meter in the direction of the force; equivalent to 107 ergs and one wattsecond. 

Joule's Law: The rate of heat production by a steady current in any part of an electrical circuit that is proportional to the 

resistance and to the square of the current, or, the internal energy of an ideal gas depends only on its temperature. 

Junction: A region of transition between semiconductor layers, such as a p/n junction, which goes from a region that has a 

high concentration of acceptors (p-type) to one that has a high concentration of donors (n-type). 

Jurisdictional utilities: Utilities regulated by public laws. 

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K 

Kaplan turbine: A type of turbine that that has two blades whose pitch is adjustable. The turbine may have gates to control 

the angle of the fluid flow into the blades. 

Kerosene: Alight petroleum distillate that is used in space heaters, cook stoves, and water heaters and is suitable for use 

as a light source when burned in wick-fed lamps. Kerosene has a maximum distillation temperature of 400 degrees 

Fahrenheit at the 10-percent recovery point, a final boiling point of 572 degrees Fahrenheit, and a minimum flash point of 

100 degrees Fahrenheit. Included are No. 1-K and No. 2-K, the two grades recognized by ASTM Specification D 3699 as 

well as all other grades of kerosene called range or stove oil, which have properties similar to those of No. 1 fuel oil. Also 

see Kerosene-t fuel. 

Kerosene-type jet fuel: A kerosene-based product having a maximum distillation temperature of 400 degrees Fahrenheit 

at the 10-percent recovery point and a final maximum boiling point of 572 degrees Fahrenheit and meeting ASTM 

Specification D 1655and Military Specifications MIL-T-5624P and MIL-T-83133D (Grades JP-5and JP-8). It is used for 

commercial and military turbo jet and turbo prop aircraft engines. 

• Commercial: Kerosene-type jet fuel intended for use in commercial aircraft. 

• Military: Kerosene-type jet f I intended for use in military aircraft. 

Ketone-alcohol (cy lohexanol): An oilylorless, hygroscopic liquid with a camphor-like odor. Used in soap making, dry 

cleaning, plasticizers, insecticides, and germicides. 

Kilovolt-Ampere (kVa): A unit of apparent power, equal to 1,000 volt-amperes; the mathematical product of the volts and 

amperes in an electrical circuit. 

Kilowatt (kW): One thousand watts. 

Kilowatt-electric (kWe): One thousand watts of electric capacity. 

Kilowatthour (kWh): A measure of electricity defined as a unit of work or energy, measured as 1 kilowatt (1,000watts) of 

power expended for 1 hour. One kWh is equivalent to 3,412 Btu. 

Kinetic energy: Energy available as a result of motion that varies directly in proportion to an object's mass and the square 

of its velocity. 

kVa: SeeKilovolt-Ampere 

kW: Seekilowatt 

kWe: Seekilowatt-electric 

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kWh: Seekilowatthour 

Kyoto Protocol: The result of negotiations at the third Conference of the Parties (COP-3) in Kyoto, Japan, in December 

of1997. The Kyoto Protocol sets binding greenhouse gas emissions targets for countries that sign and ratify the agreement. 

The gases covered under the Protocol include carbon diwdde, methane, nitrous ()Ade, hydrofluorocarbons (HFCs), per 

fluorocarbons (PFCs) and sulf luoride. 

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L 

Lamp: A term generally used to describe artificial light. The term is often used when referring to a "bulb" or "tube." 

Land use: The ultimate uses to be permitted for currently contaminated lands, waters, and structures at each Department 

of Energy installation. Land-use decisions will strongly influence the cost of environmental management. 

Land-use restrictions: Constraints placed upon mining bysocietal policies to protect surface features or entities that could 

be affected by m ining. Because laws and regulations may be modified or repealed, the restrictions, including industrial and 

environmental restrictions, are subject to change. 

Landfill gas: Gas that is generated by decomposition of organic material at landfill disposal sites. The average 

composition of landfill gas is approximately 50 percent methane and 50 percent carbon dioxide and water vapor by volum e. 

The methane percentage, however, can vary from 40 to 60 percent, depending on several factors including waste 

composition (e.g. carbohydrate and cellulose content). The methane in landfill gas may be vented, flared, corn busted to 

generate electricity or useful thermal energy on-site, or injected into a pipeline for combustion off-site. 

Langley: A unit or measure of solar radiation; 1 calorie per square centimeter or 3.69 Btu per square foot. 

Large passenger car: A passenger car with more than 120 cubic feet of interior passenger and luggage volume. 

Large pickup truck: A pickup truck weighing between 4,500-8,500 lbs gross vehicle weight (GVW). 

Latitude and longitude: The distance on the earth's surface measured, respectively, north or south of the equator and east 

or west of the standard meridian, expressed in angular degrees, minutes, and seconds. 

lb: Pound 

LDC: SeeLocal Distribution Company. 

Leachate: The liquid that has percolated through the soil or other medium. 

Lead acid battery: An electrochemical batter that uses lead and lead oxide for electrodes and sulf the 

electrolyte. 

Leaded gasoline: Afuel that contains more than0.05 gram of lead per gallon or more than 0.005 gram of phosphorus per 

gallon. 

Leaded premium gasoline: Gasoline having an antiknock index (R+M/2) greater than 90 and containing more than 0.05 

grams of lead or 0.005 grams of phosphorus per gallon. 

Leaded regular gasoline: Gasoline having an antiknock index (R+M/2) greater than or equal to 87 and less than or equal to 

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90 and containing more than 0.05 grams of lead or 0.005 grams of phosphorus per gallon. 

Leading edge: In reference to a wind energy conversion system, the area of a turbine blade surface that first comes into 

contact with the wind. 

Lease and plant fuel: Natural gas used in well, field, and lease operations (such as gas used in drilling operations, 

heaters, dehydrators, and field compressors) and as fuel in natural gas processing plants. 

Lease condensate: A mixture consisting primarilyof hydrocarbons heavier than pentanes that is recovered as a liquid from 

natural gas in lease separation facilities. This category excludes natural gas plant liquids, such as butane and propane, 

which are recovered at downstream natural gas processing plants or facilities. 

Lease equipment: All equipment located on the lease except the well to the point of the "Christmas tree." 

Lease fuel: Natural gas used in well, field, and lease operations, such as gas used in drilling operations, heaters, 

dehydrators, and field compressors. 

Lease operations: Any well, lease, or field operations related to the exploration for or production of natural gas prior to 

delivery for processing or transportation out of the field. Gas used in lease operations includes usage such as for drilling 

operations, heaters, dehydraters, field compressors, and net used for gas lift. 

Lease separation facility: Afacility installed at the surface for the purpose of (a) separating gases from produced crude oil 

and water at the temperature and pressure conditions set by the separator and/or (b) separating gases from that portion of 

the produced natural gas stream that liquefies at the temperature and pressure conditions set by the separator. 

Lease separator: Afacility installed at the surface for the purpose of separating the full well stream volume into two or three 

parts at the temperature and pressure conditions set by the separator. For oil wells, these parts include produced crude oil, 

natural gas, and water. For gas wells, these parts include produced natural gas, lease condensate, and water. 

Leasehold reserves: Natural gas liquid reserves corresponding to the leasehold production defined above. 

Lessee: An independent marketer who leases the station and land and has use of tanks, pumps, signs, etc. A lessee 

dealer typically has a supplyagreement with a refiner or distributor and purchases products at dealer tank-wagon prices. 

The term "lessee dealer" is limited to those dealers who are supplied directly by are finer or any affiliate or subsidiary of the 

reporting company. "Direct supply' includes use of commission agent or common carrier delivery. 

Levelized cost: The present value of the total cost of building and operating a generating plant over its economic life, 

converted to equal annual payments. Costs are levelized in real dollars (i.e., adjusted to remove the impact of inflation). 

Leverage ratio: A measure that indicates the financial abilityto meet debt service requirements and increase the value of 

the investment to the stockholders. (i.e., the ratio of total debt to total assets). 

LEVP: Low Emissions Vehicle Program. 

LHV: Lower Heating Value. 

Liability: An amount payable in dollars or by future services to be rendered. 

Licensed site capacity: Capacity (number of assemblies) for which the site is currently licensed. 

Licensees: Entitythat has been granted permission to engage in an activity otherwise unlawful (i.e., hydropower project). 

Life extension: Restoration or refurbishment of a plant to its original performance without the installation of new 

combustion technologies. Life extension results in 10 to 20 years of plant life beyond the anticipated retirement date, but 

usually does not result in larger capacity. 

Lift: The force that pulls a wind turbine blade, as opposed to drag. 

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Lifting costs: The costs associated with the extraction of a mineral reserve from a producing property. 

Light bulbs: A term generally used to describe a man-made source of light. The term is often used when referring to a 

"bulb" or "tube". 

Light gas oils: Liquid petroleum distillates heavier than naphtha, with an approximate boiling range from 401 degrees to 

650 degrees Fahrenheit. 

Light rail: An electric railway with a "light volume" traffic capacity compared to "heavy rail." Light rail may use exclusive or 

shared rights-of-way, high or low platform loading, and multi-car trains or single cars. Also known as "street car," "trolley 

car," and "tramway." 

Light trucks: All single unit two-axle, four-tire trucks, including pickup trucks, sports utility vehicles, vans, motor homes, etc. 

This is the Department of Transportation definition. The Energy Information Administration defined light truck as all trucks 

weighing 8,500 pounds or less. 

Light water: Ordinary water (H2O), as distinguished from heavy water or deuterium oxide (020). 

Light water reactor (LWR): A nuclear reactor that uses water as the primary coolant and moderator, with slightly enriched 

uranium as fuel. 

Light-duty vehicles: Vehicles weighing less than 8,500 lbs (include automobiles, motorcycles, and light trucks). 

Lighting conservation feature: A building feature or practice designed to reduce the amount of energy consumed by the 

lighting system. 

Lighting Demand-Side Management (DSM) program: ADSM program designed to promote efficient lighting systems in 

new construction or existing facilities. Lighting DSM programs can include: certainty -efficiency fluorescent 

fixtures including T-8 lamp technology, solid state electronic ballasts, specular reflectors, compact fluorescent f tures, LED 

and electro-luminescent Emergency Exist Signs, High Pressure Sodium with switchable ballasts, Compact Metal Halide, 

occupancy sensors, and daylighting controllers. 

Lighting equipment: These are light bulbs used to light the building's interior, such as incandescent light bulbs, 

fluorescent light bulbs, compact fluorescent light bulbs, and high-intensitydischarge (HID) lights. 

Lights: All of the light bulbs controlled by one switch are counted as one light. For example, a chandelier with multiple lights 

controlled by one switch is counted as one light. Afloor lamp with two separate globes or bulbs controlled by two separate 

switches would be counted as two lights. Indoor and outdoor lights were counted if they were under the control of the 

householder. This would exclude lights in the hallway of multi-family buildings. 

Lignite: The lowest rank of coal, often referred to as brown coal, used almost exclusively as fuel for steam-electric power 

generation. It is brownish-black and has a high inherent moisture content, sometimes as high as 45 percent The heat 

content of lignite ranges from 9 to 17 million Btu per ton on a moist, mineral-matter-free basis. The heat content of lignite 

consumed in the United States averages 13 million Btu per ton, on the as-received basis (i.e. containing both inherent 

moisture and mineral matter). 

LIHEAP: Low-Income Home EnergyAssistance Program. 

Line loss: Electric energy lost because of the transmission of electricity. Much of the loss is thermal in nature. 

Line-miles of seismic exploration: The distance along the Earth's surface that is covered by seism ic surveying. 

Liquefied natural gas (LNG): Natural gas (primarily methane) that has been liquefied by reducing its temperature to -260 

degrees Fahrenheit at atmospheric pressure. 

Liquefied petroleum gases: A group of hydrocarbon-based gases derived from crude oil refining or natural gas 

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f . They include ethane, ethylene, propane, propylene, normal butane, butylene, isobutane, and isobutylene. For 

convenience of transportation, these gases are liquefied through pressurization. 

Liquefied refinery gases (LRG): Liquefied petroleum gases fractionated from refinery or still gases. Through compression 

and/or refrigeration, they are retained in the liquid state. The reported categories are ethane/ethylene, propane/propylene, 

normal butane/butylene, and isobutane/isobutylene. Excludes still gas. 

Liquid collector: A medium-temperature solar thermal collector, employed predominantly in water heating, which uses 

pumped liquid as the heat-transfer medium. 

Liquid fuels: All petroleum products, natural gas liquids, biofuels, and liquids derived from other hydrocarbon sources (coal 

to liquids and gas to liquids). Not included arecompressed natural gas (CNG), liquefied natural gas (LNG), and hydrogen. 

Liquid metal f lear breeder reactor, cooled by molten sodium, in which fission is caused by fast 

neutrons. 

LNG: SeeLiquefied Natural Gas. 

Load (electric): An end-use device or customer that receives power from the electric system. SeeNERC definition. 

Load control program: A program in which the utility company offers a lower rate in return for having permission to turn off 

the air conditioner or water heater for short periods of time by remote control. This control allows the utility to reduce peak 

demand. 

Load curve: The relationship of power supplied to the time of occurrence. Illustrates the varying magnitude of the load 

during the period covered. 

Load diversity: The difference between the peak of coincident and noncoincident demands of two or more individual loads. 

Load factor: The ratio of the average load to peak load during a specified time interval. 

Load following: Regulation of the power output of electric generators within a prescribed area in response to changes in 

system frequency, tie line loading, or the relation of these to each other, so as to maintain the scheduled system frequency 

and/or established interchange with other areas within predetermined limits. 

Load leveling: Any load control technique that dampens the cyclical daily load flows and increases baseload generation. 

Peak load pricing and time-of-day charges are two techniques that electric utilities use to reduce peak load and to maximize 

eff lectricity. 

Load loss (3 hours): Any significant incident on an electric utility system that results in a continuous outage of 3 hours or 

longer to more than 50,000 customers or more than one half ofthe total customers being served immediately prior to the 

incident, whichever is less. 

Load management technique: Utility demand management practices directed at reducing the maximum kilowatt demand 

on an electric system and/or modifying the coincident peak demand of one or more classes of service to better meet the 

utility system capability for a given hour, day, week, season, or year. 

Load on equipment: One hundred percent load is the maximum continuous net output of the unit at normal operating 

conditions during the annual peak load month. For example, if the equipment is capable of operating at 5% over pressure 

continuously, use this condition for 100% load. 

Load reduction request: The issuance of any public or private request to any customer or the general public to reduce the 

use of electricity for the reasons of maintaining the continuity of service of the reporting entity's bulk electric power supply 

system. Requests to a customer(s) served under provisions of an interruptible contract are not a reportable action unless 

the request is made for reasons of maintaining the continuity of service of the reporting entity's bulk electric power supply. 

Load shape: A method of describing peak load demand and the relationship of power supplied to the time of occurrence. 

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Load shedding: Intentional action bya utility that result f more than 100 megawatts (MW) of firm 

customer load for reasons of maintaining the continuity of service of the reporting entity's bulk electric power supply system. 

The routine use of load control equipment that reduces firm customer load is not considered to be a reportable action. 

Load-serving entity (electric): Secures energy and transmission service (and related Interconnect Operations Services) to 

serve the electrical demand and energy requirements of its end-use customers. See NERC definition. 

Local distribution company (LDC): A legal entity engaged primarily in the retail sale and/or delivery of natural gas through a 

distribution system that includes main lines (that is, pipelines designed to carry large volumes of gas, usually located under 

roads or other major right-of-ways) and laterals (that is, pipelines of smaller diameter that connect the end user to the 

mainline). Since there structuring of the gas industry, the sale of gas and/or delivery arrangements may be handled by other 

agents, such as producers, brokers, and marketers that are referred to as "non-LDC." 

Long ton: Aunit that equals 20 long hundred weight or 2,240 pounds. Used mainly in England. 

Long-term debt: Debt securities or borrowing shaving a maturity of more than one year. 

Long-term purchase: A purchase contract under which at least one delivery of material is scheduled to occur during the 

second calendar year after the contract-signing year. Deliveries also can occur during the contract-signing year, during the 

first calendar year there after, or during anysubsequent calendar year. 

Longwall mining: An automated form of underground coal mining characterized by high recovery and extraction rates, 

feasible only in relativelyflat-ly !beds. A high-powered cutting machine is passed across the 

exposed face of coal, shearing away broken coal, which is continuously hauled away bya floor-level conveyor system. 

Longwall mining extracts all machine-minable coal between the floor and ceiling within a contiguous block of coal, known 

as a panel, leaving no support pillars within the panel area. Panel dimensions vary over time and with mining conditions but 

currently average about 900 feet wide (coal face width) and more than 8,000 feet long (the minable extent of the panel, 

measured indirection of mining). Longwall mining is done under movable roof supports that are advanced as the bed is cut. 

The roof in the mined-out area is allowed to fall as the mining advances. 

Loop flow: The movement of electric power from generator to load by dividing along multiple parallel paths; it especially 

refers to power flow along an un intended path that loops awayfrom the most direct geographic path or contract path. 

Loss of service (15 minutes): Any loss in service for greater than 15 minutes by an electric utility of firm loads totaling more 

than 200 MW, or 50 percent of the total load being supplied immediately prior to the incident, whichever is less. However, 

utilities with a peak load in the prior year of more than 3000 MW are only to report losses of service to firm loads totaling 

more than 300 MW for greater than 15 minutes. (The DOE shall be notified with service restoration and in any event, within 

three hours after the beginning of the interruption.) 

Low Btu gas: Afuel gas with a heating value between 90 and 200 Btu per cubic foot. 

Low E glass: Low-emission glass reflects up to 90% of long-wave radiation, which is heat, but lets in short-wave radiation, 

which is light. Windows are glazed with a coating that bonds a microscopic, transparent, metallic substance to the inside 

surface of the double-pane or triple-pane windows. 

Low flow showerheads: Reduce the amount of water flow through the showerhead from 5 to 6 gallons a minute to 3 

gallons a minute. 

Low flush toilet: Atoilet that uses less water than a standard one during flushing, for the purpose of conserving water 

resources. 

Low head: Vertical difference of 100 feet or less in the upstream surface water elevation (headwater) and the downstream 

surface water elevation (tailwater) at a dam. 

Low Income Home Energy Assistance Program (LIHEAP): The purpose of LIHEAP is to assist eligible households to 

meet the cost of heating or cooling in residential dwellings. The Federal government provides the funds to the States that 

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administer the program. 

Low power testing: The period of time between a plants nuclear generating unit's initial f I loading date and the 

issuance of its operating (f II-power) license. The maximum level of operation during this period is 5 percent of the unit's 

thermal rating. 

Low sulfur diesel (LSD) fuel: Diesel f I containing more than 15 but less than 500 parts per million (ppm) sulf . 

Low temperature collectors: Metallic or nonmetallic collectors that generally operate at temperatures below 110 degrees 

Fahrenheit and use pumped liquid or air as the heat transfer medium. They usually contain no glazing and no insulation, 

and they are often made of plastic or rubber, although some are made of metal. 

Low volatile bituminous coal: SeeBituminous Coal. 

Low-pressure sodium lamp: Aty f lamp that produces light f tained in a bulb operating at apartial 

pressure of 0.13 to 1.3 Pascal. The yellow light and large size make them applicable to lighting streets and parking lots. 

LPG: SeeLiquefied Petroleum Gases. 

LRG: SeeLiquefied Refinery Gases. 

Lubricants: Substances used to reduce friction between bearing surfaces, or incorporated into other materials used as 

processing aids in the manufacture of other products, or used as carriers of other materials. Petroleum lubricants maybe 

produced either from distillates or residues. Lubricants include all grades of lubricating oils, from spindle oil to cylinder oil 

to those used in greases. 

Lumen: An empirical measure of the quantity of light. It is based upon the spectral sensitivity of the photosensors in the 

human eye under high (daytime) light levels. Photometrically it is the luminous flux em itted with a solid angle (1 steradian) 

bya point source having a uniform luminous intensity of 1 candela. 

Lumens/Watt (Ipw): A measure of the efficacy (efficiency) of lamps. It indicates the amount of light (lumens) emitted by the 

lamp for each unit of electrical power (Watts) used. 

LWR: SeeLight Water Reactor. 

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M 

M: Thousand 

Machine drive (motors): The direct process end use in which thermal or electric energy is converted into mechanical 

energy. Motors are found in almost every process in manufacturing. Therefore, when motors are found in equipment that is 

wholly contained in another end use (such as process cooling and refrigeration), the energy is classified there rather than 

in machine drive. 

Made available (vehicle): A vehicle is considered "Made available" if it is available for delivery to dealers or users, whether 

or not it was actually delivered to them. To be "Made available", the vehicle must be completed and available for delivery; 

thus, any conversion to be performed by an original equipment manufacturer (OEM) Vehicle Converter or Aftermarket 

Vehicle Converter must have been completed. 

Magma: Naturally occurring molten rock, generated within the earth and capable of intrusion and extrusion, from which 

igneous rocks are thought to have been derived through solidification and related processes. It mayor may not contain 

suspended solids (such as crystals and rock fragments) and/or gas phases. 

Main heating equipment: Equipment primarily used for heating ambient air in the housing unit. 

Main heating fuel: The form of energy used most frequently to heat the largest portion of the floorspace of a structure. The 

energy source designated as the main heating fuel is the source delivered to the site for that purpose, not any subsequent 

form into which it is transformed on site to deliver the heat energy (e.g., for buildings heated by a steam boiler, the main 

heating fuel is the main input fuel to the boiler, not the steam or hot water circulated through the building.) Note: In 

commercial buildings, the heating must be to at least 50 degrees Fahrenheit. 

Mains: Asystem of pipes for transporting gas within a distributing gas utilitys retail service area to points of connection with 

consumer service pipes. 

Maintenance expenses: That portion of operating expenses consisting of labor, materials, and other direct and indirect 

expenses incurred for preserving the operating efficiency and/or physical condition of utility plants used for power 

production, transmission, and distribution of energy. 

Maintenance of boiler plant (expenses): The cost of labor, material, and expenses incurred in the maintenance of a steam 

plant. Includes furnaces; boilers; coal, ash-handling, and coal-preparation equipment; steam and feed water piping; and 

boiler apparatus and accessories used in the production of steam, mercury, or other vapor to be used primarilyfor 

generating electricity. The point at which an electric steam plant is distinguished from an electric plant is defined as follows: 

1. Inlet flange of throttle valve on prime mover. 

2. Flange of all steam extraction lines on prime mover. 

3. Hot well pump outlet on condensate lines. 

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4. Inlet flange of all turbine-room awdliaries. 

5. Connection to line side of motor starter for all boiler-plant equipment. 

Maintenance of structures (expenses): The cost of labor, materials, and expenses incurred in maintenance of power 

production structures. Structures include all buildings and facilities to house, support, or safeguard property or persons. 

Maintenance supervision and engineering expenses: The cost of labor and expenses incurred in the general supervision 

and direction of the maintenance of power generation stations. The supervision and engineering included consists of the 

pay and expenses of superintendents, engineers, clerks, other employees, and consultants engaged in supervising and 

directing the maintenance of each utilityfunction. Direct supervision and engineering of specific activities, such as fuel 

handling, boiler room operations, generator operations, etc., are charged to the appropriate accounts. 

Major electric utility: A utility that, in the last 3 consecutive calendar years, had sales or transmission services exceeding 

one of the following (1) 1 million megawatthours of total annual sales; (2) 100 megawatthours of annual sales for resale; 

(3) 500 megawatthours of annual gross interchange out; or (4) 500 megawatthours of wheeling (deliveries plus losses) for 

others. 

Major energy sources: Fuels or energy sources such as electricity, f I oil, natural gas, district steam, district hot water, 

and district chilled water. District chilled water is not included in any totals for the sum of major energy sources or fuels; all 

other major fuels are included in these totals. 

Major fuels: Fuels or energy sources such as: electricity, f I oil, liquefied petroleum gases, natural gas, district steam, 

district hot water, and district chilled water. 

Major interstate pipeline company: A companywhose combined sales for resale, including gas transported interstate or 

stored for a fee, exceeded 50 million thousand cubic feet in the previous year. 

Make-up air: Air brought into a building from outside to replace exhaust air. 

MANE-VU (Mid-Atlantic/Northeast Visibility Union) : An organization formed by the Mid-Atlantic and Northeastern states, 

tribes, and federal agencies to coordinate planning activities to reduce haze (air pollution) in the region. The organization 

encourages a coordinated approach to meeting the requirements of EPA's Regional Haze Rules and reducing visibility 

impairment in major national parks and wilderness areas in the Northeast and Mid-Atlantic regions. 

http://www.otcair.org/manevu/aboutus.asp. 

Manhattan Project: The U.S. Government project that produced the first nuclear weapons during World War II. Started in 

1942, the Manhattan Project formally ended in 1946. The Hanford Site, Oak Ridge Reservation, and Los Alamos National 

Laboratorywere created for this effort. The project was named for the Manhattan Engineer District of the U.S. Army Corps of 

Engineers. 

Manual dimmer switches: These are like residential-style dimmer switches. They are not generally used with fluorescent 

and high-intensity discharge (HID) lamps. 

Manufactured gas: A gas obtained by destructive distillation of coal or by the thermal decomposition of oil, or by the 

reaction of steam passing through a bed of heated coal or coke. Examples are coal gases, coke oven gases, producer gas, 

blast f lue (water) gas, carbureted water gas. Btu content varies widely. 

Manufacturing: An energy-consuming subsector of the industrial sector that consists of all facilities and equipment 

engaged in the mechanical, physical, chemical, or electronic transformation of materials, substances, or components into 

new products. Assembly of component parts of products is included, except for that which is included in construction. 

Manufacturing division: One of 10 fields of economic activity defined by the Standard Industrial Classification Manual. The 

manufacturing division includes all establishments engaged in the mechanical or chemical transformation of materials or 

substances into new products. The other divisions of the U.S. economy are agriculture, forestr , fishing, hunting, and 

trapping; mining; construction; transportation, communications, electric, gas, and sanitary services; wholesale trade; retail 

trade; finance, insurance, and real estate; personal, business, professional, repair, recreation, and other services; and 

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public administration. The establishments in the manufacturing division constitute the universe for the MECS (an EIA 

survey). 

Manufacturing establishment: An economic unit at a single physical location where mechanical or chemical 

transformation of materials or substances into new products are performed. 

MARAMA (Mid-Atlantic Regional Air Management Association, Inc.) : A voluntary, non-profit association of ten Mid-Atlantic 

state and local air pollution control agencies. http://www.marama.org/about-us. 

Marginal cost: The change in cost associated with a unit change in quantity supplied or produced. 

Marine freight: Freight transported over rivers, canals, the Great Lakes, and domestic ocean waterways. 

Market clearing price: The price at which supply equals demand for the Day-ahead or hour-ahead markets. 

Market price contract: A contract in which the price of uranium is not specifically determined at the time the contract is 

signed but is based instead on the prevailing market price at the time of delivery. A market price contract may include a 

floorprice, that is, a lower limit on the eventual settled price. The floorprice and the method of price escalation generally are 

determined when the contract is signed. The contract may also include a price ceiling or a discount from the agreed-upon 

market price reference. 

Market price settlement (uranium): The price paid for uranium delivery under a market-price contract. The price is 

commonly (but not always) determined at or sometime before delivery and maybe related to a floor price, ceiling price, or 

discount. 

Market-based pricing: Prices of electric power or other forms of energy determined in an open market system of supply 

and demand under which prices are set solely by agreement as to what buyers will pay and sellers will accept. Such prices 

could recover less or more than full costs, depending upon what the buyers and sellers see as their relevant opportunities 

and risks. 

Marketable coke: Those grades of coke produced in delayed or fluid cokers that maybe recovered as relatively pure 

carbon. This "green" coke maybe sold as is or further purified by calcining. 

Marketed energy: An energy source that is commercially traded. Typically Id by a producer, such as a 

petroleum refiner, through a transmission and distribution network (e.g., pipelines and trucks) to an end-use consumer 

(e.g., gasoline sold at the pump). 

Marketed production: Gross withdrawals less gas used for repressuring, quantities vented and flared, and 

nonhydrocarbon gases removed in treating or processing operations. Includes all quantities of gas used in field and 

processing plant operations. 

Masonry: Ageneral term covering wall construction using masonry materials such as brick, concrete block, stone, and tile 

that are set in mortar; also included is stucco. The category does not include concrete panels because concrete panels 

represent a different method of constructing buildings. Concrete panels are reported separately. 

Masonry stove: Atype of heating appliance similar to a fireplace, but much more efficient and clean burning. They are 

made of masonryand have long channels through which combustion gases give up their heat to the heavy mass of the 

stove, which releases the heat slowly into a room. Often called Russian or Finnish fireplaces. 

Mass burn facility: Atype of municipal solid waste (MSW) incineration facility in which MSW is burned with only minor 

presorting to remove oversize, hazardous, or explosive materials. 

Master-metering: Measurement of electricity or natural gas consumption of several tenants or housing units using a single 

meter. That is, one meter measures the energy usage for several households collectively. 

Maximum deliverability: The maximum deliverability rate (Mcf/d) estimated at the present developed maximum operating 

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capacity. 

Maximum demand: The greatest of all demands of the load that has occurred within a specified period of time. 

Maximum dependable capacity, net: The gross electrical output measured at the output terminals of the turbine 

generator(s) during the most restrictive seasonal conditions, less the station service load. 

Maximum established site capacity (reactors): The maximum established spent fuel capacityfor the site is defined by 

DOE as the maxim urn number of intact assemblies that will be able to be stored at some point in the future (between the 

reporting date and the reactor's end of life) taking into account any established or current studies or engineering evaluations 

at the time of submittal for licensing approval from the NRC. 

Maximum generator nameplate capacity: The maximum rated output of a generator, prime mover, or other electric power 

production equipment under specific conditions designated by the manufacturer. 

Maximum hourly load: This is determined bythe interval in which the 60-minute integrated demand is the greatest. 

Maximum streamflow: The maximum rate of water flow past a given point during a specified period. 

MBOED: million barrels of oil equivalent per day 

Mcf: one thousand cubic feet 

Mean indoor temperature: The "usual" temperature. If different sections of the house are kept at different temperatures, the 

reported temperature is for the section where the people are. A thermostat setting is accepted if the temperature is not 

known. 

Mean operating hours: The arithmetic average number of operating hours per building is the weighted sum of the number 

of operating hours divided by the weighted sum of the number of buildings. 

Mean power output (of a wind turbine): The average power output of a wind energy conversion system at a given mean 

wind speed based on a Raleigh frequency distribution. 

Mean square feet per building: The arithmetic average square feet per building is the weighted sum of the total square feet 

divided bythe weighted sum of the number of buildings. 

Measured heated area of residence: The floor area of the housing unit that is enclosed from the weather and heated. 

Basements are included whether or not they contain finished space. Garages are included if they have a wall in common 

with the house. Attics that have finished space and attics that have some heated space are included. Crawl spaces are not 

included even if they are enclosed from the weather. Sheds and other buildings that are not attached to the house are not 

included. "Measured" area means the measurement of the dimensions of the home, using a metallic, retractable, 50-foot 

tape measure. "Heated area" is that portion of the measured area that is heated during most of the season. Rooms that are 

shut off during the heating season to save on fuel are not counted. Attached garages that are unheated and unheated areas 

in the attics and basements are also not counted. 

Measured reserves: SeeProved energy reserves. 

Measured resources, coal: Coal resources for which estimates of the rank, quality, and quantity have been computed, 

within a margin of error of less than 20 percent, from sample analyses and measurements from closelyspaced and 

geologicallywell known sample sites. Measured resources are computed from dimensions revealed in outcrops, trenches, 

mine workings, and drill holes. The points of observation and measurement are so closely spaced and the thickness and 

extent of coals are so well defined that the tonnage is judged to be accurate within 20 percent. Although the spacing of the 

points of observation necessary to demonstrate continuity of the coal differs from region to region, according to the 

character of the coalbeds, the point of observation are no greater than 1/2 mile apart. Measured coal is projected to extend 

as a belt 1/4 mile wide from the outcrop or points of observation or measurement. 

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MECS: Manufacturing Energy Consumption Survey 

Median: The middle number of a data set when the measurements are arranged in ascending (or descending) order. 

Median streamflow: The middle rate of flow of water past a given point for which there have been several greater and 

lesser rates of flow occurring during a specified period. 

Median water condition: The middle precipitation and run-off condition for a distribution of water conditions that have 

happened over a long period of time. Usually determined by examining the water supply record of the period in question. 

Medium pressure: For valves and fittings, implies that theyare suitable for working pressures between 125 to 175 pounds 

per square inch. 

Medium-temperature collector: A collector designed to operate in the temperature range of 140 degrees to 180 degrees 

Fahrenheit, but that can also operate at a temperature as low as 110 degrees Fahrenheit. The collector typically consists of 

a metal frame, metal absorption panels with integral flow channels (attached tubing for liquid collectors or integral ducting 

for air collectors), and glazing and insulation on the sides and back. 

Medium-v latile bituminous coal: SeeBituminous coal. 

Megavoltamperes (MVA): Millions of voltam peres, which are a measure of apparent power. (See definition for apparent 

power.) 

Megawatt (MW): One million watts of electricity. 

Megawatt electric (MWe): One million watts of electric capacity. 

Megawatthour (MWh): One thousand kilowatt-hours or lmillion watt-hours. 

Mercaptan: An organic chemical compound that has a sulf like odor that is added to natural gas before distribution to the 

consumer, to give it a distinct, unpleasant odor (smells like rotten eggs). This serves as a safety device by allowing it to be 

detected in the atmosphere, in cases where leaks occur. 

Merchant coke plant: Acoke plant where coke is produced primarilyfor sale on the commercial (open) market. 

Merchant facilities: High-risk, high-profit facilities that operate, at least partially, at the whims of the market, as opposed to 

those facilities that are constructed with close cooperation of municipalities and have significant amounts of waste supply 

guaranteed. 

Merchant MTBE plants: MTBE (methyl tertiary butylether) production facilities primarily located within petrochemical plants 

rather than refineries. Production from these units is sold under contract or on the spot market to refiners or other gasoline 

blenders. 

Merchant oxygenate plants: Oxygenate production facilities that are not associated with a petroleum refinery. Production 

from these facilities is sold under contract or on the spot market torefiners or other gasoline blenders. 

Mercury vapor lamp: A high-intensity discharge lamp that uses mercury as the primary light-producing element. Includes 

clear, phosphor coated, and self-ballasted lamps. 

Merger: Acombining of companies or corporations into one, often by issuing stock of the controlling corporation to replace 

the greater part of that of the other. 

Met: An approximate unit of heat produced by a resting person, equal to about 18.5 Btu per square foot per hour. 

Meta-anthracite: SeeAnthracite. 

Metal halide lamp: A high-intensity discharge lamp type that uses mercury and several halide additives as light-producing 

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elements. These lights have the best Color Rendition Index (CRI) of the high-intensity discharge lamps. They can be used 

for commercial interior lighting or for stadium lights. 

Metallic: The metallic material composition of the collector's absorber system. 

Metallurgical coal: Coking coal and pulverized coal consumed in making steel. 

Metered data: End-use data obtained through the direct measurement of the total energy consumed for specific uses 

within the individual household. Individual appliances can be submetered by connecting the recording meters directlyto 

individual appliances. 

Metered peak demand: The presence of a device to measure the maximum rate of electricity consumption per unit of time. 

This device allows electric utility companies to bill their customers for maximum consumption, as well as for total 

consumption. 

Methane: Acolorless, flammable, odorless hydrocarbon gas (CH4) which is the major component of natural gas. It is also 

an important source of hydrogen in various industrial processes. Methane is a greenhouse gas. See also Greenhouse 

gases. 

Methanogens: Bacteria that synthesize methane, requiring completely anaerobic conditions for growth. 

Methanol (CH3OH): Alight, volatile alcohol eligible for gasoline blending. 

Methanol blend: Mixtures containing 85 percent or more (or such other percentage, but not less than 70 percent) by volum e 

of methanol with gasoline. Pure methanol is considered an "other alternative fuel." 

Methanotrophs: Bacteria that use methane as food and oxidize it into carbon dioxide. 

Methyl chloroform (trichloroethane): An industrial chemical (CH3CC13) used as a solvent, aerosol propellant, and 

pesticide and for metal degreasing. 

Methylene chloride: A colorless liquid, nonexplosive and practically nonflammable. Used as a refrigerant in centrifugal 

compressors, a solvent for organic materials, and a component in nonflammable paint removers. 

Metric conversion factors (for floorspace): Floorspace estimates maybe converted to metric units by using the 

relationship, 1 square foot is approximately equal to .0929 square meters. Energy estimates maybe converted to metric 

units by using the relationship, 1 Btu is approximately equal to 1,055 joules. One kilowatthour is exactly 3,600,000 joules. 

One gigajoule is appro)dmately278 kilowatthours (kWh). 

Metric ton: A unit of weight equal to 2,204.6 pounds. 

Metropolitan: Located within the boundaries of a metropolitan area. 

Metropolitan area: A geographic area that is a metropolitan statistical area or a consolidated metropolitan statistical area 

as defined bythe U.S. Office of Management and Budget. 

Metropolitan statistical area (MSA): A county or group of contiguous counties (towns and cities in New England) that has 

(1) at least one citywith 50,000 or more in habitants; or (2) an urbanized area of 50,000 inhabitants and a total population of 

100,000 or more inhabitants (75,000 in New England). These areas are defined by the U.S. Off f Management and 

Budget. The contiguous counties or other jurisdictions to be included in an MSA are those that, according to certain criteria, 

are essentially metropolitan in character and are socially and economically integrated with the central city or urbanized area. 

Microcrystalline wax: Wax extracted from certain petroleum residues having a finer and less apparent crystalline structure 

than paraffin wax and having the following physical characteristics penetration at 77 degrees Fahrenheit (D1321)-60 

maximum; viscosity at 210 degrees Fahrenheit in Saybolt Universal Seconds (SUS); (D88)-60 SUS (10.22 centistokes) 

minimum to 150 SUS (31.8 centistokes) maximum; oil content (D721)-5 percent minimum. 

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Microgroove: Asmall groove scribed into the surface of a solar photovoltaic cell which is filled with metal for contacts. 

Micrometer (or Micron): One-millionth of a meter. It can also be expressed as 10-6 meter. 

Microwave oven: A household cooking appliance consisting of a compartment designed to cook or heat food by means of 

microwave energy. It may also have a browning coil and convection heating as additional features. 

Mid-size passenger car: A passenger car with between110 and 119 cubic feet of interior passenger and luggage volume. 

Middle distillates: Ageneral classification of refined petroleum products that includes distillate fuel oil and kerosene. 

Middlings: In coal preparation, this material called mid-coal is neither clean nor refuse; due to their intermediate specific 

gravity lings sink only partway in the washing vessels and are removed byawdliary means. 

Midgrade gasoline: Gasoline having an antiknock index, i.e., octane rating, greater than or equal to 88 and less than or 

equal to 90. Note: Octane requirements mayvary by altitude. 

Miles per gallon (MPG): A measure of vehicle fuel efficiency. Miles per gallon or MPG represents "Fleet Miles per Gallon. 

"For each subgroup or "table cell," MPG is computed as the ratio of the total number of miles traveled by all vehicles in the 

subgroup to the total number of gallons consumed. MPGs are assigned to each vehicle using the EPAcertification files and 

adjusted for on-road driving. 

Military use: Includes sales to the Armed Forces, including volumes sold to the Defense Fuel Supply Center (DFSC) for 

use by all branches of the Department of Defense (DOD). 

Mill: A monetary cost and billing unit used by utilities; it is equal to 1/1000 of the U.S. dollar (equivalent to 1/10of 1 cent). 

Mill capital: Cost for transportation and equipping a plant for processing ore or other feed materials. 

Mill f lied to a crusher or grinding mill in an ore-dressing process. 

Milling: The grinding or crushing of ore, concentration, and other beneficiation, including the removal of valueless or 

harmful constituents and preparation for market. 

Milling capacity: The maximum rate at which a mill is capable of treating ore or producing concentrate. 

Milling of uranium: The processing of uranium from ore mined by conventional methods, such as underground or open-pit 

methods, to separate the uranium from the undesired material in the ore. 

Million British Thermal Units: MMBtu. SeeBtu. 

Minable: Capable of being mined under current mining technology and environmental and legal restrictions, rules, and 

regulations. 

Mine capital: Cost for exploration and development, pre-mining stripping, shaft sinking, and mine development (including 

in-situ leaching), as well as the mine plant and its equipment. 

Mine count: The number of mines, or mines collocated with preparation plants or tipples, located in a particular geographic 

area (state or region). If a mine is mining coal across two counties within a state, or across two states, then it is counted as 

two operations. This is done so that ElAcan separate production by state and county. 

Mineral: Any of the various naturally occurring in organic substances, such as metals, salt, sand, stone, sulf , and water, 

usually obtained from the earth. Note For reporting on the Financial Reporting System the term also includes organic nonrenewable substances that are extracted from the earth such as coal, crude oil, and natural gas. 

Mineral lease: An agreement wherein a mineral interest owner (lessor) conveys to another party (lessee) the rights to 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

operating interest in the property, referred to as the royalt , each in proportions agreed upon. 

Mineral rights: The ownership of the minerals beneath the earth's surface with the right to remove them. Mineral rights may 

be conveyed separatelyfrom surface rights. 

Mineral-matter-free basis: Mineral matter in coal is the parent material in coal from which ash is derived and which comes 

from minerals present in the original plant materials that formed the coal, or from extraneous sources such as sediments 

and precipitates from mineralized water. Mineral matter in coal cannot be analyticallydetermined and is commonly 

calculated using data on ash and ash-forming constituents. Coal analyses are calculated to the mineral matter free basis 

byadjusting formulas used in calculations in order to deduct the weight of mineral matter from the total coal. 

Minimum streamflow: The lowest rate of flow of water past a given point during a specified period. 

Mining: An energy-consuming subsector of the industrial sector that consists of all facilities and equipment used to extract 

energy and mineral resources. 

Mining operation: One mine and/or tipple at a single physical location. 

Minivan: Small van that flrst appeared with that designation in 1984. Any of the smaller vans built on an automobile-type 

frame. Earlier models such as the Volkswagen van are now included in this category. 

Minority carrier: A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor 

material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device. 

Miscellaneous petroleum products: Includes all finished products not classified elsewhere (e.g., petrolatum lube refining 

byproducts (aromatic extracts and tars), absorption oils, ram-jet fuel, petroleum rocket fuels, synthetic natural gas feed 

stocks, and specialtyoils). 

Miscellaneous reserves: Asupply source having not more than 50 billion cubic feet of dedicated recoverable salable 

reserves and that falls within the definition of Supply Source. 

Mixed waste: Waste containing both radioactive and hazardous constituents. 

MM: million (106

) 

MMbbikl: one million (106) barrels of oil per day 

MMBtu: one million (106) British thermal units 

MMcf: one million (106) cubic feet 

MMgal/d: one million (106

) gallons per day 

MMst: one million (106) short tons 

Mobile home: A housing unit built on a movable chassis and moved to the site. It maybe placed on a permanent or 

temporary foundation and may contain one room or more. If rooms are added to the structure, it is considered a singlefamily housing unit. Amanufactured house assembled on site is a single-family housing unit, not a mobile home. 

Moderator: A material, such as ordinarywater, heavy water, or graphite, used in a reactor to slow down high-velocity 

neutrons, thus increasing the likelihood of further fission. 

Modules: Photovoltaic cells or an assemblyof cells into panels (modules) intended for and shipped for final consumption 

or to another organization for resale. When exported, incomplete modules and unencapsulated cells are also included. 

Modules used for space applications are not included. 

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Moist (coal) basis: Moist coal contains its natural inherent or bed moisture, but does not include water adhering to the 

surface. Coal analyses expressed on a moist basis are performed or adjusted so as to describe the data when the coal 

contains only that moisture that exists in the bed in its natural state of deposition and when the coal has not lost any 

moisture due to drying. 

Moisture content: The water content of a substance (a solid fuel) as measured under specified conditions being the "dry 

basis," which equals the weight of the wet sample minus the weight of a (bone) dry sample divided bythe weight of the dry 

sample times 100 (to get percent); "wet basis," which is equal to the weight of the wet sample minus the weight of the dry 

sample divided by the weight of the wet sample times 100. 

Mole: The quantity of a compound or element that has a weight in grams numerically equal to its molecular weight. Also 

referred to as "gram molecule" or "gram molecular weight." 

Montreal protocol: The Montreal Protocol on Substances that Deplete the Ozone Layer (1987). An international agreement, 

signed by most of the industrialized nations, to substantially reduce the use of chlorofluorocarbons (CFCs). Signed in 

January 1989, the original document called for a 50-percent reduction in CFC use by 1992 relative to 1986 levels. The 

subsequent London Agreement called for a complete elimination of CFC use by 2000. The Copenhagen Agreement, which 

called for a complete phase out byJanuary 1, 1996, was implemented by the U.S. Environmental Protection Agency. 

Motor gasoline (finished): A complex m ixture of relatively volatile hydrocarbons with or without small quantities of additives, 

blended to form a fuel suitable for use in spark-ignition engines. Motor gasoline, as defined in ASTM Specification D 4814 

or Federal Specification W-G-1690C, is characterized as having a boiling range of 122 to 158 degrees Fahrenheit at the 10 

percent recovery point to 365 to 374 degrees Fahrenheit at the 90 percent recovery point. Motor Gasoline includes 

conventional gasoline; all t line, including gasohol; and reformulated gasoline, but excludes 

aviation gasoline. Note: Volumetric data on blending components, such as oxygenates, are not counted in data on finished 

motor gasoline until the blending components are blended into the gasoline. 

Motor gasoline blending: Mechanical mixing of motor gasoline blending components, and oxygenates when required, to 

produce finished motor gasoline. Finished motor gasoline maybe further mixed with other motor gasoline blending 

components or oxygenates, resulting in increased volumes of finished motor gasoline and/or changes in the formulation of 

finished motor gasoline (e.g., conventional motor gasoline mixed with MTBE to produce oxygenated motor gasoline). 

Motor gasoline blending components: Naphthas (e.g., straight-run gasoline, alkylate, reformate, benzene, toluene, xylene) 

used for blending or compounding into finished motor gasoline. These components include reformulated gasoline blend 

stock for oxygenate blending (RBOB) but exclude oxygenates (alcohols, ethers), butane, and pentanes plus. Note 

Oxygenates are reported as individual components and are included in the total for other hydrocarbons, hydrogens, and 

oxygenates. 

Motor speed: The number of revolutions that the motor turns in a given time period (i.e. revolutions per minute, rpm). 

MPG: SeeMiles Per Gallon 

MPG shortfall: The difference between actual on-road MPG and EPA laboratory test MPG. MPG short fall is expressed as 

gallons per mile ratio (GPMR). 

MSA: SeeMetropolitan Statistical Area 

MSHA: Mine Safety and Health Administration 

MSHA ID number: Seven (7)-digit code assigned to a mining operation by the Mine Safety and Health Administration. 

MSW: SeeMunicipal Solid Waste 

MTBE: Methyl Tertiary Butyl Ether 

MTBE (methyl tertiary butyl ether) (CH3)3COCH3: An ether intended for gasoline blending as described in "Oxygenates." 

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Multiple completion well: Awell equipped to produce oil and/or gas separately from more than one reservoir. Such wells 

contain multiple strings of tubing or other equipment that permit production from the various completions to be measured 

and accounted for separately. For statistical purposes, a multiple completion well is reported as one well and classified as 

either an oil well or a gas well. If one of the several completions in a given well is an oil completion, the well is classified as 

an oil well. If all of the completions in a given well are gas completions, the well is classified as a gas well. 

Multiple cropping: Asystem of growing several crops on the same field in one year. 

Multiple purpose project: The development of hydroelectric facilities to serve more than one function. Some of the uses 

include hydroelectric power, irrigation, water supply, water quality control, and/or fish and wildlife enhancement. 

Multiple purpose reservoir: Stored water and its usage governed by advanced water resource conservation practices to 

achieve more than one water control objective. Some of the objectives include flood control, hydroelectric power 

development, irrigation, recreation usage, and wilderness protection. 

Municipal solid waste: Residential solid waste and some nonhazardous commercial, institutional, and industrial wastes. 

Municipal waste: As defined in the Energy SecurityAct (P.L. 96-294; 1980) as "anyorganic matter, including sewage, 

sewage sludge, and industrial or commercial waste, and mixtures of such matter and inorganic refuse from any publicly or 

privately operated municipal waste collection or similar disposal system, or from similar waste flows (other than such flows 

which constitute agricultural wastes or residues, or wood wastes or residues from wood harvesting activities or production 

of forest products)." 

Municipal waste to energy project or plant: A facility that produces fuel or energy from municipal solid waste. 

Municipality: Avillage town, city, county, or other political subdivision of a State. 

MW: SeeMegawatt 

MWe: SeeMegawatt electric 

MWh: SeeMegawatthour 

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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

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N 

N20: Nitrous Oxide 

NAAQS: National Ambient Air Quality Standards 

NAICS (North American Industry Classification System): A coding system developed jointly by the United States, Canada, 

and Mexico to classify businesses and industries according to the type of economic activity in which they are engaged. 

NAICS replaces the Standard Industrial Classification (SIC) codes. 

Name plate: A metal tag attached to a machine or appliance that contains information such as brand name, serial number, 

voltage, power ratings under specified conditions, and other manufacturer supplied data. 

Name plate capacity: SeeGenerator name plate capacity (installed). 

Naphtha: A generic term applied to a petroleum fraction with an approximate boiling range between 122 degrees 

Fahrenheit and 400 degrees Fahrenheit. 

Naphtha less than 401 degrees Fahrenheit: SeePetrochemical feedstocks. 

Naphtha-type jet fuel: Afuel in the heavy naphtha boiling range having an average gravity of 52.8 degrees API, 20 to 90 

percent distillation temperatures of 290 degrees to 470 degrees Fahrenheit, and meeting Military Specification MIL-T-5624L 

(Grade JP-4),It is used primarilyfor militaryturbojet and turboprop aircraft engines because it has a lower freeze point than 

other aviation fuels and meets engine requirements at high altitudes and speeds. Note: Beginning with January 2004 data, 

naphtha-t I is included inMiscellaneous Products. 

Naphthas: Refined or partly refined light distillates with an approximate boiling point range of 27 degrees to 221 degrees 

Centigrade. Blended further or mixed with other materials, they make high-grade motor gasoline or jet fuel. Also, used as 

solvents, petrochemical feedstocks, or as raw materials for the production of town gas. 

NARUC: SeeNational Association of Regulatory Utility Commissioners. 

National Association of Regulatory Utility Commissioners (NARUC): An affiliation of the public service commissioners to 

promote the uniform treatment of members of the railroad, public utilities, and public service commissions of the 50 states, 

the District of Columbia, the Commonwealth of Puerto Rico, and the territory of the Virgin Islands. 

National Defense Authorization Act: The federal law, enacted in 1994 and amended in 1995, that required the Secretary of 

Energy to prepare the Baseline Report. 

National priorities list: The Environmental Protection Agencys list of the most serious uncontrolled or abandoned 

hazardous waste sites identified for possible long-term remedial action under the Comprehensive Environmental 

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Response, Compensation, and Liability Act (CERCLA). The list is based primarily on the score a site receives from the 

Environmental Protection Agency Hazard Ranking System. The Environmental Protection Agency is required to update the 

National Priorities List at least once a year. 

National Rural Electric Cooperative Association (NRECA): A national organization dedicated to representing the interests 

of cooperative electric utilities and the consumers theyserve. Members come from the 46 states that have an electric 

distribution cooperative. 

National Uranium Resource Evaluation (NURE): A program begun by the U.S. Atomic Energy Commission (AEC) in 1974 to 

make a comprehensive evaluation of U.S. uranium resources and continued through1983 by the AEC's successor 

agencies, the Energy Research and Development Administration (ERDA), and the Department of Energy (DOE).The NURE 

program included aerial radiometric and magnetic surveys, hydrogeochemical and stream sediment surveys, geologic 

drilling in selected areas, geophysical logging of selected bore holes, and geologic studies to identify and evaluate 

geologic environments favorable for uranium. 

Native gas: Gas in place at the time that a reservoir was converted to use as an underground storage reservoir in contrast 

to injected gas volumes. 

Native load (electric): The end-use customers that the Load-Serving Entity is obligated to serve. NERC definition 

Natural gas: Agaseous mixture of hydrocarbon compounds, the primary one being methane. 

Natural gas field facility: Afield facility designed to process natural gas produced from more than one lease for the 

purpose of recovering condensate from a stream of natural gas; however, some field facilities are designed to recover 

propane, normal butane, pentanes plus, etc., and to control the quality of natural gas to be marketed. 

Natural gas gross withdrawals: Full well-stream volume of produced natural gas, excluding condensate separated at the 

lease. 

Natural gas hydrates: Solid, crystalline, wax-like substances composed of water, methane, and usually a small amount of 

other gases, with the gases being trapped in the interstices of a water-ice lattice. Theyform beneath permafrost and on the 

ocean floor under conditions of moderately high pressure and at temperatures near the freezing point of water. 

Natural gas lease production: Gross withdrawals of natural gas minus gas production injected on the lease into 

producing reservoirs, vented, flared, used as fuel on the lease, and nonhydrocarbon gases removed in treating or 

processing operations on the lease. 

Natural Gas Liquids (NGL): Those hydrocarbons in natural gas that are separated from the gas as liquids through the 

process of absorption, condensation, adsorption, cooling in gas separators, gas processing, or gas cycling plants. 

Generally I gas liquids include natural gas plant liquids and lease condensate. 

Natural gas liquids production: The volume of natural gas liquids removed from natural gas in lease separators, f Id 

facilities, gas processing plants, or cycling plants during the report year. 

Natural gas marketed production: Gross withdrawals of natural gas from production reservoirs, less gas used for 

reservoir repressuring, nonhydrocarbon gases removed in treating and processing operations, and quantities vented and 

flared. 

Natural gas marketer: Acompanythat arranges purchases and sales of natural gas. Unlike pipeline companies or local 

distribution companies, a marketer does not own physical assets commonly used in the supplyof natural gas, such as 

pipelines or storage fields. A marketer maybe an affiliate of another company, such as a local distribution company, natural 

gas pipeline, or producer, but it operates independentlyof other segments of the company. In States with residential choice 

programs, marketers serve as alternative suppliers to residential users of natural gas, which is delivered by a local 

distribution company. 

Natural gas plant liquids: Those hydrocarbons in natural gas that are separated as liquids at natural gas processing 

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plants, f ling plants, and in some instances, field facilities. Lease condensate is excluded. Products 

obtained include liquefied petroleum gases (ethane, propane, and butanes), pentanes plus, and isopentane. Component 

products maybe fractionated or mixed. 

Natural Gas Policy Act of 1978 (NGPA): Signed into law on November 9, 1978, the NGPA is a framework for the regulation 

of most facets of the natural gas industry. 

Natural gas processing plant: Facilities designed to recover natural gas liquids from a stream of natural gas that mayor 

may not have passed through lease separators and/or field separation facilities. These facilities control the quality of the 

natural gas to be marketed. Cycling plants are classified as gas processing plants. 

Natural gas production: SeeDry natural gas production. 

Natural Gas Used for In I gas used to pressurize crude oil reservoirs in an attempt to increase oil recovery or 

in instances where there is no market for the natural gas. Natural gas used for injection is sometimes referred to as 

repressuring. 

Natural gas utility demand-side management (DSM) program sponsor: A DSM (demand-side management) program 

sponsored by a natural gas utility that suggests ways to increase the energy efficiency of buildings, to reduce energy costs, 

to change the usage patterns, or to promote the use of a different energy source. 

Natural gas, "dry": SeeDry natural gas. 

Natural gasoline: Aterm used in the gas processing industryto refer to a mixture of liquid hydrocarbons (mostly pentanes 

and heavier hydrocarbons) extracted from natural gas. It includes isopentane. 

Natural Gasoline and Isopentane: A mixture of hydrocarbons, mostly pentanes and heavier, extracted from natural gas, that 

meets vapor pressure, end-point, and other specifications for natural gasoline set by the Gas Processors Association. 

Includes isopentane which is a saturated branch-chain hydrocarbon, (C5H12), obtained byfractionation of natural gasoline 

or isomerization of normal pentane. 

Natural reservoir pressure: The energy within an oil or gas reservoir that causes the oil or gas to rise (unassisted by other 

forces) to the earth's surface when the reservoir is penetrated by an oil or gas well. The energy maybe the result of 

"dissolved gas drive," "gas cap drive," or "water drive." Regardless of the ty , the principle is the same: the energy 

of the gas or water, creating a natural pressure, forces the oil or gas to the well bore. 

Natural streamflow: The rate of flow of water past a given point of an uncontrolled stream or regulated streamflow adjusted 

to eliminate the effects of reservoir storage or upstream diversions at a set time interval. 

Natural uranium: Uranium with the U-235 isotope present at a concentration of 0.711 percent (by weight), that is, uranium 

with its isotopic content exactly as it is found in nature. 

Near-month contract for energy futures: The near-month contract, a term used in energyfutures and options trading and 

other transactions, is the active contract with the shortest time to maturity. It is the contract that will expire first (often, but not 

always, within the next month). The near month is also called the prompt month, the front month, the lead month, and the 

first nearby. 

NERC: SeeNorth American Electric Reliability Corporation. 

Net actual interchange (electric): The algebraic sum of all metered interchange over all interconnections between two 

physically Adjacent Balancing Authority Areas. NERC definition 

Net cell shipments: Represents the difference between cell shipments and cell purchases. 

Net electricity consumption: Consumption of electricity com puted as generation, plus imports, minus exports, minus 

transmission and distribution losses. 

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Net energy for load: Net generation of main generating units that are system-owned or system-operated, plus energy 

receipts minus energy deliveries. 

Net energy for load (electric): Net Balancing Authority Area generation, plus energy received from other Balancing Authority 

Areas, less energy delivered to Balancing AuthorityAreas through interchange. It includes Balancing AuthorityArea losses 

but excludes energy required for storage at energy storage facilities.NERC definition 

Net energy for system: The sum of energy an electric utility needs to satisfy their service areas, including full and partial 

requirements consumers. 

Net generation: The amount of gross generation less the electrical energy consumed at the generating station(s) for 

station service or auxiliaries. Note: Electricity required for pumping at pumped-storage plants is regarded as electricityfor 

station service and is deducted from gross generation. 

Net head: The gross head minus all hydraulic losses except those chargeable to the turbine. 

Net income: Operating income plus other income and extraordinary income less operating expenses, taxes, interest 

charges, other deductions, and extraordinary deductions. 

Net interstate flow of electricity: The difference between the sum of electricity sales and losses within a state and the total 

amount of electricity generated within that state. A positive number indicates that more electricity (including associated 

losses) came into the state than went out of the state during the year; conversely, a negative number indicates that more 

electricity (including associated losses) went out of the state than came into the state. 

Net module shipments: Represents the difference between module shipments and module purchases. When exported, 

incomplete modules and unencapsulated cells are also included. 

Net operable capacity: Total owned capacity less in operable capacity. 

Net photovoltaic module shipment: The difference between photovoltaic module shipments and photovoltaic module 

purchases. 

Net profits interest: A contractual arrangement under which the beneficiary, in exchange for consideration paid, receives a 

stated percentage of the net profits. That type of arrangement is considered a nonoperating interest, as distinguished from 

a working interest, because it does not involve the rights and obligations of operating a mineral property (costs of 

exploration, development, and operation). The net profits interest does not bear any part of net losses. 

Net Receipts: The difference between total movements into and total movements out of each PAD District by pipeline, 

tanker, and barge. 

Net summer capacity: The maximum output, commonly expressed in megawatts (M ), that generating equipment can 

supplyto system load, as demonstrated bya multi-hour test, at the time of summer peak demand (period of June 1 through 

September 30.) This output reflects a reduction in capacity due to electricity use for station service or auxiliaries. 

Net winter capacity: The maximum output, commonly expressed in megawatts (MW), that generating equipment can 

supply to system load, as demonstrated bya multi-hour test, at the time of peak winter demand (period of December 1 

through February 28). This output reflects a reduction in capacity due to electricity use for station service or auxiliaries. 

Netback purchase: Refers to a crude oil purchase agreement wherein the price paid for the crude is determined bysales 

prices of the types of products that are derivable from that crude as well as other considerations (e.g., transportation and 

processing costs). Typically, the price is calculated based on product prices extant on or near the cargo's date of 

im portation. 

New field: Afield discovered during the report year. 

New field discoveries: The volumes of proved reserves of crude oil, natural gas, and/or natural gas liquids discovered in 

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new fields during the report year. 

New reservoir: A reservoir discovered during the report year. 

NGL: See Natural gas liquids. 

NGPA: See Natural Gas PolicyAct of 1978. 

NGPL: Natural Gas Plant Liquids 

NGV: Natural Gas Vehicle 

Nitrogen dioxide: A com pound of nitrogen and oxygen formed by the oxidation of nitric oxide (NO) which is produced by the 

combustion of solid fuels. 

Nitrogen oxides (NOx): Compounds of nitrogen and oxygen produced bythe burning of fossil fuels. 

Nitrous oxide (N20): A colorless gas, naturallyoccurring in the atmosphere. Nitrous wade has a 100-year Global Warming 

Potential of 310. 

No. 1 diesel fuel: Alight distillate fuel oil that has a distillation tern perature of 550 degrees Fahrenheit at the 90-percent 

recovery point and meets the specifications defined in ASTM Specification D 975. It is used in high speed diesel engines 

generally operated under frequent speed and load changes, such as those in city buses and similar vehicles. See No. 1 

distillate. 

No. 1 distillate: Alight petroleum distillate that can be used as either a diesel fuel (see No. 1 diesel fuel) or a fuel oil (see 

No. 1 fuel oil). 

No. 1 fuel oil: Alight distillate fuel oil that has distillation temperatures of 400 degrees Fahrenheit at the 10-percent recovery 

point and 550 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM 

Specification D 396. It is used primarily as fuel for portable outdoor stoves and portable outdoor heaters. See No. 1 

Distillate. 

No. 2 diesel fuel: A distillate fuel oil that has a distillation temperature of 640 degrees Fahrenheit at the 90-percent recovery 

point and meets the specifications defined in ASTM Specification D 975. It is used in high-speed diesel engines that are 

generally operated under uniform speed and load conditions, such as those in railroad locomotives, trucks, and 

automobiles. See No. 2 Distillate. 

No. 2 distillate: A petroleum distillate that can be used as either a diesel fuel (see No. 2 diesel fuel) or a fuel oil (see No. 2 

fuel oil). 

No. 2 fuel oil (heating oil): A distillate fuel oil that has distillation temperatures of 400 degrees Fahrenheit at the 10-percent 

recovery point and 640 degrees Fahrenheit at the 90-percent recovery point and meets the specifications defined in ASTM 

Specification D 396. It is used in atomizing type burners for domestic heating or for moderate capacity commercial/industrial 

burner units. See No. 2 Distillate. 

No. 2 fuel oil and No. 2 diesel sold to consumers for all other end uses: Those consumers who purchase fuel oil or diesel 

fI for their own use including commercial/institutional buildings (including apartment buildings), manufacturing and 

nonmanufacturing establishments, farms (including farm houses), motor vehicles, commercial or private boats, military, 

governments, electric utilities, railroads, construction, logging or any other nonresidential end-use purpose. 

No. 2 fuel oil sold to private homes for heating: Private household customers who purchase fuel oil for the specific 

purpose of heating their home, water heating, cooking, etc., excluding farm houses, farming and apartment buildings. 

No. 4 fuel oil: A distillate fuel oil made by blending distillate fuel oil and residual f I oil stocks. It conforms with ASTM 

Specification D 396 or Federal Specification W-F-815C and is used extensively in industrial plants and in commercial 

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burner installations that are not equipped with preheating facilities. It also includes No. 4 diesel fuel used for low- and 

medium-speed diesel engines and conforms to ASTM Specification D 975. 

No. 5 and no. 6 fuel oil sold directly to the ultimate consumer: Includes ships, mines, smelters, manufacturing plants, 

electric utilities, drilling, railroad. 

No. 5 and no. 6 fuel oil sold to refiners or other dealers who will resale the product: Includes all volumes of No. 5 and 

No. 6 fuel oil purchased by a trade or business with the intent of reselling the product to the ultimate consumers. 

Nox: SeeNitrogen oxides 

NOAA: National Oceanic and Atmospheric Administration. 

NOAA division: One of the 345 weather divisions designated bythe National Oceanic and Atmospheric Administration 

(NOM) encompassing the 48 contiguous states. These divisions usually follow county borders to encompass counties 

with similar weather conditions. The NOAA division does not follow county borders when weather conditions vary 

considerably within a county such is likely to happen when the county borders the ocean or contains high mountains. A 

state contains an average of seven NOAA divisions; a NOAA division contains an average of nine counties. 

Noload loss: Power and energy lost by an electric system when not operating under demand. 

Nominal dollars: A m easure used to express nominal price. 

Nominal price: The price paid for a product or service at the time of the transaction. Nominal prices are those that have not 

been adjusted to remove the effect of changes in the purchasing power of the dollar; they reflect buying power in the year in 

which the transaction occurred. 

Non-biomass waste: Material of non-biological origin that is a byproduct or a discarded product. "Non-biomass waste" 

includes municipal solid waste from non-biogenic sources, such as plastics, and tire-derived fuels. 

Nonassociated natural gas: Natural gas that is not in contact with significant quantities of crude oil in the reservoir. See 

natural gas. 

Nonattainment area: Any area that does not meet the national primary or secondary ambient air qualitystandard 

established by the Environmental Protection Agencyfor designated pollutants, such as carbon monoxide and ozone. 

Nonbranded product: Any refined petroleum product that is not a branded product. 

Noncoincident demand: Sum of two or more demands on individual systems that do not occur in the same demand 

interval. 

Noncoincidental peak load: The sum of two or more peak loads on individual systems that do not occur in the same time 

interval. Meaningful only when considering loads within a limited period of time, such as a day, week, month, a heating or 

cooling season, and usually for not more than 1 year. 

Nonconventional plant (uranium): Afacility engineered and built principallyfor processing of uraniferous solutions that are 

produced during in situ leach mining, from heap leaching, or in the manufacture of other commodities, and the recovery, by 

chemical treatment in the plant's circuits, of uranium from the processing solutions. 

Nondedicated vehicle: A motor vehicle capable of operating on an alternative fuel and /or on either gasoline or diesel. 

Nonfirm power: Power or power-producing capacity supplied or available under a commitment having limited or no 

assured availability. 

Nonfuel components: Components that are not associated with a particular fuel. These include, but are not limited to, 

control spiders, burnable poison rod assemblies, control rod elements, thimble plugs, fission chambers, primary and 

secondary neutron sources, and BWR (boiling water reactor) channels. 

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Nonfuel use (of energy): Use of energy as feedstock or raw material input. 

Nonfungible product: A gasoline blend or blendstock that cannot be shipped via existing petroleum product distribution 

systems because of incompatibility problems. Gasoline/ethanol blends, for example, are contaminated bywater that is 

typically present in petroleum product distribution systems. 

Nonhydrocarbon gases: Typical nonhydrocarbon gases that may be present in reservoir natural gas, such as 

carbondioxide, helium, hydrogen sulfide, and nitrogen. 

Nonmethane volatile organic compounds (NMVOC): Organic compounds, other than methane, that participate in 

atmospheric photochemical reactions. 

Nonoperating interest: Any mineral lease interest (e.g., royalt , production payment, net profits interest) that does not 

involve the rights and obligations of operating a mineral property. 

Nonproducing reservoir: Reservoir in which oil and/or gas proved reserves have been identified, but which did not produce 

during the report year to the owned or contracted interest of the reporting company regardless of the availability and/or 

operation of production, gathering, or transportation facilities. 

Nonrenewable fuels: Fuels that cannot be easily made or "renewed," such as oil, natural gas, and coal. 

Nonrequirements consumer: Awholesale consumer (unlike a full or partial requirements consumer) that purchases 

economic or coordination power to supplement their own or another system's energy needs. 

Nonresidential building: A building used for some purpose other than residential. Nonresidential buildings comprise three 

groups commercial, manufacturing/industrial, and agricultural. 

Nonroad alternative fuel vehicle (nonroad AFV): An alternative fuel vehicle designed for off-road operation and use for 

surface/air transportation, industrial, or commercial purposes. Nonroad AFVs include forklifts and other industrial vehicles, 

rail locomotives, self-propelled electric rail cars, aircraft, airport service vehicles, construction vehicles, agricultural vehicles, 

and marine vessels. Recreational A (golf carts, snow mobiles, pleasure watercraft, etc.) are excluded from the 

definition. 

Nonspinning reserve: The generating capacity not currently running but capable of being connected to the bus and load 

within a specified time. 

Nonutility generation: Electric generation by end-users, or small power producers under the Public Utility Regulatory 

Policies Act, to supply electric power for industrial, commercial, andmilitary operations, or sales to electric utilities. 

Nonutility power producer: A corporation, person, agency, authority, or other legal entity or instrumentality that owns or 

operates facilities for electric generation and is not an electric utility. Nonutility power producers include qualifying 

cogenerators, qualifying small power producers, and other nonutility generators (including independent power producers). 

Non-utility power producers are without a designated franchised service area and do not file forms listed in the Code of 

Federal Regulations, Title 18, Part 141 

NOPR: Notice of Proposed Rulemaking 

Normal butane (C ): A normally gaseous straight chain hydrocarbon that is a colorless paraffinic gas which boils at a 

temperature of 31.1 degrees Fahrenheit. 

North American Electric Reliability Corporation (NERC): A nonprofit corporation formed in 2006 as the successor to the 

North American Electric ReliabilityCouncil established to develop and maintain mandatory reliabilitystandards for the bulk 

electric system, with the fundamental goal of maintaining and improving the reliability of that system. NERC consists of 

regional reliability entities covering the interconnected power regions of the contiguous United States, Canada, and Mexico. 

See theNorth American Electric Reliability Corporation (NERC) Regions. 

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North American Industry Classification System (NAICS): Anew classification scheme, developed by the Off f 

Management and Budget to replace the Standard Industrial Classification (SIC) System, that categorizes establishments 

according to the types of production processes they primarily use. 

NRECA: SeeNational Rural Electric Cooperative Association 

Nuclear electric power (nuclear power): Electricity generated by the use of the thermal energy released from the fission of 

nuclear fuel in a reactor. 

Nuclear fuel: Fissionable materials that have been enriched to such a composition that, when placed in a nuclear reactor, 

will support a self-sustaining fission chain reaction, producing heat in a controlled manner for process use. 

Nuclear reactor: An apparatus in which a nuclear fission chain reaction can be initiated, controlled, and sustained at a 

specific rate. A reactor includes fuel (fissionable material), moderating material to control the rate of fission, a heavy-walled 

pressure vessel to house reactor components, shielding to protect personnel, a system to conduct heat away from the 

reactor, and instrumentation for monitoring and controlling the reactor's systems. 

NUG: Nonutility Generator 

Number of mines: The number of mines, or mines collocated with preparation plants or tipples, located in a particular 

geographic area (State or region). If a mine is mining coal across two counties within a State, or across two States, then it is 

counted as two operations. This is done so that EIA can separate production by State and county. 

Number of mining operations: The number of mining operations includes preparation plants with greater than 5,000 total 

direct labor hours. Mining operations that consist of a mine and preparation plant, or a preparation plant only, will be 

counted as two operations if the preparation plant processes both underground and surface coal. Excluded are silt, culm, 

refuse bank, slurry dam, and dredge operations except for Pennsylvania anthracite. Excludes mines producing less than 

10,000 short tons of coal during the year. 

NURE: SeeNational Uranium Resource Evaluation 

NYMEX: New York Mercantile Exchange 

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Glossary 

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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

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O&M: Operation and Maintenance. 

03: SeeOzone. 

Occupancy sensors: These are also known as "ultrasonic switchers." When movement is detected, the lights are turned 

on and remain on as long as there is movement in the room. 

Ocean energy systems: Energy conversion technologies that harness the energy in tides, waves, and thermal gradients in 

the oceans. 

Ocean thermal energy conversion (OTEC): The process or technologies for producing energy by harnessing the 

temperature differences (thermal gradients) between ocean surface waters and that of ocean depths. Warm surface water 

is pumped through an evaporator containing a working fluid in a closed Rankine-cycle system. The vaporized fluid drives a 

turbine/generator. 

OCS: SeeOuter Continental Shelf. 

Octane: Aflammable liquid hydrocarbon found in petroleum. Used as a standard to measure the anti-knock properties of 

motor fuel. 

Octane rating: A number used to indicate gasoline's antiknock performance in motor vehicle engines. The two recognized 

laboratory engine test methods for determining the antiknock rating, i.e., octane rating, of gasolines are the Research 

method and the Motor method. To provide a single number as guidance to the consumer, the antiknock index (R + M)/2, 

which is the average of the Research and Motor octane numbers, was developed. 

OECD: SeeOrganization for Economic Cooperation and Development. 

OEM: SeeOriginal Equipment Manufacturer(s). 

Off peak: Period of relatively low system demand. These periods often occur in daily, weekly, and seasonal patterns; these 

off-peak periods differ for each individual electric utility. 

Off peak gas: Gas that is to be delivered and taken on demand when demand is not at its peak. 

Off-highway use: Includes petroleum products sales for use in: 

1. Construction. Construction equipment including earth moving equipment, cranes, stationary generators, air 

compressors, etc. 

2. Other. Sales for off-highway uses other than construction. Sales for logging are included in this category. Volumes 

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for off-highway use bythe agriculture industr ted under "Farm Use" (which includes sales for use in 

tractors, irrigation pumps, other agricultural machinery, etc.) 

Off-hours equipment reduction: Aconservation feature where there is a change in the temperature setting or reduction in 

the use of heating, cooling, domestic hot water heating, lighting or anyother equipment either manuallyor automatically. 

Off-system: Any point not on or directly interconnected with a transportation, storage, and/or distribution system operated 

by a natural gas company within a state. 

Offshore: That geographic area that lies seaward of the coastline. In general, the coastline is the line of ordinary low water 

along with that portion of the coast that is in direct contact with the open sea or the line marking the seaward limit of inland 

water. If a state agency uses a different basis for classifying onshore and offshore areas, the state classification should be 

used (e.g., Cook Inlet in Alaska is classified as offshore; for Louisiana, the coastline is defined as the Chapman Line, as 

modified bysubsequent adjudication). 

Offshore reserves and production: Unless otherwise dedicated, reserves and production that are in either state or 

Federal domains, located seaward of the coastline. 

Offsite-produced energy for heat, power, and electricity generation: This measure of energy consumption, which is 

equivalent to purchased energy includes energy produced off-site and consumed onsite. It excludes energy produced and 

consumed onsite, energy used as raw material input, and electricity losses. 

Offsystem (natural gas): Natural gas that is transported to the end user by the company making final delivery of the gas to 

the end user. The end user purchases the gas from another company, such as a producer or marketer, not from the 

delivering corn pany (typically a local distribution company or a pipeline company). 

Ohm: A measure of the electrical resistance of a material equal to the resistance of a circuit in which the potential 

difference of 1 volt produces a current of 1 ampere. 

Ohm's Law: In a given electrical circuit, the amount of current in amperes is equal to the pressure in volts divided bythe 

resistance, in ohms. The principle is named after the German scientist Georg Simon Ohm. 

Oil: A m bdure of hydrocarbons usually existing in the liquid state in natural underground pools or reservoirs. Gas is often 

found in association with oil. Also seePetroleum. 

Oil company use: Includes sales to drilling companies, pipelines or other related oil companies not engaged in the selling 

of petroleum products. Includes fuel oil that was purchased or produced and used by com panyfacilities for the operation of 

drilling equipment, other field or refinery operations, and space heating at petroleum refineries, pipeline companies, and 

oil-drilling companies. Oil used to bunker vessels is counted under vessel bunkering. Sales to other oil companies for field 

use are included, but sales for use as refinery charging stocks are excluded. 

Oil reservoir: An underground pool of liquid consisting of hydrocarbons, sulf , oxygen, and nitrogen trapped within a 

geological formation and protected from evaporation bythe overlying mineral strata. 

Oil shale: Asedimentary rock containing kerogen, a solid organic material. 

Oil stocks: Oil stocks include crude oil (including strategic reserves), unfinished oils, natural gas plant liquids, and refined 

petroleum products. 

Oil well: Awell completed for the production of crude oil f least one oil zone or reservoir. 

Oil well (casing head) gas: Associated and dissolved gas produced along with crude oil f I completions. 

Old field: Afield discovered prior to the report year. 

Old reservoir: A reservoir discovered prior to the report year. 

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On-highway use (diesel): Includes sales for use in motor vehicles. Volumes used by com panies in the marketing and 

distribution of petroleum products are also included. 

On-peak: Periods of relatively high system demand. These periods often occur in daily, weekly, and seasonal patterns; 

these on-peak periods differ for each individual electric utility. 

On-system: Any point on or directly interconnected with a transportation, storage, or distribution system operated by a 

natural gas company. 

On-system sales: Sales to customers where the delivery point is a point on, or directly interconnected with, a 

transportation, storage, and/or distribution system operated bythe reporting company. 

One sun: Natural solar insulation falling on an object without concentration or diffusion of the solar rays. 

One-time fee: The fee assessed a nuclear utility for spent nuclear fuel (SNF) or solidified high-level radioactive waste 

derived from SNF, which fuel was used to generate electricity in a civilian nuclear power reactor prior to April 7, 1983, and 

which isassessed by apply -wide average dollar-per-kilogram charges to four distinct ranges of fuel burn up so 

that equivalent to an industry-wide average charge of 1.0 mill per kilowatthour. 

Onsite transportation: The direct nonprocess end use that includes energy used in vehicles and transportation equipment 

that primarily consume energywithin the boundaries of the establishment. Energy used in vehicles that are found primarily 

offsite, such as deliverytrucks, is not measured bythe MECS (an ElAsurvey). 

Onsystem (natural gas): Natural gas that is sold (and transported) to the end user by the company making final delivery of 

the gas to the end user. Companies that make final delivery of natural gas are typically local distribution companies or 

pipeline companies. 

OPEC: SeeOrganization of Petroleum Exporting Countries. 

OPEC (Organization of the Petroleum Exporting Countries): An intergovernmental organization whose stated objective is 

to "coordinate and unifythe petroleum policies of member countries." It was created at the Baghdad Conference on 

September 10-14, 1960. Current members (with years of membership) include: 

• Algeria (1969-present) 

• Angola (2007-present) 

• Ecuador (1973-1992 and 2007-present) 

• Iran (1960-present) 

• Iraq (1960-present) 

• Kuwait (1960-present) 

• Libya (1962-present) 

• Nigeria (1971-present) 

• Qatar (1961-present) 

• Saudi Arabia (1960-present) 

• United Arab Emirates (1967-present) and 

• Venezuela (1960-present) 

Countries no longer members of OPEC include: 

• Gabon (1975-1994) 

• Indonesia (1962-2008) 

Open access: A regulatory mandate to allow others to use a utility's transmission and distribution facilities to move bulk 

power from one point to another on a non discriminatory basis for a cost-based fee. 

Open access (electric): Federal Energy Regulatory Commission Order No. 888 requires public utilities to provide nondiscriminatorytransmission service over their transmission facilities to third parties to move bulk power from one point to 

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another on a nondiscriminatory basis for a cost-based fee. Order 890 expanded Open Access to cover the methodology for 

calculating available transmission transfer capability is that opened a coordinated transmission planning 

processes; standardization of energy and generation imbalance charges; and other reforms regarding the designation and 

undesignation of transmission network resources. SeeNERC definition. 

Open access transmission tariff (electric): Electronic transmission tariff accepted by the U.S. Federal Energy Regulatory 

Commission requiring the Transmission Service Provider to furnish to all shippers with non-discriminating service 

comparable to that provided by Transmission Owners to themselves. SeeNERC definition. 

Open market coal: Coal is sold in the open market, i.e., coal sold to companies other than the reporting companys parent 

company or an operating subsidiary of the parent company. 

Open refrigeration unit: Refrigeration in cabinets (units) without covers or with flexible covers made of plastic or some 

other material, hung in strips or curtains (fringed material, usually plastic, that push aside like a bead curtain). Flexible 

covers stop the flow of warm air into the refrigerated space. 

Operable capacity: The amount of capacity that, at the beginning of the period, is in operation; not in operation and not 

under active repair, but capable of being placed in operation within 30 days; or not in operation but under active repair that 

can be completed within 90 days. Operable capacity is the sum of the operating and idle capacity and is measured in 

barrels per calendar day or barrels per stream day. 

Operable generators/units: Electric generators or generating units that are available to provide power to the grid or 

generating units that have been providing power to the grid but are temporarily shut down. This includes units in standby 

status, units out of service for an indefinite period, and new units that have their construction complete and are ready to 

provide test generation. A nuclear unit is operable once it receives its Full Power Operating License. 

Operable nuclear unit (foreign): A nuclear generating unit outside the United States that generates electricityfor a grid. 

Operable nuclear unit (U.S.): A U.S. nuclear generating unit that has completed low-power testing and is in possession of 

a full-power operating license issued bythe Nuclear Regulatory Commission. 

Operable refineries: Refineries that were in one of the following three categories at the beginning of a given year in 

operation; not in operation and not under active repair, but capable of being placed into operation within 30 days; or not in 

operation, but under active repair that could be completed within 90 days. 

Operable unit: A unit available to provide electric power to the grid. See definition foroperating unit. 

Operable utilization rate: Represents the use of the atmospheric crude oil distillation units. The rate is calculated by 

dividing the gross input to these units by the operable refining capacity of the units. 

Operated: Exercised management responsibilityfor the day-to-day operations of natural gas production, gathering, 

treating, processing, transportation, storage, and/or distribution facilities and/or a synthetic natural gas plant. 

Operating capacity: The component of operable capacity that is in operation at the beginning of the period. 

Operating day: A normal business day. Days when a company conducts business due to emergencies or other 

unexpected events are not included. 

Operating expenses: Segment expenses related both to revenue from sales to unaffiliated customers and revenue from 

intersegment sales or transfers, excluding loss on disposition of property, plant, and equipment; interest expenses and 

financial charges; foreign currencytranslation effects; minority interest; and income taxes. 

Operating income: Operating revenues less operating expenses. Excludes items of other revenue and expense, such as 

equity in earnings of unconsolidated affiliates, dividends, interest income and expense, income taxes, extraordinary items, 

and cumulative effects of accounting changes. 

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Operating revenues: Segment revenues both from sales to unaffiliated customers (i.e., revenue from customers outside 

the enterprise as reported in the companys consolidated income statement) and from intersegment sales or transfers, if 

any, of product and services similar to those sold to unaffiliated customers, excluding equity in earnings of unconsolidated 

affiliates; dividend and interest income; gain on disposition of property, plant, and equipment; and foreign currency 

translation effects. 

Operating subsidiary: Company that operates a coal mining operation and is owned byanother corn pany (i.e., the parent 

company). 

Operating unit: A unit that is in operation at the beginning of the reporting period. 

Operating utilization rate: Represents the use of the atmospheric crude oil distillation units. The rate is calculated by 

dividing the gross input to these units by the operating refining capacity of the units. 

Operator, gas plant: The person responsible for the management and day-to-day operation of one or more natural gas 

processing plants as of December 31 of the report year. The operator is generally a working-interest owner or a company 

under contract to the working-interest owner(s). Plants shut down during the report year are also to be considered 

"operated" as of December 31 

Operator, oil and/or gas well: The person responsible for the management and day-to-day operation of one or more crude 

oil and/or natural gas wells as of December 31 of the report year. The operator is generally a working-interest owner or a 

company under contract to the working-interest owner(s). Wells included are those that have proved reserves of crude oil, 

natural gas, and/or lease condensate in the reservoirs associated with them, whether or not they are producing. Wells 

abandoned during the report year are also to be considered "operated" as of December 31. 

OPRG: Oxygenated fuels Program Reformulated Gasoline. 

Optional delivery commitment: A provision to allow the conditional purchase or sale of a specific quantity of material in 

addition to the firm quantity in the contract. 

Order: A ruling issued by a utility commission granting or denying an application in whole or in part. The order explains the 

basis for the decision, noting any dispute with the factual assertions of the applicant. Also applied to a final regulation of a 

utility com m iss ion. 

Organic content: The share of a substance that is of animal or plant origin. 

Organic waste: Waste material of animal or plant origin. 

Organization for Economic Cooperation and Development (OECD): An international organization helping governments 

tackle the economic, social and governance challenges of a globalized economy. Its membership comprises about 30 

member countries. With active relationships with some 70 other countries, non-governmental organizations (NGOs) and 

civil society, it has a global reach. For details about the organization, visithttp://www.oecd.org. 

Organization of the Petroleum Exporting Countries (OPEC): Organization of Petroleum Exporting Countries. 

Original cost: The initial amount of m oney spent to acquire an asset. It is equal to the price paid, or present value of the 

liability incurred, or fair value of stock issued, plus normal incidental costs necessaryto put the asset into its initial use. 

Original equipment manufacturer (OEM): A com pany that provides the original design and materials for manufacture and 

engages in the assembly of vehicles. The OEM is directly responsible for manufacturing, marketing, and providing 

warranties for the finished product. 

Original equipment manufacturer vehicle: A vehicle produced and marketed by an original equipment manufacturer 

(OEM), including gasoline and diesel vehicles as well as alternative-f I vehicles. A vehicle manufactured by an OEM but 

converted to an alternative-f I vehicle before its initial delivery to an end-user (for example, through a contract between a 

conversion company and the OEM) is considered to be an OEM vehicle as long as that vehicle is still covered under the 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

OEM's warranty. 

OTEC: SeeOcean Thermal Energy Conversion. 

Other: The "other" category is defined as representing electricity consumers not elsewhere classified. This category 

includes public street and highway lighting service, public authority service to public authorities, railroad and railway service, 

and interdepartmental services. 

Other capital costs: Costs for items or activities not included elsewhere under capital-cost tabulations, such as for and 

decommissioning, dismantling, and reclamation. 

Other demand-side management (DSM) assistance programs: A DSM program assistance that includes alternative-rate, 

fuel-switching, and any other DSM assistance programs that are offered to consumers to encourage their participation in 

DSM programs. 

Other end users: For motor gasoline, all direct sales to end users other than those made through company outlets. For 

No. 2 distillate, all direct sales to end users other than residential, commercial/institutional, industrial sales, and sales 

through corn pany outlets. Included in the "other end users" category are sales to utilities and agricultural users. 

Other energy operations: Energy operations not included under Petroleum or Coal. "Other energy" includes nuclear, oil 

shale, tar sands, coal liquefaction and gasification, geothermal, solar, and other forms of on conventional energy. 

Other finished: Motor gasoline not included in the oxygenated or reformulated gasoline categories. 

Other gas: Includes manufactured gas, coke-oven gas, blast-f , and refinerygas. Manufactured gas is obtained 

by distillation of coal, by the thermal decomposition of oil, or by the reaction of steam passing through a bed of heated coal 

or coke. 

Other generation: Electricity originating from these sources biomass, fuel cells, geothermal heat, solar power, waste, 

wind, and wood. 

Other industrial plant: Industrial users, not including coke plants, engaged in the mechanical or chemical transformation 

of materials or substances into new products (manufacturing); and companies engaged in the agriculture, mining, or 

construction industries. 

Other load management: Demand-Side Management (DSM) program other than Direct Load Control and Interruptible 

Load that limits or shifts peak load from on-peak to off-peak time periods. It includes technologies that primarily shift all or 

part of a load from one time-of-day to another and secondarily may have an impact on energy consumption. Examples 

include space heating and water heating storage systems, cool storage systems, and load limiting devices in energy 

management systems. This category also includes programs that aggressively promote time-of-use rates and other 

innovative rates such as real time pricing. These rates are intended to reduce consumer bills and shift hours of operation of 

equipment from on-peak to off-peak periods through the application of time-differentiated rates. 

Other oils equal to or greater than 401 degrees Fahrenheit: Oils with a boiling range equal to or greater than 401 degrees 

Fahrenheit that are intended for use as a petrochemical feedstock. 

Other operating costs: Costs for other items or activities not included elsewhere in operating-cost tabulations, but 

required to support the calculation of a cutoff grade for ore reserves estimation. 

Other oxygenates: Other aliphatic alcohols and aliphatic ethers intended for motor gasoline blending (e.g., isopropylether 

(IPE) or n-propanol). 

Other power producers: Independent power producers that generate electricity and cogeneration plants that are not 

included in the other industrial, coke and commercial sectors. 

Other refiners: Refiners with a total refinery capacity in the United States and its possessions of less than 275,000 barrels 

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per day as of January 1, 1982. 

Other service to public authorities: Electricity supplied to municipalities, divisions or agencies of state or Federal 

governments, under special contracts or agreements or service classifications applicable onlyto public authorities. 

Other single-unit truck: A motor vehicle consisting primarily of a single motorized device with more than two axles or more 

than four tires. 

Other supply contracts: Any contracted gas supply other than owned reserves, producer-contracted reserves, and 

interstate pipeline purchases that are used for acts and services for which the company has received certificate 

authorization from FERC. Purchases from intrastate pipelines pursuant to Section 311(b) of the NGPA of 1978 are included 

with other supply contracts. 

Other trucks/v ,500 lbs GVW. 

Other unavailable capability: Net capability of main generating units that are unavailable for load for reasons other than 

full-forced outage or scheduled maintenance. Legal restrictions or other causes make these units unavailable. 

Outage: The period during which a generating unit, transmission line, or other facility is out of service. 

Outer Continental Shelf: Offshore Federal domain. 

Output: The amount of power or energy produced by a generating unit, station, or system. 

Oven: An appliance that is an enclosed corn partment supplied with heat and used for cooking food. Toaster ovens are not 

considered ovens. The range stove top or burners and the oven are considered two separate appliances, although they are 

often purchased as one appliance. 

Overburden: Any material, consolidated or unconsolidated, that overlies a coal deposit. 

Overburden ratio: Overburden ratio refers to the amount of overburden that must be removed to excavate a given quantity of 

coal. It is commonly expressed in cubic yards per ton of coal, but is sometimes expressed as a ratio comparing the 

thickness of the overburden with the thickness of the coalbed. 

Overriding royalty: A royalt It f the working interest; it is, therefore, 

limited in its duration to the life of the lease under which it is created. 

Owned reserves: Any reserve of natural gas that the reporting company owns as a result of oil and gas leases, fee-mineral 

ownership, royalt lease or royalt 

. Company-owned recoverable natural gas in underground storage is classified as owned reserves. 

Owned/rented: (As used in EIA's consumption surveys.) The relationship of a housing unit's occupants to the structure 

itself, not the land on which the structure is located. "Owned" means the owner or co-owner is a member of the household 

and the housing unit is either fully paid for or mortgaged. A household is classified "rented" even if the rent is paid by 

someone not living in the unit. "Rent-f 

. Such units are usually provided in exchange for services rendered or as an allowance or favor from a relative or 

friend not living in the unit. Unless shown separately, rent-f Ids are grouped with rented households. 

Owner occupied: (As used in EIA's consumption surveys.) Having the owner or the owner's business represented at the 

site. A building is considered owner occupied if an employee or representative of the owner (such as a building engineer or 

building manager) maintains office space in the building. Similarly, a chain store is considered owner occupied even 

though the actual owner may not be in the building but headquartered elsewhere. Other examples of the owner's business 

occupying a building include State-owned university buildings, elementaryand secondaryschools owned bya public 

school district, and a post office where the building is owned bythe U.S. Postal Service. 

Owners equity: Interest of the owners in the assets of the business represented by capital contributions and retained 

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earnings. 

Ownership: (See Owned/rented.) 

Ownership of building: (As used in EIA's consumption surveys.) The individual, agency, or organization that owns the 

building. For certain EIA consum ption surveys, building ownership is grouped into the following categories Federal, State, 

or local government agency; a privately owned utility company, a church, synagogue, or other religious group; or any other 

type of individual or group. 

Oxidize: To chemicallytransform a substance by com bining it with oxygen. 

Oxygenated gasoline: Finished motor gasoline, other than reformulated gasoline, having an oxygen content of 2.7percent 

or higher byweight and required bythe U.S. Envtal Protection Agency (EPA) to be sold in areas designated by EPA 

as carbon monoxide (CO) nonattainment areas. See Nonattainment area. 

Note: Oxygenated gasoline excludes oxygenated fuels program reformulated gasoline (OPRG) and reformulated gasoline 

blendstock for oxygenate blending (RBOB). Data on gasohol that has at least 2.7 percent oxygen, by weight, and is intended 

for sale inside CO nonattainment areas are included in data on oxygenated gasoline. Other data on gasohol (for use 

outside of nonattainment areas) are included in data on conventional gasoline. 

Oxygenated gasoline (includes Gasohol): Finished motor gasoline, other than reformulated gasoline, having an oxygen 

content of 1.8 percent or higher byweight. This includes gasohol irrespective of where it is consumed. 

Note: Oxygenated gasoline excludes oxygenated fuels program reformulated gasoline (OPRG) and reformulated gasoline 

blendstock for oxygenate blending (RBOB). 

Oxygenates: Substances which, when added to gasoline, increase the amount of oxygen in that gasoline blend. Fuel 

ethanol, Methyl Tertiary Butyl Ether (MTBE), Ethyl Tertiary Butyl Ether (ETBE), and methanol are common oxygenates. 

Ozone: A molecule made up of three atoms of oxygen. Occurs naturally in the stratosphere and provides a protective layer 

shielding the Earth from harmful ultraviolet radiation. In the troposphere, it is a chemical oxidant, a greenhouse gas, and a 

major component of photochemical smog. 

Ozone precursors: Chemical compounds, such as carbon monoxide, methane, non methane hydrocarbons, and nitrogen 

oxides, which in the presence of solar radiation react with other chemical compounds to form ozone. 

ABCDEFGHIJKLMNOPQRSTUVWXYZ 

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U.S. Energy Information 

Administration 

Glossary 

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Search glossary terms: 

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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

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Packaged air conditioning units: Usually mounted on the roof or on a slab beside the building. (These are known as selfcontained units, or Direct Expansion (DX). Theycontain air conditioning equipment as well as fans, and mayor may not 

include heating equipment.) These are self-contained units that contain the equipment that generates cool air and the 

equipment that distributes the cooled air. These units commonly consume natural gas or electricity. The units are mounted 

on the rooftop, exposed to the elements. They typically blow cool air into the building through ductwork, but other types of 

distribution systems mayexist. The units usuallyserve more than one room. There are often several units on the roof of a 

single building. Also known as Packaged Terminal Air Conditioners (PTAC). These packaged units are often constructed as 

a single unit for heating and for cooling. 

Packaged units: Units built and assembled at a factory and installed as a self-contained unit to heat or cool all or portions 

of a building. Packaged units are in contrast to engineer-specified units built up from individual components for use in a 

given building. Packaged Units can applyto heating equipment, cooling equipment, or combined heating and cooling 

equipment. Some ty lectric packaged units are also called "Direct Expansion" or DX units. 

PAD Districts or PADD: SeePetroleum Administration for Defense Districts. 

Parabolic dish: A high-tennperature (above 180 degrees Fahrenheit) solar thermal concentrator, generally bowl-shaped, 

with two-axis tracking. 

Parabolic trough: A high-tern perature (above 180 degrees Fahrenheit) solar thermal concentrator with the capacity for 

tracking the sun using one axis of rotation. 

Paraffin (oil): Alight-colored, wax-f I obtained by pressing paraffin distillate. 

Paraffin (wax): The wax removed from paraffin distillates by chilling and pressing. When separating from solutions, it is a 

colorless, more or less translucent, crystalline mass, without odor and taste, slightlygreasyto touch, and consisting of a 

mixture of solid hydrocarbons in which the paraffin series predominates. 

Paraffinic hydrocarbons: Straight-chain hydrocarbon compounds with the general formula CnH2n+2. 

Parent: Afirm that directly or indirectly controls another entity. 

Parent company: An affiliated com pany that exercises ultimate control over a business entity, either directly or indirectly, 

through one or more intermediaries. 

Partial requirements consumer: Awholesale consumer with generating resources insufficient to carryall its load and 

whose energy seller is a long-term firm power source supplemental to the consumer's own generation or energy received 

from others. The terms and conditions of sale are similar to those for a full requirements consumer. 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

Particulate: Asmall, discrete mass of solid or liquid matter that remains individually dispersed in gas or liquid emissions. 

Particulates take the form of aerosol, dust, fume, mist, smoke, or spray. Each of these forms has different properties. 

Passenger-miles traveled: The total distance traveled byall passengers. It is calculated as the product of the occupancy 

rate in vehicles and the vehicle miles traveled. 

Passive solar heating: A solar heating system that uses no external mechanical power, such as pumps or blowers, to 

move the collected solar heat. 

Payables to municipality: The amounts payable by the utility department to the municipality or its other departments that 

are subject to current settlement. 

Payment method for utilities: The method by which fuel suppliers or utility companies are paid for all electricity, natural 

gas, fuel oil, kerosene, or liquefied petroleum gas used bya household. Households that paythe utility company directly are 

classified as "all paid by household." Households that pay directly for at least one but not all of their fuels used and that has 

at least one fuel charge included in the rent were classified as "some paid, some included in rent." Households for which 

all fuels used are included in rent were classified as "all included in rent." If the household did not fall into one of these 

categories, it was classified as "other." Examples of households falling into the "other" category are (1)households for 

which fuel bills were paid bya social service agency or a relative, and (2) households that paid for some of their fuels used 

but paid for other fuels through another arrangement. 

PBR: Performance-Based Rates 

PBR: pebble-bed reactor 

PCB: PolyChlorinated Biphenyl 

Peak day withdrawal: The maximum daily withdrawal rate (Mcf/d) experienced during the reporting period. 

Peak demand: The maximum load during a specified period of time. 

Peak kilowatt: One thousand peak watts. 

Peak load: The maximum load during a specified period of time. 

Peak load month: The month of greatest plant electrical generation during the winter heating season (Oct-Mar) and 

summer cooling season (Apr-Sept), respectively. 

Peak load plant: A plant usually housing old, low-efficiency steam units, gas turbines, diesels, or pumped-storage 

hydroelectric equipment normally used during the peak-load periods. 

Peak megawatt: One million peak watts. 

Peak watt: A manufacturer's unit indicating the amount of power a photovoltaic cell or module will produce at standard test 

conditions (normally 1,000 watts per square meter and 25 degrees Celsius). 

Peaking capacity: Capacity of generating equipment normally reserved for operation during the hours of highest daily, 

weekly I loads. Some generating equipment may be operated at certain times as peaking capacity and at other 

times to serve loads on an around-the-clock basis. 

Peat: Peat consists of partiallydecom posed plant debris. It is considered an early stage in the development of coal. Peat is 

distinguished from lignite bythe presence of free cellulose and a high moisture content (exceeding 70 percent). The heat 

content of air-dried peat (about 50 percent moisture) is about 9 million Btu per ton. Most U.S. peat is used as a soil 

conditioner. The first U.S. electric power plant fueled by peat began operation in Maine in 1990. 

Pentanes plus: A mixture of hydrocarbons, mostly pentanes and heavier, extracted from natural gas. Includes isopentane, 

natural gasoline, and plant condensate. 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

Percent difference: The relative change in a quantity over a specified time period. It is calculated as follows the current 

value has the previous value subtracted from it; this new number is divided by the absolute value of the previous value; then 

this new number is multiplied by 100. 

Percent utilization: The ratio of total production to productive capacity, times 100. 

Perfluorocarbons(PFCs): A group of man-made chemicals composed of one or two carbon atoms and four to sixfluorine 

atoms, containing no chlorine. PFCs have no commercial uses and are emitted as a byproduct of aluminum smelting and 

semiconductor manufacturing. PFCs have very high 100-year Global Warming Potentials and are very long-lived in the 

atmosphere. 

Perfluoromethane: Acom pound (CF4) emitted as a byproduct of aluminum smelting. 

Permanently discharged fuel: Spent nuclear fuel for which there are no plans for reinsertion in the reactor core. 

Permeability: The ease with which fluid flows through a porous medium. 

Persian Gulf: The countries that surround the Persian Gulf are: Bahrain, Iran, Iraq, Kuwait, Qatar, Saudi Arabia, and the 

United Arab Emirates. See http://www.eia.doe.gov/emeu/cabs/pgulf.htmI for more information. 

Person: An individual, a corporation, a partnership, an association, a joint-stock company, a business trust, or an 

unincorporated organization. 

Person-y le year, or fraction thereof, worked by an employee, including contracted man power. Expressed as a 

quotient (to two decimal places) of the time units worked during a year (hours, weeks, or months) divided by the like total 

time units in a year. For example: 80 hours worked is 0.04 (rounded) of a person-year; 8 weeks worked is 0.15 (rounded) of 

a person-year; 12 months worked is 1 person-year. Contracted manpower includes survey crews, drilling crews, 

consultants, and other persons who worked under contract to support a firm's ongoing operations. 

Personal computer: A m icrocom puter for producing written, programmed, or coded material; playing games; or doing 

calculations. Laptop and notebook computers are excluded for the purposes of EIA surveys. 

Petrochemical f I feedstocks derived from petroleum principally for the manufacture of chemicals, 

synthetic rubber, and a variety of plastics. 

Petrochemicals: Organic and in organic compounds and mixtures that include but are not limited to organic chemicals, 

cyclic intermediates, plastics and resins, synthetic fibers, elastomers, organic dyes, organic pigments, detergents, surface 

active agents, carbon black, and ammonia. 

Petroleum: A broadly defined class of liquid hydrocarbon mixtures. Included are crude oil, lease condensate, unfinished 

oils, refined products obtained from the processing of crude oil, and natural gas plant liquids. Note: Volumes of finished 

petroleum products include non hydrocarbon compounds, such as additives and detergents, after they have been blended 

into the products. 

Petroleum Administration for Defense District (PADD): A geographic aggregation of the 50 States and the District of 

Columbia into five Districts, with PADD 1 further split into three subdistricts. The PADDs include the States listed below: 

• PADD 1 (East Coast): 

o PADD 1A (New England): Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. 

o PADD 1B (Central Atlantic): Delaware, District of Columbia, Maryland, New Jersey, New York, and 

Pennsylvania. 

o PADD 1C (Lower Atlantic): Florida, Georgia, North Carolina, South Carolina, Virginia, and West Virginia. 

• PADD 2 (Midwest): Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, North 

Dakota, Ohio, Oklahoma, South Dakota, Tennessee, and Wisconsin. 

• PADD 3 (Gulf Coast): Alabama, Arkansas, Louisiana, Mississippi, New Mexico, and Texas. 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

• PADD 4 (Rocky Mountain): Colorado, Idaho, Montana, Utah, and Wyoming. 

• PADD 5 (West Coast): Alaska, Arizona, California, Hawaii, Nevada, Oregon, and Washington. 

Map of the PADD districts 

Petroleum coke: See Coke (petroleum). 

Petroleum coke, catalyst: The carbonaceous residue that is deposited on and deactivates the catalyst used in many 

catalytic operations (e.g., catalytic cracking). Carbon is deposited on the catalyst, thus deactivating the catalyst. The catalyst 

is reactivated by burning off the carbon, which is used as a fuel in the refining process. That carbon or coke is not 

recoverable in a concentrated form. 

Petroleum coke, marketable: Those grades of coke produced in delayed or fluid cokers that maybe recovered as relatively 

pure carbon. Marketable petroleum coke maybe sold as is or further purified by calcining. 

Petroleum consumption: See Products supplied 

Petroleum imports: Imports of petroleum into the 50 states and the District of Columbia from foreign countries and from 

Puerto Rico, the Virgin Islands, and other U.S. territories and possessions. Included are imports for the Strategic Petroleum 

Reserve and withdrawals from bonded warehouses for onshore consumption, offshore bunker use, and military use. 

Excluded are receipts of foreign petroleum into bonded warehouses and into U.S. territories and U.S. Foreign Trade Zones. 

Petroleum jelly: Asemi-solid oily product produced from de-waxing lubricating oil basestocks. 

Petroleum products: Petroleum products are obtained from the processing of crude oil (including lease condensate), 

natural gas, and other hydrocarbon compounds. Petroleum products include unfinished oils, liquefied petroleum gases, 

pentanes plus, aviation gasoline, motor gasoline, naphtha-t I, kerosene-type jet fuel, kerosene, distillate fuel oil, 

residual fuel oil, petrochemical feedstocks, special naphthas, lubricants, waxes, petroleum coke, asphalt, road oil, still gas, 

and miscellaneous products. 

Petroleum refinery: An installation that manufactures finished petroleum products from crude oil, unfinished oils, natural 

gas liquids, other hydrocarbons, and alcohol. 

Petroleum stocks, primary: For individual products, quantities that are held at refineries, in pipelines and at bulk terminals 

that have a capacity of 50,000 barrels or more, or that are in transit thereto. Stocks held byproduct retailers and resellers, as 

well as tertiarystocks held at the point of consumption, are excluded. Stocks of individual products held at gas processing 

plants are excluded from individual product estimates but are included in other oils estimates and total. 

PFCs: See Perfluorocarbons 

PGA: Purchased Gas Adjustment 

pH: A m easure of acidity or alkalinity. A pH of 7 represents neutrality. Acid substances have lower pH. Basic substances 

have higher pH. 

Photosynthesis: The manufacture by plants of carbohydrates and oxygen from carbon diwdde and water in the presence of 

chlorophyll, with sunlight as the energy source. Carbon is sequestered and oxygen and water vapor are released in the 

process. 

Photovoltaic and solar thermal energy (as usedat electric utilities): Energy radiated by the sun as electromagnetic waves 

(electromagnetic radiation) that is converted at electric utilities into electricity by means of solar (photovoltaic) cells or 

concentrating (focusing) collectors. 

Photovoltaic cell (PVC): An electronic device consisting of layers of semiconductor materials fabricated to form a junction 

(adjacent layers of materials with different electronic characteristics) and electrical contacts and being capable of converting 

incident light directly into electricity (direct current). 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

Photovoltaic cell net shipments: Represents the difference between photovoltaic cell shipments and photovoltaic cell 

purchases. 

Photovoltaic module: An integrated assembly of interconnected photovoltaic cells designed to deliver a selected level of 

working voltage and current at its output terminals, packaged for protection against environmental degradation, and suited 

for incorporation in photovoltaic power systems. 

Pig iron: Crude, high-carbon iron produced by reduction of iron ore in a blast furnace. 

Pipeline (natural gas): A continuous pipe conduit, complete with such equipment as valves, compressor stations, 

communications systems, and meters for transporting natural and/or supplemental gas from one point to another, usually 

from a point in or beyond the producing field or processing plant to another pipeline or to points of utilization. Also refers to a 

corn pany operating such facilities. 

Pipeline (petroleum): Crude oil and product pipelines used to transport crude oil and petroleum products, respectively 

(including interstate, intrastate, and intracom pany pipelines), within the 50 states and the District of Columbia. 

Pipeline freight: Refers to freight carried through pipelines, including natural gas, crude oil, and petroleum products 

(excluding water). Energy is consumed byvarious electrical components of the pipeline, including, valves, other, 

appurtenances attaches to the pipe, compressor units, metering stations, regulator stations, delivery stations, holders and 

fabricated assemblies. 

Pipeline fuel: Gas consumed in the operation of pipelines, primarily in compressors. 

Pipeline purchases: Gas supply contracted from and volumes purchased from other natural gas companies as defined by 

the Natural Gas Act, as amended (52 Stat. 821), excluding independent producers, as defined in Paragraph 154.91(a), 

Chapter I, Title 18 of the Code of Federal Regulations. 

Pipeline quality natural gas: A mixture of hydrocarbon compounds existing in the gaseous phase with sufficient energy 

content, generally above 900 British thermal units, and a small enough share of impurities for transport through commercial 

gas pipelines and sale to end-users. 

Pipeline, distribution: A pipeline that conveys gas from a transmission pipeline to its ultimate consumer. 

Pipeline, gathering: A pipeline that conveys gas from a production well/field to a gas processing plant or transmission 

pipeline for eventual deliveryto end-use consumers. 

Pipeline, transmission: A pipeline that conveys gas from a region where it is produced to a region where it is to be 

distributed. 

Pipelines, rate regulated: FRS (Financial Reporting System Survey) establishes three pipeline segments: crude/liquid 

(raw materials); natural gas; and refined products. The pipelines included in these segments are all federally or State rateregulated pipeline operations, which are included in the reporting company's consolidated financial statements. However, 

at the reporting companys option, intrastate pipeline operations may be included in the U.S. Refining/Marketing Segment if 

theywould comprise less than 5 percent of U.S. Refining/Marketing Segment net PPE, revenues, and earnings in the 

aggregate; and if the inclusion of such pipelines in the consolidated financial statements adds less than $100 million to the 

net PPE reported for the U.S. Refining/Marketing Segment. 

Pitcheblende: Uranium oxide (U308). It is the main component of high-grade African or domestic uranium ore and also 

contains other oxides and sulf luding radium, thorium, and lead components. 

Place in service: A vehicle is placed in service if that vehicle is new to the fleet and has not previously been in service for 

the fleet. These vehicles can be acquired as additional vehicles (increases the size of the company fleet), or as 

replacement vehicles to replace vehicles that are being retired from service (does not increase the size of the company 

fleet). 

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Planetary albedo: The fraction of incident solar radiation that is reflected by the Earth-atmosphere system and returned to 

space, mostly by back scatter from clouds in the atmosphere. 

Planned generator: A proposal by a com pany to install electric generating equipment at an existing or planned facility or 

site. The proposal is based on the owner having obtained either (1) all environmental and regulatory approvals, (2) a signed 

contract for the electric energy, or (3) f I closure for the facility. 

Planning authority (electric): The responsible entity that coordinates and integrates transmission facility and service 

plans, resource plans, and protection systems. NERC definition 

Plant: Aterm commonly used either as a synonym for an industrial establishment or a generating facility or to refer to a 

particular process within an establishment. 

Plant condensate: One of the natural gas liquids, mostly pentanes and heavier hydrocarbons, recovered and separated as 

liquids at gas inlet separators or scrubbers in processing plants. 

Plant hours connected to load: The number of hours the plant is synchronized to load over a time interval usuallyof 1 year. 

Plant liquids: Those volumes of natural gas liquids recovered in natural gas processing plants. 

Plant or gas processing plant: Afacility designated to achieve the recovery of natural gas liquids from the stream of natural 

gas, which mayor may not have been processed through lease separators and field facilities, and to control the quality of 

the natural gas to be marketed. 

Plant products: Natural gas liquids recovered from natural gas processing plants (and in some cases from field facilities), 

including ethane, propane, butane, butane-propane mixtures, natural gasoline, plant condensate, and lease condensate. 

Plant use: The electric energy used in the operation of a plant. Included is the energy required for pumping at pumpstorage plants. 

Plant-use electricity: The electric energy used in the operation of a plant This energytotal is subtracted from the gross 

energy production of the plant. 

Play : A set of known or postulated oil and gas accumulations sharing similar geologic, geographic, and temporal 

properties, such as source rock, migration pathway, timing, trapping mechanism, and hydrocarbon type. A play differs from 

an assessment unit; an assessment unit can include one or more plays. A play is often used to refer to a natural gas 

accumulation, i.e., a natural gas shale play. http://energy.crusgs.gov/VVEcont/chaps/GL.pdf 

Plugged-back footage: Under certain conditions, drilling operations maybe continued to a greater depth than that at which 

a potentially productive formation is found. If production is not established at the greater depth, the well maybe completed 

in the shallower formation. Except in special situations, the length of the well bore from the deepest depth at which the well 

is completed to the maximum depth drilled is defined as "plugged-back footage." Plugged-back footage is included in total 

footage drilled but is not reported separately. 

Plutonium (Pu): A heavy, fissionable, radioactive, metallic element (atomic number 94) that occurs naturally in trace 

amounts. It can also result as a byproduct of the fission reaction in a uranium-f I nuclear reactor and can be recovered for 

future use. 

Pneumatic device: Adevice moved or worked by air pressure. 

Pole-mile: A unit of measuring the simple length of an electric transmission/distribution line/feeder carrying electric 

conductors, without regard to the number of conductors carried. 

Pole/Tower type: The type of transmission line supporting structure. 

Polystyrene: A polyrner of styrene that is a rigid, transparent thermoplastic with good physical and electrical insulating 

properties, used in molded products, foams, and sheet materials. 

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Polyvinyl chloride (PVC): A poly !chloride. Tasteless, odorless, insoluble in most organic solvents. Amember of 

the familyvinyl resin, used in soft fle>dble films for food packaging and in molded rigid products, such as pipes, fibers, 

upholstery, and bristles. 

Pondage: The amount of water stored behind a hydroelectric dam of relatively small storage capacity; the dam is usually 

used for daily or weekly control of the flow of the river. 

Pool: In general, a reservoir. In certain situations, a pool may consist of more than one reservoir. 

Pool site: One or more spent f I storage pools that has a single cask loading area. Each dry cask storage area is 

considered a separate site. 

Population-weighted degree-days: Heating or cooling degree-days weighted by the population of the area in which the 

degree-days are recorded. To compute national population-weighted degree-days, the Nation is divided into nine Census 

regions comprised of from three to eight states that are assigned weights based on the ratio of the population of the region 

to the total population of the Nation. Degree-day readings for each region are multiplied bythe corresponding population 

weight for each region, and these products are then summed to arrive at the national population weighted degree-day 

figure. 

Pore space: The open spaces or voids of a rock taken collectively. It is a measure of the amount of liquid or gas that may 

be absorbed or yielded by a particular formation. 

Portable electric heater: A heater that uses electricity and that can be picked up and moved. 

Portable fan: Box fans, oscillating fans, table or floor fans, or other fans that can be moved. 

Portable kerosene heater: A heater that uses kerosene and that can be picked up and moved. 

Post-mining emissions: Emissions of methane from coal occurring after the coal has been mined, during transport or 

pulverization. 

Potential consumption: The total amount of consumption that would have occurred had the intensity of consumption 

remained the same over a period of time. 

Potential peak reduction: The potential annual peak load reduction (measured in kilowatts) that can be deployed from 

Direct Load Control, Interruptible Load, Other Load Management, and Other DSM Program activities. (Please note that 

Energy Efficiency and Load Building are not included in Potential Peak Reduction.) It represents the load that can be 

reduced either by the direct control of the utility system operator or by the consumer in response to a utility request to curtail 

load. It reflects the installed load reduction capability, as opposed to the Actual Peak Reduction achieved by participants, 

during the time of annual system peak load. 

Pounds (district heat): Aweight quantity of steam, also used to denote a quantity of energy in the form of steam. The 

amount of usable energy obtained from a pound of steam depends on its temperature and pressure at the point of 

consumption and on the drop in pressure after consumption. 

Power: The rate of producing, transferring, or using energy, most commonly associated with electricity. Power is measured 

in watts and often expressed in kilowatts (kW) or megawatts (mW). Also known as "real" or "active" power. SeeActive 

Power, Apparent Power, Reactive Power, Real Power 

Power (electrical): An electric measurement unit of power called a voltampere is equal to the product of 1 volt and 1 

ampere. This is equivalent to 1 watt for a direct current system, and a unit of apparent power is separated into real and 

reactive power. Real power is the work-producing part of apparent power that measures the rate of supply of energy and is 

denoted as kilowatts (kW). Reactive power is the portion of apparent power that does no work and is referred to as kilovars; 

this type of power must be supplied to most types of magnetic equipment, such as motors, and is supplied bygenerator or 

by electrostatic equipment. Voltam peres are usually divided by 1,000 and called kilovoltamperes (kVA). Energy is denoted 

bythe product of real power and the length of time utilized; this product is expressed as kilowatthours. 

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Power ascension: The period of time between a plants initial fuel loading date and its date of first commercial operation 

(including the low-power testing period). Plants in the first operating cycle (the time from initial fuel loading to the first 

refueling), which lasts approximately 2 years, operate at an average capacity factor of about 40 percent. 

Power exchange: An entity providing a competitive spot market for electric power through day- and/or hour-ahead auction 

of generation and demand bids. 

Power exchange generation: Generation scheduled by the power exchange. See definition for power exchange. 

Power exchange load: Load that has been scheduled by the power exchange and is received through the use of 

transmission or distribution facilities owned by participating transmission owners. 

Power factor: The ratio of real power (kilowatt) to apparent power kilovolt-ampere for any given load and time. 

Power loss: The difference between electricity input and output as a result of an energy transfer between two points. 

Power marketers: Business entities engaged in buying and selling electricity. Power marketers do not usually own 

generating or transmission facilities. Power marketers, as opposed to brokers, take ownership of the electricity and are 

involved in interstate trade. These entities file with the Federal Energy Regulatory Commission (FERC) for status as a 

power marketer. 

Power pool: An association of two or more interconnected electric systems having an agreement to coordinate operations 

and planning for improved reliabilityand efficiencies. 

Power production plant: All the land and land rights, structures and improvements, boiler or reactor vessel equipment, 

engines and engine-driven generator, turbo generator units, accessory electric equipment, and miscellaneous power plant 

equipment are grouped together for each individual facility. 

Power transfer limit: The maximum power that can be transferred from one electric utilitysystem to another without 

overloading anyfacility in either system. 

Powerhouse: A structure at a hydroelectric plant site that contains the turbine and generator. 

PPE, additions to: The current year's expenditures on property, plant, and equipment (PPE). The amount is predicated upon 

each reporting corn panYs accounting practice. That is, accounting practices with regard to capitalization of certain items 

may differ across companies, and therefore this figure in FRS (Financial Reporting System) will be a function of each 

reporting companys policy. 

PPI: Producer Price Index 

Prediscovery costs: All costs incurred in an extractive industry operation prior to the actual discovery of minerals in 

corn mercially recoverable quantities; normally includes prospecting, acquisition, and exploration costs and may include 

some development costs. 

Pregnant solution: Asolution containing dissolved extractable mineral that was leached from the ore; uranium leach 

solution pumped up from the underground ore zone though a production hole. 

Preliminary permit (hydroelectric power): Asingle site permit granted by the FERC (Federal Energy Regulatory 

Commission), which gives the recipient priority over anyone else to apply for a hydroelectric license. The preliminary permit 

enables the recipient to prepare a license application and conduct various studies for economic feasibility and 

environmental impacts. The period for a preliminary permit mayextend to 3 years. 

Premium gasoline: Gasoline having an antiknock index (R+M/2) greater than 90. Includes both leaded premium gasoline 

as well as unleaded premium gasoline. 

Preparation plant: A mining facility at which coal is crushed, screened, and mechanically cleaned. 

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Preproduction costs: Costs of prospecting for, acquiring, exploring, and developing mineral reserves incurred prior to the 

point when production of commercially recoverable quantities of minerals commences. 

Pressurized-water reactor (PWR): A nuclear reactor in which heat is transferred from the core to a heat exchanger via 

water kept under high pressure, so that high temperatures can be maintained in the primary system without boiling the 

water. Steam is generated in a secondary circuit. 

Preventive maintenance program for heating and/or cooling equipment: A HVAC conservation feature consisting of a 

program of routine inspection and service for the heating and/or cooling equipment. The inspection is performed on a 

regular basis, even if there are no apparent problems. 

Price: The amount of money or consideration-in-kind for which a service is bought, sold, or offered for sale. 

Primary coal: All coal milled and, when necessary, washed and sorted. 

Primary energy: Energy in the form that it is first accounted for in a statistical energy balance, before any transformation to 

secondary or tertiary forms of energy. For example, coal can be converted to synthetic gas, which can be converted to 

electricity, in this example, coal is primary energy, synthetic gas is secondary energy, and electricity is tertiary energy. See 

Primary energy production and Primary energy consumption. 

Primary energy consumption: Consumption of primary energy. (Energy sources that are produced from other energy 

sources, e.g., coal coke from coal, are included in primary energy consumption only if their energy content has not already 

been included as part of the original energy source. Thus, U.S. primary energy consumption does include net imports of 

coal coke, but not the coal coke produced from domestic coal.) The U.S. Energy Information Administration includes the 

following in U.S. primary energy consumption: coal consumption; coal coke net imports; petroleum consumption 

(petroleum products supplied, including natural gas plant liquids and crude oil burned as fuel); dry natural gas excluding 

supplemental gaseous fuels consumption; nuclear electricity net generation (converted to Btu using the nuclear plants heat 

rates); conventional hydroelectricity net generation (converted to Btu using the fossil-f Is plant heat rates); geothermal 

electricity net generation (converted to Btu using the fossil-fuels plant heat rates), and geothermal heat pump energy and 

geothermal direct use energy, solar thermal and photovoltaic electricity net generation (converted to Btu using the fossilfuels plant heat rates), and solar thermal direct use energy, wind electricity net generation (converted to Btu using the fossilfuels plant heat rates); wood and wood-derived fuels consumption; biomass waste consumption; fuel ethanol and 

biodiesel consumption; losses and co-products from the production of fuel ethanol and biodiesel; and electricity net 

imports (converted to Btu using the electricity heat content of 3,412 Btu per kilowatthour). 

Primary energy consumption expenditures: Expenditures for energy consumed in each of the four major end-use sectors, 

excluding energy in the form of electricity, plus expenditures bythe electric utilities sector for energy used to generate 

electricity. There are no fuel-associated expenditures for associated expenditures for hydroelectric power, geothermal 

energy, photovoltaic and solar energy, or wind energy. Also excluded are the quantifiable consumption expenditures that are 

an integral part of process fuel consumption. 

Primary energy production: Production of primary energy. The U.S. Energy Information Administration includes the 

following in U.S. primary energy production: coal production, waste coal supplied, and coal refuse recovery, crude oil and 

lease condensate production; natural gas plant liquids production; dry natural gas excluding supplemental gaseous fuels 

production; nuclear electricity net generation (converted to Btu using the nuclear plant heat rates); conventional 

hydroelectricity net generation (converted to Btu using the fossil-f Is plant heat rates); geothermal electricity net generation 

(converted to Btu using the fossil-f Is plant heat rates), and geothermal heat pump energy and geothermal direct use 

energy, solar thermal and photovoltaic electricity net generation (converted to Btu using the fossil-f Is plant heat rates), 

and solar thermal direct use energy, wind electricity net generation (converted to Btu using the fossil-f Is plant heat rates); 

wood and wood-derived fuels consumption; biomass waste consumption; and biofuels feedstock. 

Primary fuels: Fuels that can be used continuously. They can sustain the boiler sufficiently for the production of electricity. 

Primary metropolitan statistical area (PMSA): A component area of a Consolidated metropolitan statistical area 

consisting of a large urbanized county or cluster of counties (cities and towns in New England) that demonstrate strong 

internal economic and social links in addition to close ties with the central core of the larger area. To qualify 

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meet specified statistical criteria that demonstrate these links and have the support of local opinion. 

Primary recovery: The crude oil or natural gas recovered by any method that maybe employed to produce them where the 

fluid enters the well bore by the action of natural reservoir pressure(energy or gravity). 

Primary transportation: Conveyance of large shipments of petroleum raw materials and refined products usually by 

pipeline, barge, or ocean-going vessel. All crude oil transportation is primary, including the small amounts moved by truck. 

All refined product transportation by pipeline, barge, or ocean-going vessel is primarytransportation. 

Prime mover: The engine, turbine, water wheel, or similar machine that drives an electric generator; or, for reporting 

purposes, a device that converts energy to electricity directly (e.g., photovoltaic solar and fuel cells). 

Prime supplier: Afirm that produces, imports, or transports selected petroleum products across State boundaries and 

local marketing areas, and sells the product to local distributors, local retailers, or end users. 

Private fueling facility: Afueling facilitywhich normallyservices onlyfleets and is not open to the general public. 

Privately owned electric utility: A class of ownership found in the electric power industry where the utility is regulated and 

authorized to achieve an allowed rate of return. 

Probable (indicated) reserves, coal: Reserves or resources for which tonnage and grade are computed partlyfrom 

specific measurements, samples, or production data and partly from projection for a reasonable distance on the basis of 

geological evidence. The sites available are too widely or otherwise in appropriately spaced to permit the mineral bodies to 

be outlined corn pletely or the grade established throughout. 

Probable energy reserves: Estimated quantities of energy sources that, on the basis of geologic evidence that supports 

projections from proved reserves, can reasonably be expected to exist and be recoverable under existing economic and 

operating conditions. Site information is insufficient to establish with confidence the location, quality the 

energy source. Note: This term is equivalent to "Indicated Reserves" as defined in the resource/reserve classification 

contained in the U.S. Geological Survey Circular 831, 1980. Measured and indicated reserves, when combined, constitute 

demonstrated reserves. 

Process cooling and refrigeration: The direct process end use in which energy is used to lower the tern perature of 

substances involved in the manufacturing process. Examples include freezing processed meats for later sale in the food 

industry and lowering the temperature of chemical feedstocks below ambient temperature for use in reactions in the 

chemical industries. Not included are uses such as air-conditioning for personal comfort and cafeteria refrigeration. 

Process fuel: All energy consumed in the acquisition, processing, and transportation of energy. Quantifiable process fuel 

includes three categories natural gas lease and plant operations, natural gas pipeline operations, and oil refinery 

operations. 

Process heating or cooling demand-side management (DSM) program: A DSM program designed to promote increased 

electric energy efficiency applications in industrial process heating or cooling. 

Process heating or cooling waste heatrecovery: An energy conservation system whereby some space heating or water 

heating is done by actively capturing byproduct heat that would otherwise be ejected into the environment. In nonresidential 

buildings, sources of waste heat include refrigeration/air-conditioner compressors, manufacturing or other processes, data 

processing centers, lighting fixtures, ventilation exhaust air, and the occupants themselves. Not to be considered is the 

passive use of radiant heat from lighting, workers, motors, ovens, etc., when there are no special systems for collecting and 

redistributing heat. 

Processed gas: Natural gas that has gone through a processing plant. 

Processing: Uranium-recovery operations whether at a mill, an in situ leach, byproduct plant, or other type of recovery 

operation. 

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Processing gain: The volumetric amount bywhich total output is greater than input for a given period of time. This 

difference is due to the processing of crude oil into products which, in total, have a lower specific gravity than the crude oil 

processed. 

Processing loss: The volumetric amount bywhich total refinery output is less than input for a given period of time. This 

difference is due to the processing of crude oil into products which, in total, have a higher specific gravity than the crude oil 

processed. 

Processing of uranium: The recovery of uranium produced by nonconventional mining methods, i.e., in situ leach mining, 

as a byproduct of copper or phosphate mining, or heap leaching. 

Processing plant: A surface installation designed to separate and recover natural gas liquids from a stream of produced 

natural gas through the processes of condensation, absorption, adsorption, refrigeration, or other methods and to control 

the quality of natural gas marketed and/or returned to oil or gas reservoirs for pressure maintenance, repressuring, or 

cycling. 

Producer: A com pany engaged in the production and sale of natural gas from gas or oil wells with delivery generallyat a 

point at or near the wellhead, the field, or the tailgate of a gas processing plant. For the purpose of company classification, a 

company primarily engaged in the exploration for, development of, and/or production of oil and/or natural gas. 

Producer and distributor coal stocks: Producer and distributor coal stocks consist of coal held in stock by 

producers/distributors at the end of a reporting period. 

Producer contracted reserves: The volume of recoverable salable gas reserves committed to or controlled by the 

reporting pipeline company as the buyer in gas purchase contracts with the independent producer as seller, including 

warranty contracts, and which are used for acts and services for which the company has received certificate authorization 

from the Federal Energy Regulatory Commission. 

Producing property: Aterm often used in reference to a property, well, or mine that produces wasting natural resources. 

The term means a propertythat produces in paying quantities (that is, one for which proceeds from production exceed 

operating expenses). 

Product supplied: Approximately represents consumption of petroleum products because it measures the disappearance 

of these products from primarysources, i.e., refineries, natural gas-processing plants, blending plants, pipelines, and bulk 

terminals. In general, product supplied of each product in any given period is computed as follows field production, plus 

refinery production, plus imports, plus unaccounted-for crude oil (plus net receipts when calculated on a PAD District basis) 

minus stock change, minus crude oil losses, minus refinery inputs, and minus exports. 

Production: See production terms associated with specific energy types. 

Production capacity: The amount of product that can be produced from processing facilities. 

Production costs: Costs incurred to operate and maintain wells and related equipment and facilities, including 

depreciation and applicable operating costs of support equipment and facilities and other costs of operating and 

maintaining those wells and related equipment and facilities. They become part of the cost of oil and gas produced. The 

following are examples of production costs (sometimes called lifting costs): costs of labor to operate the wells and related 

equipment and facilities; repair and maintenance costs; the costs of materials, supplies, and fuels consumed and services 

utilized in operating the wells and related equipment and facilities; the costs of propertytaxes and insurance applicable to 

proved properties and wells and related equipment and facilities; the costs of severance taxes. Depreciation, depletion, and 

amortization (DDA) of capitalized acquisition, exploration, and development costs are not production costs, but also become 

part of the cost of oil and gas produced along with production (lifting) costs identified above. Production costs include the 

following subcategories of costs: well workers and maintenance; operating fluid injections and improved recovery 

programs; operating gas processing plants; ad valorem taxes; production or severance taxes; other, including overhead. 

Production expenses: Costs incurred in the production of electric power that conform to the accounting requirements of 

the Operation and Maintenance Expense Accounts of the FERC Uniform System of Accounts. 

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Production payments: Acontractual arrangement providing a mineral interest that gives the owner a right to receive a 

fraction of production, or of proceeds from the sale of production, until a specified quantity of minerals (or a definite sum of 

money, including interest) has been received. 

Production plant liquids: The volume of liquids removed from natural gas in natural gas processing plants or cycling 

plants during the year. 

Production, crude oil: The volumes of crude oil that are extracted from oil reservoirs. These volumes are determined 

through measurement of the volumes delivered from lease storage tanks or at the point of custody transfer, with adjustment 

for (1) net differences between opening and closing lease inventories and (2) basic sediment and water. Crude oil used on 

the lease is considered production. 

Production, lease condensate: The volume of lease condensate produced. Lease condensate volumes include only those 

volumes recovered from lease or field separation facilities. 

Production, natural gas: The volume of natural gas withdrawn from reservoirs less (1) the volume returned to such 

reservoirs in cycling, repressuring of oil reservoirs, and conservation operations; less (2) shrinkage resulting from the 

removal of lease condensate; and less (3) nonhydrocarbon gases where they occur in sufficient quantity to render the gas 

unmarketable. Volumes of gas withdrawn from gas storage reservoirs and native gas, which has been transferred to the 

storage category, are not considered production. Flared and vented gas is also considered production. (This differs from 

"Marketed Production" which excludes flared and vented gas.) 

Production, natural gas liquids: Production of natural gas liquids is classified as follows: 

• Contract Production. Natural gas liquids accruing to a company because of its ownership of liquids extraction 

facilities that it uses to extract liquids from gas belonging to others, thereby earning a portion of the resultant liquids. 

• Leasehold Production. Natural gas liquids produced, extracted, and credited to a company's interest 

• Contract Reserves. Natural gas liquid reserves corresponding to the contract production defined above. 

• Leasehold Reserves. Natural gas liquid reserves corresponding to leasehold production defined above. 

Production, natural gas, dry: The volume of natural gas withdrawn from reservoirs during the report year less: 

1. the volume returned to such reservoirs in cycling, repressuring of oil reservoirs, and conservation operations; less 

2. shrinkage resulting from the removal of lease condensate and plant liquids; and less 

3. nonhydrocarbon gases where they occur insufficient quantityto render the gas unmarketable. 

Volumes of gas withdrawn from gas storage reservoirs and native gas, which has been tr to the storage 

category, are not considered production. This is not the same as marketed production, because the latter also 

excludes vented and flared gas, but contains plant liquids. 

Production, natural gas, wet after lease separation: The volume of natural gas withdrawn from reservoirs less (1) the 

volume returned to such reservoirs in cycling, repressuring of oil reservoirs, and conservation operations; less (2) 

shrinkage resulting from the removal of lease condensate; and less (3) nonhydrocarbon gases where they occur in 

sufficient quantityto render the gas unmarketable. Note: Volumes of gas withdrawn from gas storage reservoirs and native 

gas that has been transferred to the storage category are not considered part of production. This production concept is not 

the same as marketed production, which excludes vented and flared gas. 

Production, oil and gas: The lifting of oil and gas to the surface and gathering, treating, field processing (as in the case of 

processing gas to extract liquid hydrocarbons), and field storage. The production function shall normally be regarded as 

terminating at the outlet valve on the lease or field production storage tank. If unusual physical or operational circumstances 

exist, it maybe more appropriate to regard the production function as terminating at the first point at which oil, gas, or gas 

liquids are delivered to a main pipeline, a common carrier, a refinery, or a marine terminal. 

Production, wet after lease separation: Seeproduction, natural gas, wet after lease separation. 

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Productive capacity: The maximum amount of coal that a mining operation can produce or process during a period with 

the existing mining equipment and/or preparation plant in place, assuming that the labor and materials sufficient to utilize 

the plant and equipment are available, and that the market exists for the maximum production. 

Profit: The income remaining after all business expenses are paid. 

Program cost: Utility costs that reflect the total cash expenditures for the year, reported in nominal dollars, that flowed out to 

support DSM (demand-side management) programs. They are reported in the year they are incurred, regardless of when 

the actual effects occur. 

Propane (C3118): A normally gaseous straight-chain hydrocarbon. It is a colorless paraffinic gas that boils at a temperature 

of -43.67 degrees Fahrenheit. It is extracted from natural gas or refinery gas streams. It includes all products designated in 

ASTM Specification D1835 and Gas Processors Association Specifications for commercial propane and HD-5 propane. 

Propane air: A mixture of propane and air resulting in a gaseous fuel suitable for pipeline distribution. 

Propane, consumer grade: A normally gaseous paraffinic compound (C3H8), which includes all products covered by 

Natural Gas PolicyAct Specifications for commercial and HD-5 propane and ASTM Specification D 1835. Excludes: 

feedstock propanes, which are propanes not classified as consumer grade propanes, including the propane portion of any 

natural gas liquid mixes, i.e., butane-propane mix. 

Proportional interest in investee reserves: The proportional interest at the end of the year in the reserves of investees that 

are accounted for by the equity method. 

Proposed rates: New electric rate schedule proposed by an applicant to become effective at a future date. 

Propylene (C3H6) (nonfuel use): Propylene intended for use in nonfuel applications such as petrochemical 

manufacturing. Nonfuel propylene includes chemical-grade propylene, polymer-grade propylene, and trace amounts of 

propane. Nonfuel propylene also includes the propylene component of propane/propylene mixes where the propylene will 

be separated from the mix in a propane/propylene splitting process. Nonfuel propylene excludes the propylene component 

of propane/propylene mixes where the propylene component of the mix is intended for use as fuel. 

Propylene (C3H6): An olefinic hydrocarbon recovered from refinery processes or petrochemical processes. 

Prospecting: The search for an area of probable mineralization; the search normally includes topographical, geological, 

and geophysical studies of relatively large areas undertaken in an attempt to locate specific areas warranting detailed 

exploration. Prospecting usually occurs prior to the acquisition of mineral rights. 

Prospecting costs: Direct and indirect costs incurred to identify areas of interest that maywarrant detailed exploration. 

Such costs include those incurred for topographical, geological, and geophysical studies; rights of access to properties in 

order to conduct such studies, salaries, equipment, instruments, and supplies for geologists, including geophysical crews, 

and others conducting such studies; and overhead that can be identified with those activities. 

Proved (measured) reserves, coal: Reserves or resources for which tonnage is computed from dimensions revealed in 

outcrops, trenches, workings, and drill holes and for which the grade is computed from the results of detailed sampling. 

The sites for inspection, sampling, and measurement are spaced so closely and the geologic character is so well defined 

that size, shape, and mineral content are well established. The computed tonnage and grade are judged to be accurate 

within limits that are stated, and no such limit is judged to be different from the computed tonnage or grade by more than 20 

percent. 

Proved energy reserves: Estimated quantities of energy sources that analysis of geologic and engineering data 

demonstrates with reasonable certainty are recoverable under existing economic and operating conditions. The location, 

quantity, and grade of the energy source are usually considered to be well established in such reserves. Note: This term is 

equivalent to "Measured Reserves" as defined in the resource/reserve classification contained in the U.S. Geological Survey 

Circular 831, 1980. Measured and indicated reserves, when combined, constitute demonstrated reserves. 

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Public authorities: Electricity supplied to municipalities, divisions, or agencies of state and Federal governments, usually 

under special contracts or agreements that are applicable only to public authorities. 

Public authority service to public authorities: Public authority service includes electricity supplied and services rendered 

to municipalities or divisions or agencies of State or Federal governments under special contracts, agreements, or service 

classifications applicable only to public authorities. 

Public street and highway lighting: Electricity supplied and services rendered for the purpose of lighting streets, highways, 

parks, and other public places; or for traffic or other signal system service, for municipalities or other divisions or agencies 

of State or Federal governments. 

Public utility: Enterprise providing essential public services, such as electric, gas, telephone, water, and sewer under 

legally established monopoly conditions. 

Public utility district: Municipal corporations organized to provide electric service to both incorporated cities and towns and 

unincorporated rural areas. 

Public Utility Holding Company Act of 1935 (PUHCA): This act prohibits acquisition of anywholesale or retail electric 

business through a holding company unless that business forms part of an integrated public utilitysystem when combined 

with the utility's other electric business. The legislation also restricts ownership of an electric business by non-utility 

corporations. 

Public Utility Regulatory Policies Act of 1978: The Public Utility Regulatory Policies Act of1978, passed by the U.S. 

Congress. This statute requires States to implement utility conservation programs and create special markets for cogenerators and small producers who meet certain standards, including the requirement that States set the prices and 

quantities of power the utilities must buyfrom such facilities. 

Public Utility Regulatory PoliciesAct (PURPA) of 1978: One part of the National Energy Act, PURPA contains measures 

designed to encourage the conservation of energy, more efficient use of resources, and equitable rates. Principal among 

these were suggested retail rate reforms and new incentives for production of electricity by cogenerators and users of 

renewable resources. The Commission has primary authorityfor implementing several key PURPA programs. 

Publicly owned electric utility: A class of ownership found in the electric power industry. This group includes those utilities 

operated by municipalities and State and Federal power agencies. 

PUD: See Public Utility District 

PUHCA: See Public Utility Holding Company Act of 1935 

Pulp chips: Timber or residues processed into small pieces of wood of more or less uniform dimensions with minimal 

amounts of bark. 

Pulp wood: Roundwood, whole-tree chips, or wood residues. 

Pulping liquor (black liquor): The alkaline spent liquor removed from the digesters in the process of chemically pulping 

wood. After evaporation, the liquor is burned as a fuel in a recovery furnace that permits the recovery of certain basic 

chemicals. 

Pumped-storage hydroelectric plant: A plant that usually generates electric energy during peak load periods by using 

water previously pumped into an elevated storage reservoir during off-peak periods when excess generating capacity is 

available to do so. When additional generating capacity is needed, the water can be released from the reservoir through a 

conduit to turbine generators located in a power plant at a lower level. 

Purchase-contract imports of uranium: The amount of foreign-origin uranium material that enters the United States 

during a survey year as reported on the "Uranium IndustryAnnual Survey (UIAS), Form EIA-858, as purchases of uranium 

ore, U308, natural UF6, or enriched UF6. The amount of foreign-origin uranium materials that enter the country during a 

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survey year under other types of contracts, i.e., loans and exchanges, is excluded. 

Purchased: Receipts into transportation, storage, and/or distribution facilities within a state under gas purchase contracts 

or agreements whether or not billing or payment occurred during the report year. 

Purchased power: Power purchased or available for purchase from a source outside the system. 

Purchased power adjustment: A clause in a rate schedule that provides for adjustments to the bill when energyfrom 

another electric system is acquired and its cost varies from a specified unit base amount. 

Pure pumped-storage hydroelectric plant: A plant that produces power only from water that has previously been pumped 

to an upper reservoir. 

PURPA: See Public Utility Regulatory Policies Act of 1978 

PV: Photovoltaic 

PVC: See Photovoltaic Cell; polyvinyl chloride 

PVCs that convert sunlight directly into energy: A method for producing energy by converting sunlight using photovoltaic 

cells (PVCs) that are solid-state single converter devices. Although currently not in wide usage, commercial customers have 

a growing interest in usage and, therefore, DOE has a growing interest in the impact of PVCs on energy consumption. 

Economically lectricity. 

PWR: See Pressurized-Water Reactor 

Pyrolysis: The thermal decomposition of biomass at high temperatures (greater than 400° F, or 200° C) in the absence of 

air. The end product of pyrolysis is a mixture of solids (char), liquids (oxygenated oils), and gases (methane, carbon 

monoxide, and carbondioxide) with proportions determined by operating temperature, pressure, oxygen content, and other 

conditions. 

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Glossary 

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Q 

QF: SeeQualify lity 

QUAD: Quadrillion Btu 10

15 

Btu. 

Quadrillion: The quantity 1,000,000,000,000,000(10 to the 15th power). 

Qualifying facility (QF): A cogeneration or small power production facility that meets certain ownership, operating, and 

eff lished bythe Federal Energy RegulatoryCommission (FERC) pursuant to the Public Utility 

Regulatory Policies Act (PURPA). 

Quality or grade (of coal): An informal classification of coal relating to its suitability for use for a particular purpose. Refers 

to individual measurements such as heat value, f , moisture, ash, sulf , major, minor, and trace elements, 

coking properties, petrologic properties, and particular organic constituents. The individual quality elements maybe 

aggregated in various ways to classify coal for such special purposes as metallurgical, gas, petrochemical, and blending 

usages. 

Quantity wires charge: Afee for moving electricity over the transmission and/or distribution system that is based on the 

quantity of electricity that is transmitted. 

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Glossary 

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R 

R-value: A measure of a material's resistance to heat flow in units of Fahrenheit degrees x hours x square feet per Btu. The 

higher the R-value of a material, the greater its insulating capability. The R-value of some insulating materials is 3.7 per 

inch for fiber glass and cellulose, 2.5 per inch for vermiculite, and more than 4 per inch for foam. All building materials have 

some R-value. For example, a 4-inch brick has an R-value of 0.8, and half-inch plywood has an R-value of 0.6. The table 

below converts the most common "R" values to inches. For other "R" values, divide the "R" value by 3 to get the number of 

inches. 

"R"-Value Inches 

3 1 

11 3.5 

19 6 

52 18 

RAC: Refiners' Acquisition Cost. 

Rack sales: Wholesale truckload sales or smaller of gasoline where title transfers at a terminal. 

Radiant barrier: A thin, reflective foil sheet that exhibits low radiant energy transm ission and under certain conditions can 

block radiant heat transfer; installed in attics to reduce heat flow through a roof assembly into the living space. 

Radiant ceiling panels: Ceiling panels that contain electric resistance heating elements embedded within them to provide 

radiant heat to a room. 

Radiant energy: Energythat transmits awayfrom its source in all directions. 

Radiation: The transfer of heat through matter or space by means of electromagnetic waves. 

Radiative forcing: A change in average net radiation at the top of the troposphere (known as the tropopause) because of a 

change in either incoming solar or exiting infrared radiation. A positive radiative forcing tends on average to warm the earth's 

surface; a negative radiative forcing on average tends to cool the earth's surface. Greenhouse gases, when emitted into the 

atmosphere, trap infrared energy radiated from the earth's surface and therefore tend to produce positive radiative forcing. 

Also see Greenhouse gases. 

Radiatively active gases: Gases that absorb incoming solar radiation or outgoing infrared radiation, affecting the vertical 

temperature profile of the atmosphere. Also seeRadiative forcing. 

Radiator: A heating unit usually exposed to view within the room or space to be heated; it transfers heat by radiation to 

objects within visible range and by conduction to the surrounding air, which in turn is circulated by natural convection; 

usuallyfed by steam or hot water. 

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9/19/12 Glossary - U.S. Energy Information Administration (EIA) 

Radioactive waste: Materials left over from making nuclear energy. Radioactive waste can destroy living organisms if it is 

not stored safely. 

Radioactivity: The spontaneous emission of radiation from the nucleus of an atom. Radionuclides lose particles and 

energythrough this process. 

Radioisotope: A radioactive isotope. 

Radon: A naturally occurring radioactive gas found in the United States in nearly all t I, rock, and water. It can 

migrate into most buildings. Studies have linked high concentrations of radon to lung cancer. 

Rail (method of transportation to consumers): Shipments of coal moved to consumers by rail (private or 

public/commercial). Includes coal hauled to or awayfrom a railroad siding by truck. 

Railroad and railway electric service: Electricity supplied to railroads and interurban and street railways, for general 

railroad use, including the propulsion of cars or locomotives, where such electricity is supplied under separate and distinct 

rate schedules. 

Railroad locomotive: Self-propelled vehicle that runs on rails and is used for moving railroad cars. 

Railroad use: Sales to railroads for any use, including that used for heating buildings operated by railroads. 

Range top: The range burners or stove top and the oven are considered two separate appliances. Counted also with range 

tops are stand-alone "cook tops." 

Rankine cycle: The thermodynamic cycle that is an ideal standard for comparing performance of heat-engines, steam 

power plants, steam turbines, and heat pump systems that use a condensable vapor as the working fluid. Eff 

le heat supplied. 

Rankine cycle engine: The Rankine cycle system uses a liquid that evaporates when heated and expands to produce 

work, such as turning a turbine, which when connected to a generator, produces electricity. The exhaust vapor expelled from 

the turbine condenses and the liquid is pumped back to the boiler to repeat the cycle. The working fluid most commonly 

used is water, though other liquids can also be used. Rankine cycle design is used by most commercial electric power 

plants. The traditional steam locomotive is also a common form of the Rankine cycle engine. The Rankine engine itself can 

be either a piston engine or a turbine. 

RAR: See Reasonable Assured Resources. 

Rate base: The value of property upon which a utility is permitted to earn a specified rate of return as established bya 

regulatory authority. The rate base generally represents the value of property used bythe utility in providing service and may 

be calculated by any one or a combination of the following accounting methods: fair value, prudent investment, reproduction 

cost, or original cost. Depending on which method is used, the rate base includes cash, working capital, materials and 

supplies, deductions for accumulated provisions for depreciation, contributions in aid of construction, customer advances 

for construction, accumulated deferred income taxes, and accumulated deferred investment tax credits. 

Rate base (electric): The value of property tility is permitted to earn a specified rate of return as 

established bya regulatory authority. See FERC definition. 

Rate case: A proceeding, usually before a regulatory comm ission, involv lic utility 

service. 

Rate features: Special rate schedules or tariffs offered to customers by electric and/or natural gas utilities. 

Rate of return: The ratio of net operating income earned bya utility is calculated as a percentage of its rate base. 

Rate of return on rate base: The ratio of net operating income earned bya utility, calculated as a percentageof its rate 

base. 

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Rate schedule (electric): The rates, charges, and provisions under which service is supplied to the designated class of 

customers. SeeFERC definition. 

Ratemaking authority: A utility commission's legal authorityto fix, modify, approve, or disapprove rates as determined by 

the powers given the commission by a State or Federal legislature. 

Rates: The authorized charges per unit or level of consumption for a specified time period for any of the classes of utility 

services provided to a customer. 

Rating: A manufacturer's guaranteed performance of a machine, transmission line, or other electrical apparatus, based on 

design features and test data. The rating will specify such limits as load, voltage, temperature, and frequency. The rating is 

generally printed on a nameplate attached to equipment and is commonly referred to as the nameplate rating or nameplate 

capacity. 

Ratio estimate: The ratio of two population aggregates (totals). For example, "average miles traveled per vehicle" is the 

ratio of total miles driven by all vehicles, over the total number of vehicles, within any subgroup. There are two types of ratio 

estimates those computed using aggregates for vehicles and those computed using aggregates for households. 

Ratoon crop: A crop cultivated from the shoots of a perennial plant. 

Rayleigh frequency distribution: A mathematical representation of the frequency or ratio that specific wind speeds occur 

within a specified time interval. 

RBOB: Reformulated Gasoline Blendstockfor Oxygenate Blending. 

RDF: SeeRefuse-Derived Fuel. 

REA: SeeRural Electrification Administration. 

Reactance: A phenomenon associated with AC power characterized by the existence of a time difference between voltage 

and current variations. 

Reactive power: The portion of electricity that establishes and sustains the electric and magnetic fields of alternatingcurrent equipment. Reactive power must be supplied to most types of magnetic equipment, such as motors and 

transformers. Reactive power is provided by generators, synchronous condensers, or electrostatic equipment such as 

capacitors and directly influences electric system voltage. It is a derived value equal to the vector difference between the 

apparent power and the real power. It is usually expressed as kilovolt-amperes reactive (K ) or megavolt-ampere 

reactive (M ). SeeApparent Power, Power, Real Power. 

Real dollars: These are dollars that have been adjusted for inflation. 

Real Power: The component of electric power that performs work, typically measured in kilowatts (kW) or m egawatts(MW)-- 

sometimes referred to as Active Power. The terms "real" or "active" are often used to modify the base term "power" to 

differentiate it from Reactive Power and Apparent Power. SeeApparent Power, Power, Reactive Power. 

Real price: A price that has been adjusted to remove the effect of changes in the purchasing power of the dollar. Real 

prices, which are expressed in constant dollars, usually reflect buying power relative to a base year. 

Reasonably assured resources (RAR): The uranium that occurs in known mineral deposits of such size, grade, and 

configuration that it could be recovered within the given production cost ranges, with currently proven mining and processing 

technology. Estimates of tonnage and grade are based on specific sample data and measurements of the deposits and on 

knowledge of deposit characteristics. RAR correspond to DOE's Reserves category. 

Rebate program: A utility company-sponsored conservation program whereby the utility company returns a portion of the 

purchase price cost when a more energy-efficient refrigerator, water heater, air conditioner, or other appliance is purchased. 

Reburn: An advanced co-f technique using natural gas to reduce pollution from electric power plants. 

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Receipts: 

• Deliveries of fuel to an electric plant 

• Purchases of fuel 

• All revenues received byan exporter for the reported quantity exported 

• Also see Received. 

Receivables from municipality: All charges by the utility department against the municipality or its other departments that 

are subject to current settlement. 

Received: Gas (and other fuels) physicallytransferred into the responding corn panys transportation, storage, and/or 

distribution facilities. 

Reclamation: Process of restoring surface environment to acceptable pre-existing conditions. Includes surface contouring, 

equipment removal, well plugging, revegetation, etc. 

Reclamation expenses: In the context of the coal operation statement of income, refers to all payments made by the 

corn pany attributable to reclamation, including taxes. 

Recoverability: In reference to accessible coal resources, the condition of being physically, technologically, and 

economically m fable. Recovery rates and recovery factors maybe determined or estimated for coal resources without 

certain knowledge of their economic m inability, therefore, the availability of recovery rates or factors does not predict 

recoverability. 

Recoverable coal: Coal that is, or can be, extracted from a coal bed during mining. 

Recoverable proved reserves: The proved reserves of natural gas as of December 31 of any given year are the estimated 

quantities of natural gas which geological and engineering data demonstrates with reasonable certainty to be recoverable 

in the future from known natural oil and gas reservoirs under existing economic and operating conditions. 

Recoverable reserves: The amount of coal that can be recovered (mined) f I deposits at active producing mines 

as of the end of the year. 

Recoverable reserves, estimated recoverable reserves (coal) : Reserve estimates (broad meaning) based on a 

demonstrated reserve base adjusted for assumed accessibility factors and recoveryfactors. The term is used by EIA to 

distinguish estimated recoverable reserves, which are derived without specific economic feasibility criteria byfactoring 

(downward) from a demonstrated reserve base for one or more study areas or regions, from recoverable reserves at active 

mines, which are aggregated (upward) from reserve estimates reported by currently active, economically viable mines on 

Form EIA-7A 

Recovery factor (coal): The percentage of total tons of coal estimated to be recoverable from a given area in relation to the 

total tonnage estimated to be in the demonstrated reserve base. The estimated recovery factors for the demonstrated 

reserve base generally are 50 percent for underground mining methods and 80 percent for surface mining methods. More 

precise recovery factors can be computed by determining the total coal in place and the total recoverable in any specific 

locale. 

Recovery percentage (coal): The percentage of coal that can be recovered from the coal deposits at existing mines. 

RECS: See Residential Energy Consumption Survey. 

Rectifier: Adevice for converting alternating current to direct current. 

Recycled feeds: Feeds that are continuously fed back for additional processing. 

Recycling: The process of converting materials that are no longer useful as designed or intended into a new product. 

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Redox potential: A measurement of the state of oxidation of a system. 

Redrill footage: Occasionally, a hole is lost or junked and a second hole maybe drilled from the surface in close proximity 

to the first. Footage drilled for the second hole is defined as "redrill footage." Under these circumstances, the first hole is 

reported as a dry hole (explanatory or developmental) and the total footage is reported as dry hole footage. The second hole 

is reported as an oil well, gas well, or dry hole according to the result. The redrill footage is included in the appropriate 

classification of total footage, but is not reported as a separate classification. 

Reduced use-off hours: A conservation feature consisting of manually or automatically reducing the amount of heating or 

cooling produced during the hours a building is not in full use. 

Reference month: The calendar month and year to which the reported cost, price, and volume information relates. 

Reference year: The calendar year to which the reported sales volume information relates. 

Refined coal: A coal product that is created when impurities and/or moisture are removed to improve heat content and 

reduce emissions. Includes any coal that meets the IRS definition of refined coal (Notice 2010-54 or any superseding IRS 

notices). Does not include coal processed by coal preparation plants. 

Refined petroleum products: Refined petroleum products include but are not limited to gasolines, kerosene, distillates 

(including No. 2 fuel oil), liquefied petroleum gas, asphalt, lubricating oils, diesel fuels, and residual fuels. 

Refiner: Afirm or the part of a firm that refines products or blends and substantially changes products, or refines liquid 

hydrocarbons from oil and gas field gases, or recovers liquefied petroleum gases incident to petroleum refining and sells 

those products to resellers, retailers, reseller/retailers or ultimate consumers. "Refiner" includes any owner of products that 

contracts to have those products refined and then sells the refined products to resellers, retailers, or ultimate consumers. 

Refiner acquisition cost of crude oil: The cost of crude oil, including transportation and other fees paid by the refiner. The 

composite cost is the weighted average of domestic and imported crude oil costs. Note: The refiner acquisition cost does 

not include the cost of crude oil purchased for the Strategic Petroleum Reserve (SPR). 

Refinery: An installation that manufactures finished petroleum products from crude oil, unfinished oils, natural gas liquids, 

other hydrocarbons, and oxygenates. 

Refinery and blender net inputs: Raw materials, unfinished oils, and blending components processed at refineries, or 

blended at refineries or petroleum storage terminals to produce finished petroleum products. Included are gross inputs of 

crude oil, natural gas plant liquids, other hydrocarbon raw materials, hydrogen, oxygenates (excluding fuel ethanol), and 

renewable fuels (including fuel ethanol). Also included are net inputs of unfinished oils, motor gasoline blending 

components, and aviation gasoline blending components. Netinputs are calculated as gross inputs minus gross 

production. Negative net inputs indicate gross inputs are less than gross production. Examples of negative net inputs 

include reformulated gasoline blendstock for oxygenate blending (RBOB) produced at refineries for shipment to blending 

terminals, and unfinished oils produced and added to inventory in advance of scheduled maintenance of a refinerycrude oil 

distillation unit. 

Refinery and blender net production: Liquefied refinery gases, and finished petroleum products produced at a refineryor 

petroleum storage terminal blending facility. Netproduction equals gross production minus gross inputs. Negative net 

production indicates gross production is less than gross inputs for a finished petroleum product. Examples of negative net 

production include reclassification of one finished product to another finished product, or reclassification of a finished 

product to unfinished oils or blending components. 

Refinery capacity utilization: Ratio of the total amount of crude oil, unfinished oils, and natural gas plant liquids run 

through crude oil distillation units to the operable capacity of these units. 

Refinery fuel: Crude oil and petroleum products consumed at the refineryfor all purposes. 

Refinery gas: Non condensate gas collected in petroleum refineries. 

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Refinery input, crude oil: Total crude oil (domestic plus foreign) input to crude oil distillation units and other refinery 

processing units (cokers, etc.). 

Refinery input, total: The raw materials and intermediate materials processed at refineries to produce finished petroleum 

products. They include crude oil, products of natural gas processing plants, unfinished oils, other hydrocarbons and 

oxygenates, motor gasoline and aviation gasoline blending components and finished petroleum products. 

Refinery losses and gains: Processing gain and loss that takes place during the refining process itself. Excludes losses 

that do not take place during the refining process, e.g., spills, fire losses, and contamination during blending, 

transportation, or storage. 

Refinery output: The total amount of petroleum products produced at a refinery. Includes petroleum consumed bythe 

refinery. 

Refinery production: Petroleum products produced at a refinery or blending plant. Published production of these products 

equals refinery production minus refinery input. Negative production will occur when the amount of a product produced 

during the month is less than the amount that is reprocessed (input) or reclassified to become another product during the 

same month. Refinery production of unfinished oils and motor and aviation gasoline blending components appear on a net 

basis under refinery input. 

Refinery utilization rate: Represents the use of the atmospheric crude oil distillation units. The rate is calculated by 

dividing the gross input to these units by the operable refining capacity of the units. 

Refinery yield: Refineryyield (expressed as a percentage) represents the percent of finished product produced from input 

of crude oil and net input of unfinished oils. It is calculated by dividing the sum of crude oil and net unfinished input into the 

individual net production of finished products. Before calculating the yield for finished motor gasoline, the input of natural 

gas liquids, other hydrocarbons and oxygenates, and net input of motor gasoline blending components must be subtracted 

from the net production of finished aviation gasoline. 

Refinery-grade butane: A refinery produced stream that is composed predominantlyof normal butane and/or isobutane 

and may also contain propane and/or natural gasoline. These streams may also contain significant levels of olefins and/or 

fluorides contamination. 

Reflective film: Transparent covering for glass that helps keep out heat f the sun. 

Reflectivity: The ratio of the energy carried by a wave after reflection from a surface to its energy before reflection. 

Reforestation: Replanting of forests on lands that have recently been harvested or otherwise cleared of trees. 

Reformulated blendstock for oxygenate blending (RBOB): Motor gasoline blending components intended for blending 

with oxygenates to produce finished reformulated gasoline. 

Reformulated gasoline: Finished gasoline formulated for use in motor vehicles, the composition and properties of which 

meet the requirements of the reformulated gasoline regulations promulgated bythe U.S. Environmental Protection Agency 

under Section 211(k) of the Clean Air Act. It includes gasoline produced to meet or exceed emissions performance and 

benzene content standards of federal-program reformulated gasoline even though the gasoline may not meet all of the 

composition requirements (e.g. oxygen content) of federal-program reformulated gasoline. Note: This category includes 

Oxygenated Fuels Program Reformulated Gasoline (OPRG). Reformulated gasoline excludes Reformulated Blendstock for 

Oxygenate Blending (RBOB) and Gasoline Treated as Blendstock (GTAB). 

Refrigeration unit: Lowers the temperature through a mechanical process. In a typical refrigeration unit, electricity powers a 

motor that runs a pump to compress the refrigerant to maintain proper pressure. (A"refrigerant" is a substance that 

changes between liquid and gaseous states under desirable temperature and pressure conditions.) Heat from the 

compressed liquid is removed and discharged from the unit and the refrigerant then evaporates when pressure is reduced. 

The refrigerant picks up heat as it evaporates and it returns to the compressor to repeat the cycle. Afew refrigeration units 

use gas (either natural gas or LPG) in an absorption process that does not use a corn pressor. The gas is burned to heat a 

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chemical solution in which the refrigerant has been absorbed. Heating drives off there frigerant which is later condensed. 

The condensed refrigerant evaporates by a release of pressure, and it picks up heat as it evaporates. The evaporated 

refrigerant is then absorbed back into the chemical solution, the heat is removed from the solution and discharged as 

waste heat, and the process repeats itself. By definition, refrigerators, freezers, and air-conditioning equipment all contain 

refrigeration units. 

Refunding: Retirement of one security issue with proceeds received from selling another. Refunding provides for retiring 

maturing debt by taking advantage of favorable money market conditions. 

Refuse bank: A repositoryfor waste material generated bythe coal cleaning process. 

Refuse mine: Asurface mine where coal is recovered from previously mined coal. It may also be known as a silt bank, 

culm bank, refuse bank, slurry dam, or dredge operation. 

Refuse recovery: The recapture of coal from a refuse mine or the coal recaptured by that process. The resulting product 

has been cleaned to reduce the concentration of noncombustible materials. 

Refuse-derived fuel (RDF): Afuel produced by shredding municipal solid waste (MSW). Noncombustible materials such as 

glass and metals are generally removed prior to making RDF. The residual material is sold as-is or compressed into 

pellets, bricks, or logs. RDF processing facilities are typically located near a source of MSW, while the RDF combustion 

facility can be located elsewhere. 

Regional reserves, regional reserve estimates (coal): Same as reserves; alternative wording is used by EIA to distinguish 

regional reserves, which are derived by factoring (downward) f 

t active mines, which are aggregated (upward) from reserve estimates reported by 

individual mines on Form EIA-7A. 

Regional Transmission Group: A utility industry concept that the Federal Energy Regulatory Comm iss ion (FERC) 

embraced for the certification of voluntary groups that would be responsible for transmission planning and use on a 

regional basis. 

Regular grade gasoline: Agrade of unleaded gasoline with a lower octane rating (approximately 82) than other grades. 

Octane boosters are added to gasoline to control engine pre-ignition or "knocking" by slowing combustion rates. 

Regulated entity: For the purpose of ETA's data collection efforts, entities that either provide electricity within a designated 

franchised service area and/or file forms listed in the Code of Federal Regulations, Title 18, part 141 are considered 

regulated entities. This includes investor-owned electric utilities that are subject to rate regulation, municipal utilities, 

federal and state power authorities, and rural electric cooperatives. Facilities that qualify as cogenerators or small power 

producers under the Public Utility Regulatory Power Act (PURPA) are not considered regulated entities. 

Regulated streamflow: The rate of flow past a given point during a specified period that is controlled by reservoir water 

release operation. 

Regulation: The governmental function of controlling or directing economic entities through the process of rulemaking and 

adjudication. 

Regulation, procedures, and practices: A utility corn mission carries out its regulatory functions through rulemaking and 

adjudication. Under rulemaking, the utilitycommission may propose a general rule of regulation change. Bylaw, it must 

issue a notice of the proposed rule and a request for comments is also made; the Federal Energy Regulatory Com mission 

publishes this in the Federal Register. The final decision must be published. A utilitycommission mayalso work on a caseby-case basis from submissions from regulated companies or others. Objections to a proposal may come from the 

commission or intervenors, in which case the proposal must be presented to a hearing presided over by an administrative 

law judge. The judge's decision maybe adopted, modified, or reversed bythe utilitycommissioners, in which case those 

involved can petition for a rehearing and may appeal a decision through the courts system to the U.S. Supreme Court. 

Reheating coils: Apart of some air-conditioning systems. Electric coils in air ducts used primarily to raise the temperature 

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of circulated air after it was over-cooled to remove moisture. Some buildings have reheating coils as their sole heating 

source. 

Reid Vapor Pressure (RVP): An indirect measure of the rate at which petroleum liquids evaporate. Its the absolute vapor 

pressure of a crude oil, or of single or mixed liquid petroleum products, as measured bythe Reid Method (ASTM Method D 

323). 

Reinjected: The forcing of gas under pressure into an oil reservoir in an attempt to increase recovery. 

Reinserted fuel: Irradiated fuel that is discharged in one cycle and inserted in the same reactor during a subsequent 

refueling. In a few cases, fuel discharged from one reactor has been used to fuel a different reactor. 

Reinsertion: The process of returning nuclear fuel that has been irradiated and then removed from a reactor back into a 

reactor for further irradiation. Reinserted assemblies are assemblies that have been irradiated in a cycle, were not in the 

core in the prior cycle (cycle N), and which are in the core in the current cycle (cycle N+1). 

Reliability (electric system): A measure of the ability of the system to continue operation while some lines or generators 

are out of service. Reliability deals with the performance of the system under stress. 

Reliability coordinator (electric): The entity that is the highest level of authoritywho is responsible for the reliable operation 

of the Bulk Electric System, has the Wide Area view of the Bulk Electric System, and has the operating tools, processes and 

procedures, including the authorityto prevent or mitigate emergency operating situations in both next-day analysis and realtime operations. The Reliability Coordinator has the purview that is broad enough to enable the calculation of 

Interconnection Reliability Operating Limits, which maybe based on the operating parameters of transmission systems 

beyond any Transmission Operators vision. See NERC definition. 

Relocation of tailings: Relocation of tailings is sometimes necessary if the pile poses a threat to inhabitants or the 

environment, for example, through being situated too close to populated areas, on top of aquifers or other sources of water, 

or in unstable areas such as flood plains or faults near earthquake zones. 

Remaining (resources/reserves) (coal) : The amount of coal in the ground after some mining, excluding coal in the ground 

spoiled or left in place for which later recovery is not feasible. 

Renewable diesel fuel (other): Diesel f I and diesel f I blending components produced from renewable sources that 

are coprocessed with petroleum feedstocks and meet requirements of advanced biofuels. Note: This category"other" 

pertains to the petroleum supply data system. 

Renewable energy resources: Energy resources that are naturally replenishing but flow-limited. They are virtually 

inexhaustible in duration but limited in the amount of energy that is available per unit of time. Renewable energy resources 

include biomass, hydro, geothermal, solar, wind, ocean thermal, wave action, and tidal action. 

Renewable fuels (other): Fuels and fuel blending components, except biomass-based diesel f I, renewable diesel f I, 

and fuel ethanol, produced from renewable biomass. Note: This category"other" pertains to the petroleum supply data 

system. 

Replacement energy source for primary heating: For the CBECS (an ElAconsumption survey), the heating energy source 

to which the building could switch within one week without major modifications to the main heating equipment, without 

substantially reducing the area heated, and without substantially reducing the temperature maintained in the heated area. 

Replacement vehicle: Avehicle which is acquired in order to take the place of a vehicle which is being retired from service. 

These acquisitions do not increase the size of the companyfleet. 

Report State: The State, including adjacent offshore continental shelf areas in the Federal domain, in which a company 

operated natural gas gathering, transportation, storage, and/or distribution facilities or a synthetic natural gas plant covered 

by the individual report. 

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Report week: Acalendar week beginning at 12:01a.m. on Sundayand ending at midnight on Saturday. 

Report year (calendar): The 12-month period, January 1 through December 31 

Report year (fiscal): A 12-month period for which an organization plans the use of its funds. The fiscal year is designated 

bythe calendar year in which it ends. 

Reporting: The average number of Btu per cubic foot of gas at 60 degrees Fahrenheit and 14.73 psia delivered directlyto 

consumers. Where billing is on a thermal basis, the heat content values used for billing purposes are to be used to 

determine the annual average heat content. 

Repowering: Refurbishment of a plant by replacement of the combustion technology with a new combustion technology, 

usually resulting in better performance and greater capacity. 

Repressuring: The injection of gas into oil or gas formations to effect greater ultimate recovery. 

Reprocessing: Synonymous with chemical separations. 

Requirements power: The firm service needs required by designated load plus losses from the points of supply. 

Reregulation: The design and implementation of regulatory practices to be applied to the remaining regulated entities after 

restructuring of the vertically-integrated electric utility. The remaining regulated entities would be those that continue to 

exhibit characteristics of a natural monopoly lization of more competitive 

results, and where, in light of other policy considerations, competitive results are unsatisfactory in one or more respects. 

Regulation could employthe same or different regulatory practices as those used before restructuring. 

Resale (wholesale) sales: Resale or wholesale sales are electricity sold (except under exchange agreements) to other 

electric utilities or to public authorities for resale distribution. (This includes sales to requirements and nonrequirements 

cons urn ers .) 

Research and development (RD): Basic and applied research in the sciences and engineering and the design and 

development of prototypes and processes, excluding quality control, routine product testing, market research, sales 

promotion, sales service, research in the social sciences or psychology, and other non-technological activities or technical 

services. 

Reseller: Afirm (other than a refiner) that is engaged in a trade or business that buys refined petroleum products and then 

sells them to a purchaser who is not the ultimate consumer of those refined products. 

Reserve: That portion of the demonstrated reserve base that is estimated to be recoverable at the time of determination. 

The reserve is derived by applying a recoveryfactor to that component of the identified coal resource designated as the 

demonstrated reserve base. 

Reserve additions: The estimated original, recoverable, salable, and new proved reserves credited to new fields, new 

reservoirs, new gas purchase contracts, amendments to old gas purchase contracts, or purchase of gas reserves in-place 

that occurred during the year and had not been previously reported. Reserve additions refer to domestic in-the-ground 

natural gas reserve additions and do not refer to interstate pipeline purchase agreements; contracts with foreign suppliers; 

coal gas, SNG, or LNG purchase arrangements. 

Reserve cost categories of $15, $30, $50, and$100 per pound U308: Classification of uranium reserves estimated by 

using break-even cut-off grades that are calculated based on forward-operating costs of less than $15, $30, $50, and $100 

per pound U308. 

Reserve generating capacity: Amount of generating capacity available to meet peak or abnormally high demands for 

power and to generate power during scheduled or unscheduled outages. 

Reserve margin (operating): The amount of unused available capability of an electric power system (at peak load for a 

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utility system) as a percentage of total capability. 

Reserve revisions: Changes to prior year-end proved reserves estimates, either positive or negative, resulting from new 

information other than an increase in proved acreage(extension). Revisions include increases of proved reserves 

associated with the installation of improved recovery techniques or equipment. They also include correction of prior year 

arithmetical or clerical errors and adjustments to prior year-end production volumes to the extent that these alter reserves 

estimates. 

Reserves changes: Positive and negative revisions, extensions, new reservoir discoveries in old fields, and new field 

discoveries that occurred during the report year. 

Reserves, coal: Quantities of unextracted coal that comprise the demonstrated base for future production, including both 

proved and probable reserves. Also seeProved energy reserves; Probable energy reserves; Energy reserves; Proved 

(measured) reserves, coal; and Probable(indicated) reserves, coal. 

Reserves, energy: SeeProved energy reserves. 

Reserves, net: Includes all proved reserves associated with the companys net working interests. 

Reservoir: A porous and permeable underground formation containing an individual and separate natural accumulation of 

producible hydrocarbons (crude oil and/or natural gas) which is confined by impermeable rock or water barriers and is 

characterized by a single natural pressure system. 

Reservoir capacity: The present total developed capacity (base and working) of the storage reservoir, excluding 

contemplated future development. 

Reservoir repressuring: The injection of a pressurized fluid (such as air, gas, or water) into oil and gas reservoir 

formations to effect greater ultimate recovery. 

Residential building: Astructure used primarily as a dwelling for one or more households. 

Residential consumers: Consumers using gas for heating, air conditioning, cooking, water heating, and other residential 

uses in single and multi-familydwellings and apartments and mobile homes. 

Residential energy consumption survey (RECS): A national multistage probability sam ple survey conducted bythe Energy 

End Use Division of the Energy Information Administration. The RECS provides baseline information on how households in 

the United States use energy. The Residential Transportation Energy Consumption Survey (RTECS) sample is a subset of 

the RECS. Household demographic characteristics reported in the RTECS publication are collected during the RECS 

personal interview. 

Residential heating oil price: The price charged for home delivery of No. 2 heating oil, exclusive of any discounts such as 

those for prompt cash payment. Prices do not include taxes paid bythe consumer. 

Residential propane price: The "bulk keep full" price for home delivery of consumer-grade propane intended for use in 

space heating, cooking, or hot water heaters in residences. 

Residential sector: An energy-consuming sector that consists of living quarters for private households. Common uses of 

energy associated with this sector include space heating, water heating, air conditioning, lighting, refrigeration, cooking, 

and running a variety of other appliances. The residential sector excludes institutional living quarters. Note: Various EIA 

programs differ insectoral coverage. Clickherefor further information on the variations of the residential sector used by EIA 

systems. 

Residential type central air conditioner: There are four basic parts to a residential central air-conditioning system (1) a 

condensing unit, (2) a cooling coil, (3) ductwork, and (4) a control mechanism such as a thermostat. There are two basic 

configurations of residential central systems (1) a "split system" where the condensing unit is located outside and the other 

components are inside, and (2) a packaged-terminal air-encased in one unit and is usuallyfound in a "utilitycloset." 

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Residential vehicles: Motorized vehicles used by U.S. households for personal transportation. Excluded are motorcycles, 

mopeds, large trucks, and buses. Included are automobiles, station wagons, passenger vans, cargo vans, motor homes, 

pickup trucks, and jeeps or similar vehicles. In order to be included (in the ElAsurvey), vehicles must be (1) owned by 

members of the household, or (2) company cars not owned by household members but regularly available to household 

members for their personal use and ordinarily kept at home, or (3) rented or leased for 1 month or more. 

Residential/commercial (consumer category): Housing units, wholesale or retail businesses (except coal wholesale 

dealers); health institutions (hospitals, social and educational institutions (schools and universities); and Federal, state, 

and local governments (military installations, prisons, office buildings, etc.). Excludes shipments to Federal power projects, 

such as TVA, and rural electrification cooperatives, power districts, and state power projects. 

Residual fuel oil: A general classification for the heavier oils, known as No. 5 and No. 6 fuel oils, that remain after the 

distillate fuel oils and lighter hydrocarbons are distilled away in refinery operations. It conforms to ASTM Specifications D 

396 and D 975and Federal Specification W-F-815C. No. 5, a residual fuel oil of medium viscosity, is also known as Navy 

Special and is defined in Military Specification MIL-F-859E, including Amendment 2 (NATO Symbol F-770). It is used in 

steam-powered vessels in government service and inshore powerplants. No. 6 fuel oil includes Bunker C fuel oil and is 

used for the production of electric power, space heating, vessel bunkering, and various industrial purposes. 

Residue gas: Natural gas from which natural gas processing plant liquid products and, in some cases, nonhydrocarbon 

components have been extracted. 

Residuum: Residue from crude oil after distilling off all but the heaviest components, with a boiling range greater than 

1,000 degrees Fahrenheit. 

Resources (Coal) : Naturally occurring concentrations or deposits of coal in the Earth's crust, in such forms and amounts 

that economic extraction is currently or potentially feasible. 

Respondent: A com pany or individual who completes and returns a report or surveyfornn. 

Restoration time: The time when the major portion of the interrupted load has been restored and the emergency is 

considered to be ended. However, some of the loads interrupted may not have been restored due to local problems. 

Restricted-universe census: This is the complete enumeration of data from a specifically defined subset of entities 

including, for example, those that exceed a given level of sales or generator nameplate capacity. 

Restructuring: The process of replacing a monopoly system of electric utilities with competing sellers, allowing individual 

retail customers to choose their electricity supplier but still receive delivery over the power lines of the local utility. It includes 

the reconfiguration of the vertically-integrated electric utility. 

Retail motor gasoline prices: Motor gasoline prices calculated each month by the Bureau of Labor Statistics (BLS) in 

conjunction with the construction of the Consumer Price Index. 

Retail sales (electric): Sales made directly to the customer that consumes the energy product. Retail wheeling: The 

process of moving electric power from a point of generation across third-party-owned transmission and distribution 

systems to a retail customer. 

Retailer: Afirm (other than a refiner, reseller, or reseller/retailer) that carries on the trade or business of purchasing refined 

petroleum products and reselling them to ultimate consumers without substantially changing their form. 

Retained earnings: The balance, either debit or credit, of appropriated or unappropriated retained earnings of the utility 

department arising from earnings. 

Retire from service: Avehicle is retired from service if that vehicle is placed out of service and there are no future plans to 

return that vehicle to service. 

Retired hydropower plant sites: The site of a plant that formerly produced electrical or mechanical power but is now out of 

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service. Includes plants that have been abandoned, damaged byflood or fire, inundated by new reservoirs, or dismantled. 

Return on common equity: The net income less preferred stock dividends, divided by the average common stock equity. 

Return on common stock equity: An equity's earnings available for common stockholders calculated as a percentage of 

its common equity capital. 

Revenue - (electricity): The total amount of money received by an entityfrom sales of its products and/or services; gains 

from the sales or exchanges of assets, interest, and dividends earned on investments; and other increases in the owner's 

equity, except those arising from capital adjustments. 

Revenue requirement: The total revenue that the utility is authorized an opportunityto recover, which includes operating 

expenses and a reasonable return on rate base. 

Reversible turbine: A hydraulic turbine, normally installed in a pumped-storage plant, which can be used alternativelyas a 

pump or as an engine, turbine, water wheel, or other apparatus that drives an electrical generator. 

Revisions and additions (gross change in reserves): The difference (plus or minus) between the year-end reserves plus 

production for a given year and the year-end reserves for the previous year. 

RFG: SeeReformulated Gasoline. 

Ribbon silicon: Crystalline silicon that is used in photovoltaic cells. Ribbon silicon is fabricated by a variety of solidification 

(crystallization) methods that withdraw thin silicon sheets from pools of relatively pure molten silicon. 

Right-of-way: The land and legal right to use and service the land along which a transmission line is located. 

Transmission line right-of-way is usually acquired in widths that varywith the kilovolt (k ) size of the line. 

Right-of-way (electric): A corridor of land on which electric lines may be located. The Transmission Owner may own the 

land in fee, own an easement, or have certain franchise, prescription, or license rights to construct and maintain lines. See 

NERC definition. 

Rip rap: Cobblestone or coarsely broken rock used for protection against erosion of embankment or gully. 

River (method of transportation to consumers - coal): Shipments of coal moved to consumers via river by barge. 

Shipments to Great Lakes coal loading docks or Tidewater pier or coastal points are not included. 

Road oil: Any heavy petroleum oil, including residual asphaltic oil used as a dust palliative and surface treatment on roads 

and highways. It is generally produced in sixgrades, f , the most liquid, to 5, the most viscous. 

Rodlet or GAD basket: An open garbage and debris (GAD) basket that may have contain pieces of fuel rods, disassembled 

fuel rods, and other fuel and nonfuel components. 

Roll front: Atype of uranium deposition localized as a roll or interface separating an oxidized interior from a reduced 

exterior. The reduced side of this interface is significantly enriched in uranium. 

Roof (coal): The rock immediately above a coal seam. The roof is com monly a shale, often carbonaceous and softer than 

rocks higher up in the roof strata. 

Roof insulation: Insulating materials placed underneath the roof or on the roof (building). 

Roof or ceiling insulation: A building shell conservation feature consisting of insulation placed in the roof (below the 

waterproofing layer) or in the ceiling of the top floor in the building. 

Roof or ceiling insulation, insulation in exterior walls: Any material that when placed between the interior surface of the 

building and the exterior surface of the building, reduces the rate of heat loss to the environment or heat gain from the 

environment. Roof or ceiling insulation refers to insulation placed in the roof or ceiling of the top occupied floor in the 

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building. Wall insulation refers to insulation placed between the exterior and interior walls of the building. 

Roof pond: A solar energy collection device consisting of containers of water located on a roof that absorb solar energy 

during the day so that the heat can be used at night or that cools a building by evaporation at night. 

Room air conditioner: Air-conditioning units that typicallyfit into the window or wall and are designed to cool only one room. 

Room heater burning gas, oil, and kerosene: Any of the following heating equipment: circulating heaters, convectors, 

radiant gas heaters, space heaters, or other nonportable room heaters that mayor may not be connected to a flue, vent, or 

chim ney. 

Room-and-pillar mining: The most common method of underground mining in which the mine roof is supported mainly by 

coal pillars left at regular intervals. Rooms are places where the coal is mined; pillars are areas of coal left between the 

rooms. Room-and-pillar mining is done either by conventional or continuous mining. 

Rotary rig: A machine used for drilling wells that employs a rotating tube attached to a bit for boring holes through rock. 

Round test mesh: A sieving screen with round holes, the dimensions of which are of specific sizes to allow certain sizes of 

coal to pass through while retaining other sizes. 

Roundwood: Wood cut specifically for use as a fuel. 

Royalty: A contractual arrangement providing a mineral interest that gives the owner a right to a fractional share of 

production or proceeds there from, that does not contain rights and obligations of operating a mineral property, and that is 

normally free and clear of exploration, developmental and operating costs, except production taxes. 

Royalty cost: Ashare of the profit or product reserved bythe grantor of a mining lease, such as a royalt lessee. 

Royalty interest: An interest in a mineral property provided through a royalty contract. 

Royalty interest (including overriding royalty): These interests entitle their owner(s) to a share of the mineral production 

from a property or to a share of the proceeds there from. They do not contain the rights and obligations of operating the 

property and normally do not bear any of the costs of exploration, development, and operation of the property. 

RSE: Relative Standard Error 

Rulemaking (regulations): The authority delegated to administrative agencies by Congress or State legislative bodies to 

make rules that have the force of law. Frequently tatutory laws that express broad terms of a policy are implemented more 

specifically by administrative rules, regulations, and practices. 

Run off: That portion of the precipitation that flows over the land surface and ultimately reaches streams to complete the 

water cycle. Melting snow is an important source of this water as well as all amounts of surface water that move to streams 

or rivers through any given area of a drainage basin. 

Run-of-mine coal: Coal as it comes from the mine prior to screening or any other treatment. 

Run-of-river hydroelectric plant: A low-head plant using the flow of a stream as it occurs and having little or no reservoir 

capacity for storage. 

Running and quick-start capability: The net capability of generating units that carry load or have quick-start capability. In 

general, quick-start capability refers to generating units that can be available for load within a 30-minute period. 

Rural Electrification Administration (REA): A lending agency of the U.S. Department of Agriculture, the REA makes selfliquidating loans to qualified borrowers to finance electric and telephone service to rural areas. The REA finances the 

construction and operation of generating plants, electric transmission and distribution lines, or systems for the furnishing of 

initial and continued adequate electric services to persons in rural areas not receiving central station service. 

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RVP: SeeReid Vapor Pressure. 

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U.S. Energy Information 

Administration 

Glossary 

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Search glossary terms: 

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Browse terms related to these fuel groups: alternative fuels coal electricity natural gas nuclear petroleum 

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Salable coal: The shippable product of a coal mine or preparation plant. Depending on customer specifications, salable 

coal may be run-of-mine, crushed-and-screened (sized) coal, or the clean coal y Id from a preparation plant. 

Salable natural gas: Natural gas marketed under controlled quality conditions. 

Sales: SeeEnergy sales. 

Sales for resale: A type of wholesale sales covering energy supplied to other electric utilities, cooperatives, municipalities, 

and Federal and state electric agencies for resale to ultimate consumers. 

Sales for resale (electric): Aty lesale sales covering energy supplied to other electric utilities, cooperatives, 

municipalities, and Federal and state electric agencies for resale to ultimate consumers. FERC definition 

Sales to end users: Sales made directly to the consumer of the product. Includes bulk consumers, such as agriculture, 

industry, and utilities, as well as residential and commercial consumers. 

Sales type: Sales categories of sales to end-users and sales for resale. 

Sales volume (coal): The reported output from Federal and/or Indian lands, the basis of royalties. It is apprwdmately 

equivalent to production, which includes coal sold, and coal added to stockpiles. 

Salt dome: A domical arch (anticline) of sedimentary rock beneath the earth's surface in which the layers bend downward 

in opposite directions from the crest and that has a mass of rock salt as its core. 

Salt gradient solar ponds: These consist of three main layers. The top layer is near ambient and has low salt content. The 

bottom layer is hot, typically 160° F to 212° F (71° C to 100° C), and is very salt . The important gradient zone separates 

these zones. The gradient zone acts as a transparent insulator, permitting the sunlight to be trapped in the hot bottom layer 

(f I heat is withdrawn). This is because the salt gradient, which increases the brine density with depth, 

counteracts the buoyancy effect of the warmer water below (which would otherwise rise to the surface and lose its heat to 

the air). An organic Rankine cycle engine is used to convert the thermal energy to electricity. 

Sample (coal): A representative fraction of a coalbed collected by approved methods, guarded against contamination or 

adulteration, and analyzed to determine the nature; chemical, mineralogic, and (or) petrographic composition; percentage 

or parts-per-million content of specified constituents; heat value; and possibly the reactivity of the coal or its constituents. 

Schedule: Astatement of the pricing format of electricity and the terms and conditions governing its applications. 

Scheduled outage: The shutdown of a generating unit, transmission line, or other facility for inspection or maintenance, in 

accordance with an advance schedule. 

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Scheduling coordinators: Entities certified bythe Federal Energy Regulatory Commission (FERC) that act on behalf of 

generators, supply aggregators (wholesale marketers), retailers, and customers to schedule the distribution of electricity. 

Scoop loading: An underground loading method by which coal is removed from the working face by a tractor unit equipped 

with a hydraulically operated bucket attached to the front; also called a front-end loader. 

Screenings: The undersized coal f , usually one-half inch or smaller. 

Seam: Abed of coal lying between a roof and floor. Equivalent term to bed, commonly used by industry. 

Seasonal energy efficiency ratio (SEER): Ratio of the cooling output divided by the power consumption. It is the Btu of 

cooling output during its normal annual usage divided bythe total electric energy input in watt hours during the same 

period. This is a measure of the cooling performance for rating central air conditioners and central heat pumps. The 

appliance standards required a minimum SEER of 10 for split-system central air conditioners and for split-system central 

heat pumps in 1992. (The average heat pump or central air conditioner sold in 1986 had an SEER of about 9.) 

Seasonal pricing: A s pecial electric rate feature under which the price per unit of energy depends on the season of the 

year. 

Seasonal rates: Different seasons of the year are structured into an electric rate schedule whereby an electric utility 

provides service to consumers at different rates. The electric rate schedule usually takes into account demand based on 

weather and other factors. 

Seasonal units: Housing units intended for occupancy at only certain seasons of the year. Seasonal units include units 

intended onlyfor recreational use, such as beach cottages and hunting cabins. It is not likelythat this type of unit will be the 

usual residence for a household, because it may not be fit for living quarters for more than half of the year. 

Seasoned wood: Wood, used for fuel, that has been air dried so that it contains 15 to 20 percent moisture content (wet 

basis). 

Secondary heating equipment: Space-heating equipment used less often than the main space-heating equipment. 

Secondary heating fuel: Fuels used in secondary space-heating equipment. 

Sector: See Energy-use sectors 

Securitization: A proposal for issuing bonds that would be used to buy down existing power contracts or other obligations. 

The bonds would be repaid bydesignating a portion of future customer bill payments. Customer bills would be lowered, 

since the cost of bond payments would be less than the power contract costs that would be avoided. 

Securitize: To aggregate contracts into one pool, which then offers shares for sale in the investment market. This strategy 

diversifies project risks from what theywould be if each project were financed individually, thereby reducing the cost of 

financing. 

SEER: See Seasonal Energy Efficiency Ratio 

Selective absorber: A solar absorber surface that has high absorptance at wavelengths corresponding to that of the solar 

spectrum and low emittance in the infrared range. 

Self-Generator: A plant whose primary product is not electric power, but does generate electricity for its own use or for sale 

on the grid; for example, industrial combined heat and power plants. 

Seller type: Categories of major refiners and other refiners and gas plant operators. 

Semianthracite: See Anthracite 

Semiconductor: Any material that has a limited capacityfor conducting an electric current. Certain semiconductors, 

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including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the 

photovoltaic conversion process. 

Separate metering: Measurement of electricity or natural gas consumption in a building using a separate meter for each of 

several tenants or establishments in the building. 

Separative work unit (SWU): The standard measure of enrichment services. The effort expended in separating a mass F 

of feed of assay xf into a mass P of product assayxp and waste of mass W and assay xw is expressed in terms of the 

number of separative work units needed, given by the expression SWU = WV(xw) + PV(x ) - FV(xf), whereV(x) is the "value 

function," defined as V(x) = (1 - 2x) 1n((1 - x)/x). 

Septic tank: A tank in which the solid matter of continuously flowing sewage is disintegrated by bacteria. 

Series connection: Away of joining photovoltaic cells by connecting positive leads to negative leads; such a configuration 

increases the voltage. 

Series resistance: Parasitic resistance to current flow in a cell due to mechanisms such as resistance from the bulk of the 

semiconductor material, metallic contacts, and interconnections. 

Service area: The territory in which a utility system or distributor is authorized to provide service to consumers. 

Service provider: See Energy service provider 

Service well: Awell drilled, completed, or converted for the purpose of supporting production in an existing field. Wells of 

this class also are drilled or converted for the following specific purposes: gas injection (natural gas, propane, butane or 

fuel-gas); water injection; steam injection; air injection; salt water disposal; water supply for injection; observation; and 

injection for in-situ combustion. 

SF6: See Sulfur hexafluoride 

Shaft mine: A mine that reaches the coal bed by means of a vertical shaft. 

Shakes/shingles: Flat pieces of weather proof material laid with others in a series of overlapping rows as covering for roofs 

and sometimes the sides of buildings. Shakes are similar to wood shingles, but instead of having a cut and smoothly 

planed surface, shakes have textured grooves and a rough or "split" appearance to give a rustic feeling. 

Shale Gas: Natural gas produced from wells that are open to shale formations. Shale is a fine-grained, sedimentary rock 

composed of mud from flakes of clay minerals and tinyfragments (silt-sized particles) of other materials. The shale acts as 

both the source and the reservoir for the natural gas. See natural gas. 

Shallow pitting: Testing a potential mineral deposit by systematically sinking small shafts into the earth and analyAng the 

material recovered. 

Shell storage capacity: The design capacity of a petroleum storage tank which is always greater than or equal to working 

storage capacity. 

Short circuit: An electric current taking a shorter or different path than intended. 

Short circuit current: The current flowing freely through an external circuit that has no load or resistance; the maximum 

current possible. 

Short purchases: Asingle shipment of fuel or volumes of fuel purchased for deliverywithin 1 year. Spot purchases are 

often made by a user to fulfil a certain portion of energy requirements, to meet unanticipated energy needs, or to take 

advantage of low-f I prices. 

Short term sales: Anyshort-term purchase covering a time period of 2 years or less. Purchases from intrastate pipelines 

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pursuant to Section 311(b) of the NGPA of 1978 are classified as short-term sales, regardless of the stated contract term. 

Short ton: A unit of weight equal to 2,000 pounds. 

Short-term debt or borrowings: Debt securities or borrowings having a maturity of less than one year. 

Short-term purchase: A purchase contract under which all deliveries of materials are scheduled to be completed by the 

end of the first calendar year following the contract-signing year. Deliveries can be made during the contract year, but 

deliveries are not scheduled to occur beyond the first calendar year thereafter. 

Shortwall mining: A form of underground mining that involves the use of a continuous mining machine and movable roof 

supports to shear coal panels 150 to 200 feet wide and more than half a mile long. Although similar to longwall mining, 

shortwall mining is generally more flexible because of the smaller working area. Productivity is lower than with longwall 

mining because the coal is hauled to the mine face by shuttle cars as opposed to conveyors. 

Shrinkage: The volume of natural gas that is transformed into liquid products during processing, primarily at natural gas 

liquids processing plants. 

Shut in: Closed temporarily, wells and mines capable of production maybe shut in for repair, cleaning, in accessibility to a 

market, etc. 

Shut-in royalty: A royalt lessee as compensation for a lessor's loss of income because the lessee has deferred 

production from a property that is known to be capable of producing minerals. Shut in maybe caused by a lack of a ready 

market, by a lack of transportation facilities, or by other reasons. A shut-in royalt le out of future 

production. 

Shutdown date: Month and year of shutdown for fuel discharge and refueling. The date should be the point at which the 

reactor became subcritical. 

SI: International System of Units (Systeme international d'unites) 

SIC: SeeStandard Industrial Classification 

Sidetrack drilling: This is a remedial operation that results in the creation of a new section of well bore for the purpose of 

(1) detouring around junk, (2) redrilling lost holes, or (3) straightening key seats and crooked holes. Directional "side-track" 

wells do not include footage in the common bore that is reported as footage for the original well. 

Siding: An exterior wall covering material made of wood, plastic (including vinyl), or metal. Siding is generally produced in 

the shape of boards and is applied to the outside of a building in overlapping rows. 

Silicon: Asemiconductor material made from silica, purified for photovoltaic applications. 

Silt: Waste from Pennsylvania anthracite preparation plants, consisting of coarse rock fragments containing as much as 30 

percent small-sized coal; sometimes defined as including veryfine coal particles called silt. Its heat value ranges from 8 to 

17 million Btu per short ton. Synonymous with culm. 

Silt, culm, refuse bank, or slurry dam mining: A m ining operation producing coal f I. 

Single crystal silicon: An extremely pure form of crystalline silicon produced by dipping a single crystal seed into a pool of 

molten silicon under high vacuum conditions and slowlywithdrawing a solidifyle crystal boule (rod) of silicon. The 

boule is sawed into thin silicon wafers and fabricated into single-crystal photovoltaic cells. 

Single crystal silicon (Czochralsky): Silicon cells with a well-ordered crystalline structure consisting of one crystal (usually 

obtained by means of the Czochralsky growth technique and involv !icing), composing a module. Ribbon silicon 

is excluded. 

Single purpose project: A hydroelectric project constructed only to generate electricity. 

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Single-circuit line: A transm ission line with one electric circuit. For three-phase supply, a single circuit requires at least 

three conductors, one per phase. 

Single-family housing unit: See housing structure/housing unit, specifically under Residential Sector heading. 

Sinter: A chem ical sedimentary rock deposited by precipitation from mineral waters, especially siliceous sinter and 

calcareous sinter. 

Site characterization: An onsite investigation at a known or suspected contaminated waste or release site to determine 

the extent and type(s) of contamination. 

Site energy: The Btu value of energy at the point it enters the home, sometimes referred to as "delivered" energy. The site 

value of energy is used for all f Is, including electricity. 

Site energy consumption: The Btu value of energy at the point it enters the home, building, or establishment, sometimes 

referred to as "delivered" energy. 

Site-specific information DSM program assistance: ADSM (demand-side management) assistance program that 

provides guidance on energy efficiency and load management options tailored to a particular customer's facility, it often 

involves an on-site inspection of the customer facility to identify cost-effective DSM actions that could be taken. They include 

audits, engineering design calculations on information provided about the building, and technical assistance to architects 

and engineers who design new facilities. 

Slope mine: Amine that reaches the coal bed by means of an inclined opening. 

Slot: A physical position in a rack in a storage pool that is intended to be occupied by an intact assembly or equivalent (that 

is, a canister or an assembly skeleton). 

Sludge: Adense, slushy, liquid-to-semifluid product that accumulates as an end result of an industrial or technological 

process designed to purify a substance. Industrial sludges are produced from the processing of energy-related raw 

materials, chemical products, water, mined ores, sewerage, and other natural and man-made products. Sludges can also 

form from natural processes, such as the run off produced by rain fall, and accumulate on the bottom of bogs, streams, 

lakes, and tidelands. 

Slurry: Aviscous liquid with a high solids content. 

Slurry dam: A repositoryfor the silt or culm from a preparation plant. 

Small pickup truck: A pickup truck weighing under 4,500 lbs GVW. 

Small power producer (SPP): Under the Public Utility Regulatory Policies Act (PURPA), a small power production facility (or 

small power producer) generates electricity using waste, renewable (biomass, conventional hydroelectric, wind and solar, 

and geothermal) energy as a primary energy source. Fossil f Is can be used, but renewable resource must provide at 

least 75 percent of the total energy input. (See Code of Federal Regulations, Title 18, Part 292.) 

SNG: See Synthetic Natural Gas 

SO2: See Sulfur Dioxide. 

Sodium lights: Atype of high intensity discharge light that has the most lumens per watt of any light source. 

Sodium silicate: A grey-white powder soluble in alkali and water, insoluble in alcohol and acid. Used to fireproof textiles, in 

petroleum refining and corrugated paperboard manufacture, and as an egg preservative. Also referred to as liquid gas, 

silicate of soda, sodium metasilicate, soluble glass, and water glass. 

Sodium tripolyphosphate: Awhite powder used for water softening and as a food additive and texturizer. 

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Solar cell: See Photovoltaic cell 

Solar constant: The average amount of solar radiation that reaches the earth's upper atmosphere on a surface 

perpendicular to the sun's rays; equal to 1353 Watts per square meter or 492 Btu per square foot. 

Solar cooling: The use of solar thermal energy or solar electricity to power a cooling appliance. There are five basic types of 

solar cooling technologies absorption cooling, which can use solar thermal energy to vaporize the refrigerant; desiccant 

cooling, which can use solar thermal energy to regenerate (dry) the desiccant; vapor compression cooling, which can use 

solar thermal energy to operate a Rankine-cycle heat engine; and evaporative coolers ("swamp" coolers), and heat-pumps 

and air conditioners that can by powered by solar photovoltaic systems. 

Solar declination: The apparent angle of the sun north or south of the earth's equatorial plane. The earth's rotation on its 

axis causes a daily change in the declination. 

Solar dish: See Parabolic dish 

Solar energy: The radiant energy of the sun, which can be converted into other forms of energy, such as heat or electricity. 

Solar pond: A body of water that contains brackish (highly saline) water that forms layers of differing salinity (stratifies) that 

absorb and trap solar energy. Solar ponds can be used to provide heat for industrial or agricultural processes, building 

heating and cooling, and to generate electricity. 

Solar power tower: A solar energy conversion system that uses a large field of independently adjustable 

mirrors(heliostats) to focus solar rays on a near single point atop a fixed tower (receiver). The concentrated energy may be 

used to directly heat the working fluid of a Rankine cycle engine or to heat an intermediary thermal storage medium (such 

as a molten salt). 

Solar radiation: A general term for the visible and near visible (ultraviolet and near-infrared) electromagnetic radiation that 

is emitted by the sun. It has a spectral, or wavelength, distribution that corresponds to different energy levels; short 

wavelength radiation has a higher energy than long-wavelength radiation. 

Solar spectrum: The total distribution of electromagnetic radiation emanating from the sun. The different regions of the 

solar spectrum are described by their wavelength range. The visible region extends from about 390 to 780 nanometers (a 

nanometer is one billionth of one meter). About 99 percent of solar radiation is contained in a wavelength region from 300 

nm (ultraviolet) to 3,000 nm (near-infrared). The combined radiation in the wavelength region from280 nm to 4,000 nm is 

called the broadband, or total, solar radiation. 

Solar thermal collector: A device designed to receive solar radiation and convert it to thermal energy. Normally, a solar 

thermal collector includes a frame, glazing, and an absorber, together with appropriate insulation. The heat collected by the 

solar collector may be used immediately or stored for later use. Solar collectors are used for space heating; domestic hot 

water heating; and heating swimming pools, hot tubs, or spas. 

Solar thermal collector, high temperature: A collector that generally operates at tern peratures above 180 degrees 

Fahrenheit. 

Solar thermal collector, low-temperature: A collector that generally operates at temperatures below 110 degrees 

Fahrenheit. T Ily lazing or insulation and is made of plastic or rubber, although some are made of metal. 

Solar thermal collector, medium-temperature: A collector that generally operates at tern peratures of 140 degrees F to180 

degrees Fahrenheit, but can also operate at temperatures as low as 110 degrees Fahrenheit. Typically 

lazings, a metal f , a metal absorption panel with integral flow channels or attached tubing (liquid collector) or with 

integral ducting (air collector) and insulation on the sides and back of the panel. 

Solar thermal collector, special: An evacuated tube collector or a concentrating (focusing) collector. Special collectors 

operate in the temperature range from just above ambient temperature (low concentration for pool heating) to several 

hundred degrees Fahrenheit (high concentration for air conditioning and specialized industrial processes). 

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Solar thermal panels: A system that actively concentrates thermal energy from the sun by means of solar collector panels. 

The panels typically consist of fat, sun-oriented boxes with transparent covers, containing water tubes of air baffles under a 

blackened heat absorbent panel. The energy is usually used for space heating, for water heating, and for heating 

swimming pools. 

Solar thermal parabolic dishes: A solar thermal technology that uses a modular mirror system that approximates a 

parabola and incorporates two-axis tracking to focus the sunlight onto receivers located at the focal point of each dish. The 

mirror system typically is made from a number of mirror facets, either glass or polymer mirror, or can consist of a single 

stretched membrane using a polymer mirror. The concentrated sunlight may be used directly by a Stirling, Rankine, or 

Brayton cycle heat engine at the focal point of the receiver or to heat a working fluid that is piped to a central engine. The 

primary applications include remote electrification, water pumping, and grid-connected generation. 

Solar trough or solar parabolic trough: See Parabolic trough 

Source material: The term "source material "means (1) uranium, thorium, or any other material that is determined by the 

Atomic Energy Commission pursuant to the provisions of section 61 of the Atomic EnergyAct of 1954, as amended, to be 

source material; or (2) ores containing one or more of the foregoing materials, in such concentration as the Commission 

may by regulation determine from time to time. 

Space heating: The use of energyto generate heat for warmth in housing units using space-heating equipment. The 

equipment could be the main space-heating equipment or secondary space-heating equipment. It does not include the use 

of energy to operate appliances (such as lights, televisions, and refrigerators) that give off heat as a byproduct. 

Spark spread: A measurement of the difference between the price that a generator can obtain from selling one megawatt 

hour (M ) of electricity and the cost of the natural gas needed to generate the MWh of electricity. Spark spread is a 

measure of potential profit for generating electricity on a particular day. 

A key component in the spark spread equation is the heat rate (measure of efficiency) of the generating unit. A common 

measure for heat rate used in the trade press is 7,000 Btu/kWh. This heat rate is broadly representative of the efficiency of 

newer natural gas combined-cycle power plants. (By way of comparison, a plant that has a 50% efficiency rate has a heat 

rate of 6,824 Btu/kWh.) The most efficient natural gas combined-cycle power plants have heat rates somewhat below the 

7,000 Btu/kWh threshold; they can make money even when the implied (breakeven) heat rate is a little below 7,000 Btu/kWh. 

Conversely the level of plant eff the spark spread diminishes—thus, older, less eff t plants have 

lower spark spreads than those with a heat rate of 7,000 Btu/kWh. 

Special collector: An evacuated tube collector or a concentrating (focusing) collector. Special collectors operate in the 

temperature range from just above ambient temperature (low concentration for pool heating) to several hundred degrees 

Fahrenheit (high concentration for air conditioning and specialized industrial processes). 

Special contract rate schedule: An electric rate schedule for an electric service agreement between a utility and another 

party in addition to, or independent of, any standard rate schedule. 

Special naphthas: All f ling range that are used as paint thinners, cleaners, or 

solvents. These products are refined to a specified flash point. Special naphthas include all commercial hexane and 

cleaning solvents conforming to ASTM Specification D1836 and D484, respectively. Naphthas to be blended or marketed as 

motor gasoline or aviation gasoline, or that are to be used as petrochemical and synthetic natural gas (SNG) feedstocks 

are excluded. 

Special nuclear material: The term "special nuclear material" means (1) plutonium, uranium enriched in the isotope 233 

or in the isotope 235, and any other material that the Atomic Energy Com mission, pursuant to the provisions of section 51 of 

the Atomic Energy Act of 1954, as amended, determines to be special nuclear material, but does not include source 

material; or (2) any material artificially enriched by any of the foregoing, but does not include source material. 

Special purpose rate schedule: An electric rate schedule limited in its application to some particular purpose or process 

within one, or more than one, t 

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Specular reflectors: Specular reflectors have mirror like characteristics (the word "specular" is derived from the Greek 

word meaning mirror). The most common materials used for ballasts, the devices that turn on and operate Fluorescent 

tubes, are aluminum and silver. Silver has the highest reflectivity; aluminum has the lowest cost. The materials and shape 

of the reflector are designed to reduce absorption of light within the fixture while delivering light in the desired angular 

pattern. Adding (or retrofitting) specular reflectors to an existing light fixture is frequently implemented as a conservation 

measure. 

Speculative resources (coal): Undiscovered coal in beds that may occur either in known ty is in a favorable 

geologic setting where no discoveries have been made, or in deposits that remain to be recognized. Exploration that 

confirms their existence and better defines their quantity and qualitywould permit their reclassification as identified 

resources. 

Speculative resources (uranium): Uranium in addition to Estimated Additional Resources (EAR) that is thought to exist, 

mostly on the basis of indirect evidence and geological extrapolations, in deposits discoverable with existing exploration 

techniques. The locations of deposits in this category can generally be specified only as being somewhere within given 

regions or geological trends. The existence and size of such deposits are speculative. The estimates in this category are 

less reliable than estimates of EAR. SRcorresponds to DOE's Possible Potential Resources plus Speculative Potential 

Resources categories. 

Spent fuel: Irradiated fuel that is permanently discharged from a reactor. Except for possible reprocessing, this fuel must 

eventually be removed from its temporary storage location at thereactor site and placed in a permanent repository. Spent 

fuel is typically measured either in metric tons of heavy metal (i.e., onlythe heavy metal content of the spent fuel is 

considered) or in metric tons of initial heavy metal (essentially I mass of the fuel before irradiation). The difference 

between these two quantities is the weight of the fission products. 

Spent fuel disassembly hardware: The skeleton of a fuel assembly after the fuel rods have been removed. Generally, SFD 

hardware for PWR assemblies includes guide tubes; instrument tubes, top and bottom nozzles; grid spacers; hold-down 

springs; and attachment components, such as nuts and locking caps. For BWR fuel assemblies, SFD hardware includes 

the top and bottom tie plates, compression springs for individual f I rods, grid spacers, and water rods. 

Spent liquor: The liquid residue left after an industrial process; can be a component of waste materials used as fuel. 

Spillway: A passage for surplus water to flow over or around a dam. 

Spinning reserve: That reserve generating capacity running at a zero load and synchronized to the electric system. 

Split system: When applied to electric air-conditioning equipment, it means a two-part system--an indoor unit and an 

outdoor unit. The indoor unit is an evaporator coil mounted in the indoor circulating air system, and the outdoor unit is an 

air-cooled condensing unit containing an electric motor-driven compressor, a condenser fan, and a fan motor. 

Split tails: Use of one tails assay for transaction of enrichment services and a different tails assay for operation of the 

enrichment plant. This mode of operations tyIly increases the use of uranium, which is relatively inexpensive, while 

decreasing the use of separative work, which is expensive. 

Spontaneous combustion, or self-heating, of coal: A naturally occurring process caused by the oxidation of coal. It is most 

common in low-rank coals and is a potential problem in storing and transporting coal for extended periods. Factors involved 

in spontaneous combustion include the size of the coal (the smaller sizes are more susceptible), the moisture content, and 

the sulfur content. Heat buildup in stored coal can degrade the quality of coal, cause it to smolder, and lead to a fire. 

Spot market (natural gas): A m arket in which natural gas is bought and sold for immediate or very near-term delivery, 

usually for a period of 30 days or less. The transaction does not imply a continuing arrangement between the buyer and the 

seller. A spot market is more likely to develop at a location with numerous pipeline interconnections, thus allowing for a 

large number of buyers and sellers. The Henry Hub in southern Louisiana is the best known spot market for natural gas. 

Spot market (uranium): Buying and selling of uranium for immediate or very near-term delivery. It typically involves 

transactions for delivery of up to 500,000 pounds U308within a year of contract execution. 

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Spot price: The price for a one-time open market transaction for near-term delivery of a specific quantity of product at a 

specific location where the commodity is purchased at current market rates. See alsospotmarket terms associated with 

specific energy types. 

Spot purchases: A single shipment of fuel or volumes of fuel purchased for delivery within 1 year. Spot purchases are often 

made by a user to fulfill a certain portion of energy requirements, to meet unanticipated energy needs, or to take advantage 

of low-fuel prices. 

Spot-market price: Seespot price. 

SPP: SeeSmall Power Producer 

SPR: SeeStrategic Petroleum Reserve. 

SR: Speculative Resources (Coal) 

SR: Speculative Resources (Uranium) 

Stability: The property of a system or element byvirtue of which its output will ultimately attain a steady state. The amount of 

power that can be transferred from one machine to another following a disturbance. The stability of a power system is its 

abilityto develop restoring forces equal to or greater than the disturbing forces so as to maintain a state of equilibrium. 

Stability (electric): The ability of an electric system to maintain a state of equilibrium during normal and abnormal 

conditions or disturbances. NERC definition 

Stabilization lagoon: A s hallow artificial pond used for the treatment of wastewater. Treatment includes removal of solid 

material through sedimentation, the decomposition of organic material by bacteria, and the removal of nutrients by algae. 

Stack: Atall, vertical structure containing one or more flues used to discharge products of combustion to the atmosphere. 

Stand-alone generator: A power source/generator that operates independently of or is not connected to an electric 

transmission and distribution network; used to meet a load(s) physically close to the generator. 

Standard contract: The agreement between the Department of Energy (DOE) and the owners or generators of spent 

nuclear fuel and high-level radioactive waste, under which DOE will make available nuclear waste disposal services to 

those owners and generators. 

Standard fluorescent: Alight bulb made of a glass tube coated on the inside with fluorescent material, which produces 

light by passing electricitythrough mercuryvapor causing the fluorescent coating to glow or fluoresce. 

Standard Industrial Classification (SIC): Replaced with North American Industry Classification System. SeeNAICS. 

Standby charge: A charge for the potential use of a utilityservice, usually done by an agreement with another electric utility 

service. These services include system backup support and other running and quick-start capabilities. 

Standby electricity generation: Involves use of generators during times of high demand on utilities to avoid extra "peakdemand" charges. 

Standby facility: Afacilitythat supports a utilitysystem and is generally running under no-load. It is available to replace or 

supplement a facility normally in service. 

Standby heat loss: Aterm used to describe heat energy lost from a water heater tank. 

Standby service: Support service that is available as needed to supplement a customer, a utility system, or another utility if 

a schedule or an agreement authorizes the transaction. The service is not regularly used. 

Startup test phase of nuclear power plant: A nuclear power plant that has been licensed by the Nuclear Regulatory 

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Commission to operate but is still in the initial testing phase, during which the production of electricity may not be 

continuous. In general, when the electric utility is satisfied with the plant's performance, it formally accepts the plant from the 

manufacturer and places it in commercial operation status. A request is then submitted to the appropriate utility rate 

commission to include the power plant in the rate base calculation. 

Startup/flame stabilization fuel: Any fuel used to initiate or sustain corn bustion or used to stabilize the height of flames 

once combustion is underway. 

State: One of the 50 States, including adjacent outer continental shelf areas, or the District of Columbia. 

State permit/license/mine number: Code assigned to a mining operation bythe state in which the operation is located. 

State severance taxes: Any severance, production, or similar tax, fee, or other levy imposed on the production of crude oil, 

natural gas, or coal by any State, local government acting under authority of State law, or by an Indian tribe recognized as 

eligible for services by the Secretary of the Interior. 

Station (electric): A plant containing prime movers, electric generators, and auxiliary equipment for converting mechanical, 

chemical, and/or nuclear energy into electric energy. 

Station use: Energy that is used to operate an electric generating plant. It includes energy consumed for plant lighting, 

power, and auxiliaryfacilities, regardless of whether the energy is produced at the plant or comes from another source. 

Steam: Water in vapor form; used as the working fluid in steam turbines and heating systems. Also see District heat . 

Steam (purchased): Steam, purchased for use by a refinery, that was not generated from within the refinery complex. 

Steam boiler: Atype of furnace in which fuel is burned and the heat is used to produce steam. 

Steam coal: Coal burned, primarily in boilers, to generate steam for the production of electricity or for process heating 

purposes, or used as a direct source of process heat. Steam coal, also known as thermal coal, refers to all coal not 

classified as coking (or metallurgical) coal. See coal grade. 

Steam electric power plant (conventional): A plant in which the prime mover is a steam turbine. The steam used to drive 

the turbine is produced in a boiler where fossil f Is are burned. 

Steam expenses: The cost of labor, materials, fuel, and other expenses incurred in production of steam for electric 

generation. 

Steam for heating/cooling: Steam produced at a combined heat and power plant for the purpose of heating and/or cooling 

space, such as district heating systems. 

Steam from other sources: Steam purchased, transferred from another department of the utility, or acquired from others 

under a joint-facilityoperating agreement. 

Steam or hot water radiators or baseboards: A distribution system where steam or hot water circulates through cast-iron 

radiators or base boards. Some other types of equipment in the building may be used to produce the steam or hot water or 

it may enter the building already heated as part of a district hot water system. Hot water does not include domestic hot water 

used for cooking and cleaning. 

Steam or hot-water system: Either of two types of a central space-heating system that supplies steam or hot water to 

radiators, convectors, or pipes. The more common type supplies either steam or hot water to conventional radiators, 

baseboard radiators, convectors, heating pipes embedded in the walls or ceilings, or heating coils or equipment that are 

part of a combined heating/ventilating or heating/air-conditioning system. The other ty lies radiant heat through 

pipes that carry hot water and are held in a concrete slab floor. 

Steam transferred-credit: The expenses of producing steam are charged to others or to other utility departments under a 

joint operating arrangement. 

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Steam turbine: A device that converts high-pressure steam, produced in a boiler, into mechanical energythat can then be 

used to produce electricity by forcing blades in a cylinder to rotate and turn a generator shaft. 

Still gas (refinery gas): Any form or mixture of gases produced in refineries by distillation, cracking, reforming, and other 

processes. The principal constituents are methane, ethane, ethylene, normal butane, butylene, propane, propylene, etc. Still 

gas issued as a refineryfuel and a petrochemical feedstock. The conversion factor is 6 million BTU's per fuel oil equivalent 

barrel. 

Stock change: The difference between stocks at the beginning of the reporting period and stocks at the end of the reporting 

period. Note: A negative number indicates a decrease (i.e., a drawdown) in stocks and a positive number indicates an 

increase (i.e., a buildup) in stocks during the reporting period. 

Stocks: Inventories off I stored for future use. 

Storage additions: Volumes of gas injected or otherwise added to underground natural gas reservoirs or liquefied natural 

gas storage. 

Storage agreement: Any contractual arrangement between the responding company and a storage operator under which 

gas was stored for, or gas storage service was provided to, the responding company by the storage operator, irrespective of 

any responding companyownership interest in either the storage facilities or stored gas. 

Storage capacity: The amount of energy an energy storage device or system can store. 

Storage field capacity (underground gas storage): The presently developed maximum capacity of a field (ascollected on 

EIASurvey Form 191) . 

Storage hydroelectric plant: A hydroelectric plant with reservoir storage capacityfor power use. 

Storage site: Spent nuclear fuel storage pool or dry cask storage facility, usually located at the reactor site, as licensed by 

(or proposed to be licensed by) the Nuclear Regulatory Commission (NRC). 

Storage withdrawals: Total volume of gas withdrawn from underground storage or from liquefied natural gas storage over 

a specified amount of time. 

Storm door: Asecond door installed outside or inside a prime door creating an insulating air space. Included are sliding 

glass doors made of double glass or of insulating glass such as thermopane and sliding glass doors with glass or 

Plexiglas placed on either the outside or inside of the door to create an insulating airspace. Not included are doors or 

sliding glass doors covered by plastic sheets or doors with storm window covering on just the glass portion of the door. 

Storm or multiple glazing: A building shell conservation feature consisting of storm windows, stormdoors, or double- or 

triple-paned glass that are placed on the exterior of the building to reduce the rate of heat loss. 

Storm window: Awindow or glazing material placed outside or inside a window creating an insulating air space. Plastic 

material over windows is counted as a storm window if the same plastic material can be used year after year or if the plastic 

is left in place year-round and is in good condition (no holes or tears). If the plastic material must be put up new each year, it 

is not counted as a storm window. It is counted as "plastic coverings." Glass or Plexiglas placed over windows on either the 

interior or exterior side is counted as storm windows. 

Stranded benefits: Benefits associated with regulated retail electric service which maybe at risk under open market retail 

competition. Examples include conservation programs, fuel diversity, reliabilityof supply, and tax revenues based on utility 

revenues. 

Stranded costs: Costs incurred by a utilitywhich may not be recoverable under market-based retail competition. Examples 

include undepreciated generating facilities, deferred costs, and long-term contract costs. 

Strategic Petroleum Reserve (SPR): Petroleum stocks maintained bythe Federal Government for use during periods of 

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major supply interruption. 

Stratigraphic test well: A geologically directed drilling effort to obtain information pertaining to a specific geological 

condition that might lead toward the discovery of an accumulation of hydrocarbons. Such wells are customarily drilled 

without the intention of being completed for hydrocarbon production. This classification also includes tests identified as 

core tests and all t le holes related to hydrocarbon exploration. 

Stratosphere: The region of the upper atmosphere extending from the tropopause (8 to 15 kilometers altitude) to about 50 

kilometers. Its thermal structure, which is determined by its radiation balance, is generallyvery stable with low humidity. 

Stream-flow: The rate at which water passes agiven point in a stream, usually expressed in cubic feet per second. 

Strip mine: An open cut in which the over burden is removed from a coal bed prior to the removal of coal. 

Strip mining (surface): A m ethod used on flatter rain to recover coal by m ining long strips successively the material 

excavated from the strip being mined is deposited in the strip previously mined. 

Strip or stripping ratio: The amount of overburden that must be removed to gain access to a unit amount of coal. A 

stripping ratio maybe expressed as (1) thickness of overburden to thickness of coal, (2) volume of overburden to volume 

coal, (3) weight of overburden to weight of coal, or (4) cubic yards of overburden to tons of coal. A stripping ratio commonly is 

used to express the maximum thickness, volume, or weight of overburden that can be profitably removed to obtain a unit 

amount of coal. 

Stripper well: An oil or gas well that produces at relatively low rates. For oil, stripper production is usually defined as 

production rates of between 5 and 15 barrels of oil per day. Stripper gas production would generally be anything less than 

60 thousand cubic feet per day. 

Styrene: A colorless, toxic liquid with a strong aromatic aroma. Insoluble in water, soluble in alcohol and ether; polymerizes 

rapidly, can become explosive. Used to make poly lymers, polystyrene plastics, and rubber. 

Subbituminous coal: A coal whose properties range from those of lignite to those of bituminous coal and used primarily as 

fuel for steam-electric power generation. It maybe dull, dark brown to black, soft and crumbly, at the lower end of the range, 

to bright, jetblack, hard, and relatively strong, at the upper end. Subbituminous coal contains 20 to 30 percent inherent 

moisture byweight. The heat content of subbituminous coal ranges from 17 to 24 million Btu per ton on a moist, m ineralmatter-f . The heat content of subbituminous coal consumed in the United States averages 17 to 18 million Btu per 

ton, on the as-received basis (i.e., containing both inherent moisture and mineral matter). 

Subcompact/compact passenger car: A passenger car containing less than 109 cubic feet of interior passenger and 

luggage volume. 

Subdivision: A prescribed portion of a given State or other geographical region. 

Submetered data: End-use consumption data obtained for individual appliances when a recording device has been 

attached to the appliance to measure the amount of energy consumed bythe appliance. 

Subsidiary: An entity directly or indirectly controlled by a parent company which owns 50% or more of its voting stock. 

Substation: Facility equipment that switches, changes, or regulates electric voltage. 

Subtransmission: Aset of transmission lines of voltages between transmission voltages and distribution voltages. 

Generally, lines in the voltage range of 69 kVto 138 kV. 

Sulfur: Ayellowish nonmetallic element, sometimes known as "brimstone." It is present at various levels of concentration 

in manyfossil f Is whose combustion releases sulf Ito the environment. Some 

of the most commonly used fossil f Is are categorized according to their sulf , with lower sulf Is usually 

selling at a higher price. Note: No.2 Distillate fuel is currently reported as having either a 0.05 percent or lower sulf level 

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for on-highway vehicle use or a greater than 0.05 percent sulfur level for of highway use, home heating oil, and commercial 

and industrial uses. Residual fuel, regardless of use, is classified as having either no more than 1 percent sulfur or greater 

than 1 percent sulf . Coal is also classified as being low- sulfur at concentrations of 1 percent or less or high-sulf 

Sulfur dioxide (SO2): A toxic, irritating, colorless gas soluble in water, alcohol, and ether. Used as a chemical intermediate, 

in paper pulping and ore refining, and as a solvent. 

Sulfur hexafluoride (SF6): A colorless gas soluble in alcohol and ether, and slightly less soluble in water. It is used as a 

dielectric in electronics. It possesses the highest 100-war Global Warming Potential of any gas (23,900). 

Sulfur oxides (SOx): Compounds containing sulfur and oxygen, such as sulf (502) and sulf (SO3). 

Summer and winter peaking: Having the annual peak demand reached both during the summer months (May through 

October) and during the winter months (November through April). 

Sunk cost: Part of the capital costs actually incurred up to the date of reserves estimation minus depreciation and 

amortization expenses. Items such as exploration costs, land acquisition costs, and costs of financing can be included. 

Superconductivity: The abrupt and large increase in electrical conductivity exhibited bysome metals as the temperature 

approaches absolute zero. 

Supervisory Control and Data Acquisition (electric): A system of remote control and telemetry used to monitor and control 

the transmission system. NERC definition 

Supplemental gas: Any gaseous substance introduced into or commingled with natural gas that increased the volume 

available for disposition. Such substances include, but are not limited to, propane-air, refinery gas, coke-oven gas, still gas, 

manufactured gas, biomass gas, or air or inerts added for Btu stabilization. 

Supplemental gaseous fuels supplies: Synthetic natural gas, propane-air, coke oven gas, refinery gas, biomass gas, air 

injected for Btu stabilization, and manufactured gas commingled and distributed with natural gas. 

Supply: The components of petroleum supply are field production, refinery production, imports, and net receipts when 

calculated on a PAD District basis. 

Supply source: Maybe a single completion, a single well, a single field with one or more reservoirs, several fields under a 

single gas-purchase contract, miscellaneous fields, a processing plant, or a field area; provided, however, that the 

geographic area encompassed by a single supply source may not be larger than the state in which the reserves are 

reported. 

Supply, petroleum: A set of categories used to account for how crude oil and petroleum products are transferred, 

distributed, or placed into the supply stream. The categories include field production, refinery production, and imports. Net 

receipts are also included on a Petroleum Administration for Defense(PAD) District basis to account for shipments of crude 

oil and petroleum products across districts. 

Support equipment and facilities: These include, but are not limited to, seismic equipment, drilling equipment, 

construction and grading equipment, vehicles, repair shops, warehouses, supply points, camps, and division, district, or 

field offices. 

Supporting structure: The main supporting unit (usually a pole or tower) for transmission line conductors, insulators, and 

other auxiliary line equipment. 

Surface drilling expenses (uranium): These include drilling, drilling roads, site preparation, geological and other technical 

support, sampling, and drill-hole logging costs. 

Surface mine: A coal-producing mine that is usuallywithin a few hundred feet of the surface. Earth above or around the 

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coal (overburden) is removed to expose the coalbed, which is then mined with surface excavation equipment, such as 

draglines, powers hovels, bulldozers, loaders, and augers. It may also be known as an area, contour, open-pit, strip, or 

auger mine. 

Surface mining equipment: 

• An Auger machine is a large, horizontal drill, generally3 feet or more in diameter and up to about 100 feet long. It can 

remove coal at a rate of more than 25 tons per minute. 

• A bucket-wheel excavator is a continuous digging machine equipped with a broom on which is mounted a rotating 

wheel with buckets along its edge. The buckets scoop up material, then empty onto a conveyor leading to a spoil 

bank. It is best suited for removing overburden that does not require blasting. This excavator is not widely used in the 

United States. 

• A bulldozer is a tractor with a movable steel blade mounted on the front. It can be used to remove overburden that 

needs little or no blasting. 

• A carryall scraper (or pan scraper) is a self-loading machine, usually self-propelled, with a scraper-like retractable 

bottom. It is used to excavate and haul overburden. 

• A continuous surface miner, used in some lignite mines, is equipped with crawlers, a rotating cutting head, and a 

conveyor. It travels over the bed, excavating a swath up to 13 feet wide and 2 feet deep. 

• Adragline excavator removes overburden to expose the coal by means of a scoop bucket that is suspended from a 

long boom. The dragline digs by pulling the bucket toward the machine by means of a wire rope. 

• Awalking dragline is equipped with large outrigger platforms, or walking beams, instead of crawler tracks. It "walks" 

bythe alternate movement of the walking beams. 

• Adrilling rig is used to determine the amount and type of overburden overlying a coal deposit and the extent of the 

deposit, to delineate major geologic features, and to drill holes for explosives to fragment the overburden for easier 

removal. 

• Afront-end loader is a tractor with a digging bucket mounted and operated on the front. It is often used to remove 

overburden in contour mining and to load coal. 

• An hydraulic shovel excavates and loads by means of a bucket attached to a rigid arm that is hinged to a broom. 

• A power shovel removes overburden and loads coal by means of a digging bucket mounted at the end of an arm 

suspended from a broom. The shovel digs by pushing the bucket forward and upward. It does not dig below the level 

at which it stands. 

• Athin-seam miner resembles an auger machine but has a drum-t lar cross 

section. 

Surface mining methods: 

• Auger mining recovers coal through the use of a large-diameter drill driven into a coalbed in the side of a surface 

mine pit. It usuallyfollows contour surface mining, particularlywhen the overburden is too costlyto excavate. 

• Area mining is practiced on relativelyflat or gently rolling terrain and recovers coal by mining long strips 

successively, the material excavated from the strip being mined is deposited in the strip pit previously mined. 

• Contour mining is practiced when the coal is mined on hillsides. The mining follows the contour of the hillside until 

the overburden becomes uneconomical to remove. This method creates a shelf, or bench, on the hillside. Several 

variations of contour mining have been developed to control environmental problems. These methods include slope 

reduction (overburden is spread so that the angle of the slope on the hillside is reduced), head-of-hollow fill 

(overburden is placed in narrow V-shaped valleys to control erosion), and block-cut (overburden from current mining 

is backfilled into a previously mined cut). 

• Explosives casting is a technique designed to blast up to 65 percent of the overburden into the mine pit for easier 

removal. It differs from conventional overburden blasting, which onlyfractures the overburden before it is removed by 

excavating equipment. 

• Mountaintop mining, sometimes considered a variation of contour mining, refers to the mining of a coalbed that 

underlies the top of a mountain. The overburden, which is the mountaintop, is completely removed so that all of the 

coal can be recovered. The overburden material is later replaced in the mined-out area. This method leaves large 

plateaus of level land. 

• Open-pit coal mining is essentiallya combination of contour and area mining methods and is used to mine thick, 

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steeply inclined coalbeds. The overburden is removed by power shovels and trucks. 

Surface rights: Fee ownership in surface areas of land. Also used to describe a lessee's right to use as much of the 

surface of the land as may be reasonably necessaryfor the conduct of operations under the lease. 

Surplus energy: Energy generated that is beyond the immediate needs of the producing system. This energy may be 

supplied byspinning reserve and sold on an interruptible basis. 

Suspended rates: New rates that have been accepted for review by a utility commission. When these rates are suspended, 

they do not go into effect for a designated period of time. Charges under the new rate may be refunded after the resolution of 

the rate proceeding. 

Swamp coolers (evaporative coolers): Air-conditioning equipment that removes heat by evaporating water. Evaporative 

cooling techniques are most com m only found in warm, dry climates such as in the Southwest, although they are found 

throughout the country. They usually work by spraying cool water into the air ducts, cooling the air as the spray evaporates. 

Switching station: Facility equipment used to tie together two or more electric circuits through switches. The switches are 

selectively arranged to permit a circuit to be disconnected or to change the electric connection between the circuits. 

SWU: See Separative Work Unit 

Synthetic natural gas (SNG): (Also referred to as substitute natural gas) A manufactured product, chemicallysimilar in 

most respects to natural gas, resulting from the conversion or reforming of hydrocarbons that may easily be substituted for 

or interchanged with pipeline-quality natural gas. 

System (electric): Physically connected generation, transmission, and distribution facilities operated as an integrated unit 

under one central management or operating supervision. 

System (gas): An interconnected network of pipes, valves, meters, storage facilities, and auxiliary equipment used in the 

transportation, storage, and/or distribution of natural gas or commingled natural and supplemental gas. 

System interconnection: A physical connection between two electric systems that permits the transfer of electric energy in 

either direction. 

System operator (electric): An individual at a control center (Balancing Authority, Transmission Operator, Generator 

Operator, Reliability Coordinator) whose responsibility it is to monitor and control that electric system in real time. NERC 

definition 

ABCDEFGHIJKLMNOPQRSTUVWXYZ 

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Glossary 

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T 

T: trillion 1012 

t: tenth 

Tailgate: The outlet of a natural gas processing plant where dry residue gas is delivered or re-delivered for sale or 

transportation. 

Tailings: The remaining portion of a metal-bearing ore consisting of finelyground rock and process liquid after some or all 

of the metal, such as uranium, has been extracted. 

Tall oil: The oily mixture of rosin acids, fatty acids, and other materials obtained by acid treatment of the alkaline liquors 

from the digesting (pulping) of pine wood. 

TAME: SeeTertiary Amyl Methyl Ether. 

Tangible development costs: Costs incurred during the development stage for access, mineral-handling, and support 

facilities having a physical nature. In mining, such costs would include tracks, lighting equipment, ventilation equipment, 

other equipment installed in the mine to facilitate the extraction of minerals, and supporting facilities for housing and care of 

work forces. In the oil and gas industry, tangible development costs would include well equipment (such as casing, tubing, 

pumping equipment, and well heads), as well as field storage tanks and gathering systems. 

Tank farm: An installation used by trunk and gathering pipeline companies, crude oil producers, and terminal operators 

(except refineries) to store crude oil. 

Tanker and barge: Vessels that transport crude oil or petroleum products. Note: Data are reported for movements between 

PAD Districts; from a PAD District to the Panama Canal; or from the Panama Canal to a PAD District. 

Tar sands: Naturallyoccurring bitumen-impregnated sands that yield mixtures of liquid hydrocarbon and that require further 

processing other than mechanical blending before becoming finished petroleum products. 

Tariff: Apublished volume of rate schedules and general terms and conditions under which a product or service will be 

supplied. 

Tax-cost: A deduction (allowance) under U.S. Federal income taxation normally calculated under a formula wherebythe 

adjusted basis of the mineral property is multiplied by a fraction, the numerator of which is the number of units of minerals 

sold during the taxyear and the denominator of which is the estimated number of units of unextracted minerals remaining 

at the end of the taxyear plus the number of units of minerals sold during the taxyear. 

TBA: SeeTertiary Butyl Alcohol 

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Telemetring (electric): The process bywhich measurable electrical quantities from substations and generating stations 

are instantaneously transm itted to the control center, and, bywhich, operating commands from the control center are 

transmitted to the substations and generating stations. NERC definition 

Temperature coefficient (of a solar photovoltaic cell): The amount that the voltage, current, and/or power output of a solar 

cell changes due to a change in the cell temperature. 

Temporarily discharged fuel: Fuel that was irradiated in the previous fuel cycle (cycle N) and not in the following fuel cycle 

(cycle N+1) and that will be irradiated in a subsequent f I cycle. 

Tennessee Valley Authority (TVA): Afederal agency established in 1933 to develop the Tennessee river valley region of 

the southeastern U.S. 

Terawatthour: One trillion watt hours. 

Term agreement: Anywritten or unwritten agreement between two parties in which one party agrees to supply a commodity 

on a continuing basis to a second partyfor a price or for other considerations. 

Terminal location: The physical location of one end of a transmission line segment. 

Terrestrial sequestration: Biotic sequestration of carbon in above- and below-ground biomass and soils. 

Tertiary amyl methyl ether - (CH3)2(C2H5)COCH3: An oxygenate blend stock formed by the catalytic etherification of 

isoamylene with methanol. 

Tertiary butyl alcohol - (CH3)3COH: An alcohol primarily used as a chemical feedstock or a solvent or feedstock, for 

isobutylene production for MTBE (methyl tertiary butyl ether) and produced as a co-product of propylene oxide production or 

by direct hydration of isobutylene. 

Test well contribution: A payment made to the owner of an adjacent or nearby tract who has drilled an exploratory well on 

that tract in exchange for information obtained from the drilling effort. 

the thousandth 

Therm: One hundred thousand (100,000) Btu. 

Thermal: A term used to identify a type of electric generating station, capacity, capability, or output in which the source of 

energyfor the prime mover is heat. 

Thermal conversion factor: Afactor for converting data between physical units of measure (such as barrels, cubic feet, or 

short tons) and thermal units of measure (such as British thermal units, calories, or joules); or for converting data between 

different thermal units of measure. See Btu conversion factor. 

Thermal cracking: A refining process in which heat and pressure are used to break down, rearrange, or combine 

hydrocarbon molecules. Thermal-cracking includes gas oil, visbreaking, fluid coking, delayed coking, and other thermal 

cracking processes (e.g., flexicoking). 

Thermal efficiency: A measure of the efficiency of converting a fuel to energy and useful work; useful work and energy 

output divided by higher heating value of input fuel times 100 (for percent). 

Thermal energy storage: The storage of heat energy during utility off-peak times at night, for use during the next day 

without incurring daytime peak electric rates. 

Thermal limit: The maximum amount of power a transmission line can carry without suffering heat-related deterioration of 

line equipment, particularly conductors. 

Thermal rating (electric): The maximum amount of electrical current that a transmission line or electrical facility can 

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conduct over a specified time period before it sustains permanent damage byoverheating or before it sags to the point that 

it violates public safety requirements. NERC definition 

Thermal resistance (R-Value): This designates the resistance of a material to heat conduction. The greater the R-value the 

larger the number. 

Thermal storage: Storage of heat or heat sinks (coldness) for later heating or cooling. Examples are the storage of solar 

energy for night heating; the storage of summer heat for winter use; the storage of winter ice for space cooling in the 

summer; and the storage of electrically-generated heat or coolness when electricity is less expensive, to be released in 

order to avoid using electricity when the rates are higher. There are four basic types of thermal storage systems: ice 

storage; water storage; storage in rock, soil or other types of solid thermal mass; and storage in other materials, such as 

glycol (antifreeze). 

Thermocouple: Adevice consisting of two dissimilar conductors with their ends connected together. When the two 

junctions are at different temperatures, a small voltage is generated. 

Thermodynamics: Astudyof the transformation of energyfrom one form to another, and its practical application. 

Thermophotovoltaic cell: Adevice where sunlight concentrated onto a absorber heats it to a high temperature, and the 

thermal radiation emitted by the absorber is used as the energy source for a photovoltaic cell that is designed to maximize 

conversion efficiency at the wavelength of the thermal radiation. 

Thermosiphon system: A solar collector system for water heating in which circulation of the collection fluid through the 

storage loop is provided solely bythe temperature and density difference between the hot and cold fluids. 

Thermostat: Adevice that adjusts the amount of heating and cooling produced and/or distributed by automatically 

responding to the temperature in the environment. 

Third-party DSM program sponsor: An energyservice company (ESCO) which promotes a program sponsored by a 

manufacturer or distributor of energy products such as lighting or refrigeration whose goal is to encourage consumers to 

improve energy efficiency, reduce energy costs, change the time of usage, or promote the use of a different energy source. 

Third-party transactions: Third-party transactions are arms-length transactions between non affiliated firms. Producing 

country-to-corn pany transactions are not considered to be third-party transactions. 

Thorium: An element that is a byproduct of the decay of uranium. 

Three-phase power: Power generated and transmitted from generator to load on three conductors. 

Tidewater piers and coastal ports (method of transportation to consumers): Shipments of coal moved to tidewater piers 

and coastal ports for further shipments to consumers via coastal water or ocean. 

Tie line: Atransmission line connecting two or more power systems. 

Tie line (electric): Acircuit connecting two Balancing AuthorityAreas. Also, describes circuits within an individual electrical 

system. NERC definition 

Time clocks or timed switches: Time clocks are automatic controls, which turn lights off and on at pre determined times. 

Time-of-day lock-out or limit: Aspecial electric rate feature under which electricity usage is prohibited or restricted to a 

reduced level at fixed times of the day in return for a reduction in the price per kilowatt hour. 

Time-of-day pricing: Aspecial electric rate feature under which the price per kilowatthour depends on the time of day. 

Time-of-day rate: The rate charged by an electric utility for service to various classes of customers. The rate reflects the 

different costs of providing the service at different times of the day. 

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Timing differences: Differences between the periods in which transactions affect taxable income and the periods in which 

they enter into the determination of pretax accounting income. Timing differences originate in one period and reverse or 

"turn around" in one or more subsequent periods. Some timing differences reduce income taxes that would otherwise be 

payable currently, others increase income taxes that would otherwise be payable currently. 

Tinted or reflective glass or shading films: Types of glass or a shading film applied to glass that, when installed on the 

exterior of a building, reduces the rates of solar penetration into the building. Includes Low E Glass. 

Tipping fee: Price charged to deliver municipal solid waste to a landfill, waste-to-energy facility, or recycling facility. 

Tipple: Acentral facility used in loading coal for transportation by rail or truck. 

Tolling arrangement: Contract arrangement under which a raw material or intermediate product stream from one company 

is delivered to the production facility of another company in exchange for the equivalent volume of finished products and 

payment of a processing fee. 

Toluene (C6H5CH3): Colorless liquid of the aromatic group of petroleum hydrocarbons, made by the catalytic reforming of 

petroleum naphthas containing methyl cyclohexane. A high-octane gasoline-blending agent, solvent, and chemical 

intermediate, and a base for TNT (explosive). 

Ton mile: The product of the distance that freight is hauled, measured in miles, and the weight of the cargo being hauled, 

measured in tons. Thus, moving one ton for one mile generates one ton mile. 

Topping cycle: A boiler produces steam to power a turbine-generator to produce electricity. The steam leaving the turbine 

is used in thermal applications such as space heating and/or cooling or delivered to other end user(s). 

Total discoveries: The sum of extensions, new reservoir discoveries in old fields, and new field discoveries, that occurred 

during the report year. 

Total gas in storage: The sum of base gas and working gas. 

Total liquid hydrocarbon reserves: The sum of crude oil and natural gas liquids reserves volumes. 

Total operated basis: The total reserves or production associated with the wells operated by an individual operator. This is 

also commonly known as the "gross operated" or "8/8ths" basis. 

Total Storage Reid Capacity: The maximum volume of natural gas (including both base and working gas) that can be 

stored in an underground storage facility in accordance with its design specifications, the physical characteristics of the 

reservoir, installed compression equipment, and operating procedures particular to the site. 

Transfer capability: The overall capacity of interregional or international power lines, together with the associated electrical 

system facilities, to transfer power and energy from one electrical system to another. 

Transfer price: The monetary value assigned to products, services, or rights conveyed or exchanged between related 

parties, including those occurring between units of a consolidated entity. 

Transformer: An electrical device for changing the voltage of alternating current. 

Transmission (electric): An interconnected group of lines and associated equipment for the movement or transfer of 

electric energy between points of supply and points at which it is transformed for deliveryto customers or is delivered to 

other electric systems. NERC definition 

Transmission (electric) (verb): The movement or transfer of electric energy over an interconnected group of lines and 

associated equipment between points of supply and points at which it is transformed for delivery to consumers or is 

delivered to other electric systems. Transmission is considered to end when the energy is transformed for distribution to 

the consumer. 

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Transmission and distribution loss: Electric energy lost due to the transmission and distribution of electricity. Much of the 

loss is thermal in nature. 

Transmission circuit: A conductor used to transport electricity from generating stations to load. 

Transmission constraint (electric): A lim itation on one or more transmission elements that maybe reached during 

normal or contingency system operations. NERC definition 

Transmission line: Aset of conductors, insulators, supporting structures, and associated equipment used to move large 

quantities of power at high voltage, usually over long distances between a generating or receiving point and major 

substations or delivery points. 

Transmission line (electric): A system of structures, wires, insulators and associated hardware that carry electric energy 

from one point to another in an electric power system. Lines are operated at relatively high voltages varying from 69 kV up to 

765 kV, and are capable of transmitting large quantities of electricity over long distances. NERC definition 

Transmission network: A system of transmission or distribution lines so cross-connected and operated as to permit 

multiple power supply to any principal point. 

Transmission operator (electric): The entity responsible for the reliability of its localized transmission system, and that 

operates or directs the operations of the transmission facilities. NERC definition 

Transmission owner (electric): The entitythat owns and maintains transmission facilities. NERC definition 

Transmission Service Provider (electric): The entitythat administers the transmission tariff and provides Transmission 

Service to Transmission Customers under applicable transmission service agreements. NERC definition 

Transmission system (electric): An interconnected group of electric transmission lines and associated equipment for 

moving or transferring electric energy in bulk between points of supply and points at which it is transformed for deliveryover 

the distribution system lines to consumers or is delivered to other electric systems. 

Transmission type (engine): The transmission is the part of a vehicle that transmits motive force from the engine to the 

wheels, usually by means of gears for different speeds using either a hydraulic "torque-converter" (automatic) or clutch 

assembly (manual). On front-wheel drive cars, the transmission is often called a "transa)de." Fuel efficiency is usually 

higher with manual rather than automatic transmissions, although modern, computer-controlled automatic transmissions 

can be efficient. 

Transmitting utility: A regulated entity which owns and may construct and maintain wires used to transmit wholesale 

power. It mayor may not handle the power dispatch and coordination functions. It is regulated to provide non-discriminatory 

connections, comparable service, and cost recovery. 

Transport: Movement of natural, synthetic, and/or supplemental gas between points beyond the immediate vicinity of the 

field or plant f (1) for movements through well or field lines to a central point for delivery to a 

pipeline or processing plant within the same state or (2) movements from a city gate point of receipt to consumers through 

distribution mains. 

Transportation agreement: Any contractual agreement for the transportation of natural and/or supplemental gas between 

points for a fee. 

Transportation energy expenditures: SeeVehicle fuel expenditures. 

Transportation sector: An energy-consuming sector that consists of all vehicles whose primary purpose is transporting 

people and/or goods from one physical location to another. Included areautomobiles; trucks; buses; motorcycles; trains, 

subways, and other rail vehicles; aircraft; and ships, barges, and other waterborne vehicles. Vehicles whose primary 

purpose is not transportation (e.g., construction cranes and bulldozers, farming vehicles, and warehouse tractors and fork 

lifts) are classified in the sector of their primary use. 

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Note: Various EIA programs differ in sectoral coverage. See: an explanation of the variations of the transportation sector 

used by ElAsystem(s). 

Transported gas: Natural gas physically delivered to a building by a local utility, but not purchased from that utility. A 

separate transaction is made to purchase the volume of gas, and the utility is paid for the use of its pipeline to deliver the 

gas. Also called "Direct-Purchase Gas," "Spot Market Gas," "Spot Gas," "Gas for the Account of Others", and "Self-Help Gas." 

Transporter: The party or parties, other than buyer or seller, owning the facilities by which gas or LNG is physically 

transferred between buyer and seller. 

Transshipment: A m ethod of ocean transportation whereby s hips off-load their oil cargo to a deep water terminal, floating 

storage facility, temporary storage, or to one or more smaller tankers from which or in which the oil is then transported to a 

market destination. 

Treating plant: A plant designed primarilyto remove undesirable impurities from natural gas to render the gas marketable. 

Trillion Btu: Equivalent to 1,000,000,000,000 or 10 to the 12th power Btu. 

Troposphere: The inner layer of the atmosphere below about 15 kilometers, within which there is normally a steady 

decrease of temperature with increasing altitude. Nearly all clouds form and weather conditions manifest themselves within 

this region. Its thermal structure is caused primarily bythe heating of the earth's surface bysolar radiation, followed by heat 

transfer through turbulent mixing and convection. 

Trough: High-temperature (180+) concentrator with one axis-tracking. 

Trunk line: Amain pipeline. 

Turbine: A machine for generating rotary mechanical power from the energy of a stream of fluid (such as water, steam, or 

hot gas). Turbines convert the kinetic energy of fluids to mechanical energy through the principles of impulse and reaction, 

or a mixture of the two. 

T Iley Authority 

TWh: SeeTerawatthour 

Type of drive (vehicle): Refers to which wheels the engine power is delivered to, the so-called "drive wheels." Rear-wheel 

drive has drive wheels on the rear of the vehicle. Front-wheel drive, a newer technology, has drive wheels on the front of the 

vehicle. Four-wheel drive uses all four wheels as drive wheels and is found mostly on Jeep-like vehicles and trucks, though 

it is becoming increasingly more common on station wagons and vans. 

ABCDEFGHIJKLMNOPQRSTUVWXYZ 

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U 

U.S. refiner acquisition cost of imported crude oil: The average price paid by U.S. refiners for imported, that is, non-U.S., 

crude oil booked into their refineries in accordance with accounting procedures generally accepted and consistently and 

historically applied bythe refiners concerned. The refiner acquisition cost of imported crude oil includes transportation and 

other fees paid bythe refiner. 

U.S.S.R.: SeeUnion of Soviet Socialist Republics (U.S.S.R.). 

U308: SeeUranium oxide. 

UF6: SeeUranium hexaflouride. 

ULCC: Ultra Large Crude Carrier. 

Ultimate customer: A customer that purchases electricityfor its own use and not for resale. 

Ultra-low sulfur diesel (ULSD) fuel: Diesel fuel containing a maximum 15 parts per million (ppm) sulfur. 

Ultraviolet: Electromagnetic radiation in the wavelength range of 4 to 400 nanometers. 

UMTRA: SeeUranium Mill Tailings Radiation Control Act of 1978. 

Unaccounted for (crude oil): Represents the arithmetic difference between the calculated supply and the calculated 

disposition of crude oil. The calculated supply is the sum of crude oil production plus imports minus changes in crude oil 

stocks. The calculated disposition of crude oil is the sum of crude oil input to refineries, crude oil exports, crude oil burned 

as fuel, and crude oil losses. 

Unaccounted for (natural gas): Represents differences between the sum of the components of natural gas supply and the 

sum of components of natural gas disposition. These differences maybe due to quantities lost or to the effects of data 

reporting problems. Reporting problems include differences due to the net result of conversions of flow data metered at 

varying temperatures and pressure bases and converted to a standard temperature and pressure base; the effect of 

variations in company accounting and billing practices; differences between billing cycle and calendar-period time frames; 

and imbalances resulting from the merger of data reporting systems that vary in scope, format, definitions, and type of 

respondents. 

Unbundling: Separating vertically integrated monopoly functions into their corn ponent parts for the purpose of separate 

service offerings. 

Uncompleted wells, equipment, and facilities costs: The costs incurred to (1) drill and equip wells that are not yet 

completed, and (2) acquire or construct equipment and facilities that are not yet completed and installed. 

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Unconsolidated entity: Afirm directly or indirectly controlled by a parent but not consolidated with the parent for purposes of 

financial statements prepared in accordance with generally accepted accounting principles. An unconsolidated entity 

includes anyfirm consolidated with the unconsolidated entityfor purposes of financial statements prepared in accordance 

with generally accepted accounting principles historically and consistently applied. An individual shall be deemed to control 

a firm that is directly or indirectly controlled by him or by his father, mother, spouse, children, or grandchildren. 

Unconventional oil and natural gas production: An umbrella term for oil and natural gas that is produced by means that do 

not meet the criteria for conventional production. SeeConventional oil and natural gas production. Note: What has qualified 

as "unconventional" at any particular time is a complex interactive function of resource characteristics, the available 

exploration and production technologies, the current economic environment, and the scale, f , and duration of 

production from the resource. Perceptions of these factors inevitably change over time and they often differ among users of 

the term. For these reasons, the scope of this term will be expressly stated in any EIA publication that uses it. For example, 

see International Energy Outlook, Table E4for the list it currently uses for unconventional oil and natural gas production. 

Underground gas storage: The use of sub-surface facilities for storing gas that has been transferred from its original 

location. The facilities are usually hollowed-out salt domes, geological reservoirs (depleted oil or gas fields) or waterbearing sands topped by an impermeable cap rock (aquifer). 

Underground gas storage reservoir capacity: Interstate company reservoir capacities are those certificated by the Federal 

Energy Regulatory Commission. Independent producer and intrastate company reservoir capacities are reported as 

developed capacity. 

Underground mine: Amine where coal is produced by tunneling into the earth to the coalbed, which is then mined with 

underground mining equipment such as culling machines and continuous, longwall, and shortwall mining machines. 

Underground mines are classified according to the type of opening used to reach the coal, i.e., drift (level tunnel), slope 

(inclined tunnel), or shaft (vertical tunnel). 

Underground mining equipment: 

• A coal-cutting machine is used in conventional mining to undercut, top cut, or shear the coal face so that coal can 

be fractured easily when blasted. It cuts 9 to 13 feet into the bed. 

• Continuous auger machine is used in mining coalbeds less than 3 feet thick. The auger has a cutting depth of 

about 5 feet and is 20 to 28 inches in diameter. Continuous auger mining usually uses a conveyor belt to haul the 

coal to the surface. 

• Continuous mining machine, used during continuous mining, cuts or rips coal f loads it into shuttle 

cars or conveyors in one operation. It eliminates the use of blasting devices and performs manyfunctions of other 

equipment such as drills, cutting machines, and loaders. Acontinuous mining machine typically has a turning 

"drum" with sharp bits that cut and dig out the coal for 16 to 22 feet before mining stops so that the mined area can 

be supported with roof bolt . This machine can mine coal at the rate of 8 to 15 tons per minute. 

• There are of two types of conveyor systems: 

1. A mainline conveyor, which is usually a permanent installation that carries coal to the surface. 

2. A section conveyor, which connects the working face to the mainline conveyor. 

• Face drill is used in conventional mining to drill shot holes in the coalbed for explosive charges. 

• Loading machine is used in conventional mining to scoop broken coal f load it into a 

shuttle car, which hauls the coal to mine cars or conveyors for delivery to the surface. 

• Longwall mining machine shears coal f long straight coal face (up to about 700 feet) by working back and forth 

across the face under a movable, hydraulic-jack roof-support system. The broken coal is transported by conveyor. 

Longwall machines can mine coal at the rate of 1,000 tons per shift. Mine locomotive, operating on tracks, is used to 

haul mine cars containing coal and other material, and to move personnel in specially designed "mantrip" cars. 

Large locomotives can haul more than 20 tons at a speed of about 10 miles per hour. Most mine locomotives run on 

electricity provided by a trolley wire; some are battery-powered. 

• Ram car or shuttle ram is a rubber-tired haulage vehicle that is unloaded through the use of a movable steel plate 

located at the back of the haulage bed. 

• Roof-bolting machine, or roof bolter, is used to drill holes and place bolts to support the mine roof. Roof bolting 

units can be installed on a continuous mining machine. 

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• Scoop is a rubber-tired haulage vehicle used in thin coalbeds. 

• Shortwall mining machine generally is a continuous-mining machine used with a powered, self-advancing roof 

support system. It shears coal f I face (up to about 150 feet long). The broken coal is hauled by 

shuttle cars to a conveyor belt 

• Shuttle car is a rubber-tired haulage vehicle that is unloaded bya built-in conveyor. 

Underground mining methods: 

• Adrift mine is driven horizontally into coal that is exposed or accessible in a hillside. In a hydraulic mine, highpressure water jets break the coal f ly inclined, thick coalbed that would be difficult to mine with the usual 

underground methods. The coal is then transported to the surface bya system of flumes or by pipeline. Although 

currently not in commercial use in the United States, hydraulic mining is used in western Canada. 

• A punch mine is a type of small drift mine used to recover coal from strip-mine highwalls or from small, otherwise 

uneconomical, coal deposits. Ashaft mine is driven vertically to the coal deposit. Aslope mine is driven at an angle 

to reach the coal deposit. 

• In a room-and-pillar mining system, the most common method, the mine roof, is supported mainly by coal pillars left 

at regular intervals. Rooms are places where the coal is mined; pillars are areas of coal left between the rooms. 

Room-and-pillar mining is done either by 1) conventional mining, which involves a series of operations that require 

cutting the working face of the coalbed so that it breaks easily when blasted with explosives or high-pressure air, 

and then loading the broken coal or 2) continuous mining, in which a continuous mining machine extracts and 

removes coal f . When a section of a mine has been fully developed, additional 

coal is extracted by mining the supportive pillars until the roof caves in; the procedure is called room-and-pillar 

retreat mining. 

• In a longwall mining system, long sections of coal, up to about 700 feet, are removed and no pillars are left to 

support the mined-out areas. The working area is protected bya movable, powered roof support system. The caved 

area (gob) compacts and, after initial subsidence, supports the overlying strata. Longwall mining is used where the 

coalbed is thick and generallyflat, where surface subsidence is acceptable. 

• Ashortwall mining system generally refers to the room-and-pillar mining in which the working face is wider than 

usual but smaller (less than 150 feet) than that in longwall mining. 

Roof support and mine ventilation are paramount in all underground mining operations. Roof bolting is the principal 

method of supporting the mine roof. In roof bolting, long bolts, 2 to 10 feet long with an expansion shell or with resin 

grouting are placed in the mine roof. The bolts reinforce the roof by pulling together rock strata to make a strong 

beam or by fastening weak strata to strong strata. Mine ventilation, accomplished with fans, is essential to supply 

fresh air and to remove gases and dust from the mine. To r the possibility of coal dust explosions, r t is 

sprayed in an underground coal mine. Rock dust is a very fine noncombustible material (pulverized limestone). 

Underground storage: The storage of natural gas in underground reservoirs at a different location from which it was 

produced. 

Underground storage injections: Gas from extraneous sources put into underground storage reservoirs. 

Underground storage withdrawals: Gas removed from underground storage reservoirs. 

Undifferentiated/unspecified reserves and production: Reserves and production that are not separable by FERC 

production areas or by states. Undifferentiated and unspecified reserves consist only of company-owned gas in 

underground storage. 

Undiscovered recoverable reserves (crude oil and natural gas): Those economic resources of crude oil and natural gas, 

yet undiscovered, that are estimated to exist in favorable geologic settings. 

Undiscovered resources (coal): Unspecified bodies of coal surmised to exist on the basis of broad geologic knowledge 

and theory. Undiscovered resources include beds of bituminous coal and anthracite 14 inches or more thick and beds of 

sub bituminous coal and lignite 30 inches or more thick that are presumed to occur in unmapped and unexplored areas to 

depths of 6,000 feet. The speculative and hypothetical resource categories comprise undiscovered resources. 

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Unfilled requirements: Requirements not covered by usage of inventory or supply contracts in existence as of January 1 of 

the survey year. 

Unfinished oils: All oils requiring further processing, except those requiring only mechanical blending. Unfinished oils are 

produced by partial refining of crude oil and include naphthas and lighter oils, kerosene and light gas oils, heavygas oils, 

and residuum. 

Unfractionated streams: Mixtures of unsegregated natural gas liquid components, excluding those in plant condensate. 

This product is extracted from natural gas. 

Unglazed solar collector: A solar thermal collector that has an absorber that does not have a glazed covering. Solar 

swimming pool heater systems usually use unglazed collectors because they circulate relatively large volumes of water 

through the collector and capture nearly 80 percent of the solar energy available. 

Uniform system of accounts: Prescribed financial rules and regulations established bythe Federal Energy Regulatory 

Commission for utilities subject to its jurisdiction under the authority granted by the Federal Power Act. 

Union of Soviet Socialist Republics (U.S.S.R.): Apolitical entity that consisted of 15 constituent republics: Armenia, 

Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latv thuania, Moldova, Russia, Tajikistan, 

Turkmenistan, Ukraine, and Uzbekistan. The U.S.S.R. ceased to exist as of December 31, 1991 

Unit price: Total revenue derived from the sale of product during the reference month divided by the total volume sold; also 

known as the weighted average price. Total revenue should exclude all taxes but include transportation costs that were paid 

as part of the purchase price. 

Unit value, consumption: Total price per specified unit, including all taxes, at the point of consumption. 

Unit value, wellhead: The wellhead sales price, including charges for natural gas plant liquids subsequently removed from 

the gas; gathering and compression charges; and state production, severance, and/or similar charges. 

United States: The 50 States and the District of Columbia. Note: The United States has varying degrees of jurisdiction over 

a number of territories and other political entities outside the 50 States and the District of Columbia, including Puerto Rico, 

the U.S. V Islands, Guam, American Samoa, Johnston Atoll, Midway Islands, Wake Island, and the Northern Mariana 

Islands. EIA data programs may include data from some or all of these areas in U.S. totals. For these programs, data 

products will contain notes explaining the extent of geographic coverage included under the term "United States." 

Unleaded midgrade gasoline: See Gasoline grades. 

Unleaded premium gasoline: See Gasoline grades. 

Unleaded regular gasoline: See Gasoline grades. 

Unprocessed gas: Natural gas that has not gone through a processing plant. 

Unregulated Entity: For the purpose of EIA's data collection effor , entities that do not have a designated franchised 

service area and that do not file forms listed in the Code of Federal Regulations, Title 18, Part 141, are considered 

unregulated entities. This includes qualifying cogenerators, qualify ll power producers, and other generators that are 

not subject to rate regulation, such as independent power producers. 

Unscheduled outage service: Power received by a system from another system to replace power from a generating unit 

forced out of service. 

Uprate: An increase in available electric generating unit power capacity due to a system or equipment modification. An 

uprate is typically a permanent increase in the capacity of a unit. 

Uranium (U): A heavy, naturally radioactive, metallic element (atomic number 92). Its two principally occurring isotopes are 

uranium-235 and uranium-238. Uranium-235 is indispensable to the nuclear industr t is the only isotope existing 

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in nature, to any appreciable extent, that is fissionable by thermal neutrons. Uranium-238 is also important because it 

absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope plutonium-239, which also is 

fissionable bythermal neutrons. 

Uranium concentrate: Aye!low or brown powder obtained by the milling of uranium ore, processing of in situ leach mining 

solutions, or as a byproduct of phosphoric acid production. 

Uranium deposit: Adiscrete concentration of uranium mineralization that is of possible economic interest. 

Uranium endowment: The uranium that is estimated to occur in rock with a grade of at least 0.01 percent U308. The 

estimate of the uranium endowment is made before consideration of economic availabilityof any associated uranium 

resources. 

Uranium hexaflouride (UF6): Awhite solid obtained by chem ical treatment of U308and which forms a vapor at 

temperatures above 56 degrees Centigrade. UF6 is the form of uranium required for the enrichment process. 

Uranium importation: The actual physical movement of uranium from a location outside the United States to a location 

inside the United States. 

Uranium mill: A plant where uranium is separated from ore taken from mines. 

Uranium mill tailings: The sand-like materials left over from the separation of uranium from its ore. More than 99 percent of 

the ore becomes tailings. 

Uranium Mill Tailings Radiation Control A (UMTRA) of 1978: The act that directed the Department of Energy to provide for 

stabilization and control of the uranium mill tailings from in active sites in a safe and environmentally sound manner to 

minimize radiation health hazards to the public. It authorized the Department to undertake remedial actions at 24 

designated inactive uranium-processing sites and at an estimated 5,048 vicinity properties. 

Uranium ore: Rock containing uranium mineralization in concentrations that can be mined economically, typically one to 

four pounds of U308 per ton or 0.05 percent to 0.2 percent U308. 

Uranium oxide: Uranium concentrate or yellowcake. Abbreviated as U308. 

Uranium property: Aspecific piece of land with uranium reserves that is held for the ultimate purpose of economically 

recovering the uranium. The land can be developed for production or undeveloped. 

Uranium reserves: Estimated quantities of uranium in known mineral deposits of such size, grade, and configuration that 

the uranium could be recovered at or below a specified production cost with currently proven mining and processing 

technology and under current law and regulations. Reserves are based on direct radiometric and chemical measurements 

of drill holes and other types of sampling of the deposits. Mineral grades and thickness, spatial relationships, depths below 

the surface, mining and reclamation methods, distances to milling facilities, and amenability of ores to processing are 

considered in the evaluation. The amount of uranium in ore that could be exploited within the chosen forward-cost levels are 

estimated in accordance with conventional engineering practices. 

Uranium resource categories (international): Three categories of uranium resources defined bythe international 

communityto reflect differing levels of confidence in the existence of the resources. Reasonably assured resources (RAR), 

estimated additional resources (EAR), and speculative resources (SR) are described below. 

• Reasonably assured resources (RAR): Uranium that occurs in known mineral deposits of such size, grade, and 

configuration that it could be recovered within the given production cost ranges, with currently proven mining and 

processing technology. Estimates of tonnage and grade are based on specific sample data and measurements of 

the deposits and on knowledge of deposit characteristics. Note: RAR corresponds to DOE's uranium reserves 

category. 

• Estimated additional resources (EAR): Uranium in addition to RAR that is expected to occur, mostly on the basis of 

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geological evidence, in extensions of well-explored deposits, in little-explored deposits, and in undiscovered 

deposits believed to exist along well-defined geological trends with known deposits. This uranium can subsequently 

be recovered within the given cost ranges. Estimates of tonnage and grade are based on available sampling data 

and on knowledge of the deposit characteristics, as determined in the best-known parts of the deposit or in similar 

deposits. Note: EAR corresponds to DOE's probable potential resources category. 

• Speculative resources (SR): Uranium in addition to EARthat is thought to exist, mostly on the basis of indirect 

evidence and geological extrapolations, in deposits discoverable with existing exploration techniques. The location 

of deposits in this category can generally be specified only as being somewhere within given regions or geological 

trends. The estimates in this category are less reliable than estimates of RAR and EAR. Note: SR corresponds to the 

combination of DOE's possible potential resources and speculative potential resources categories. 

USACE (sometimes shortened to USCE in 8A tables): U.S. Army Corps of Engineers. 

USSR: United States Bureau of Reclamation. 

Useage agreement: Contracts held by enrichment customers that allow feed material to be stored at the enrichment plant 

site in advance of need. 

Used and useful: Aconcept used by regulators to determine whether an asset should be included in the utility's rate base. 

This concept requires that an asset currently provide or be capable of providing a needed service to customers. 

Useful thermal output: The thermal energy made available in a combined-heat-and-power system for use in any industrial 

or commercial process, heating or cooling application, or delivered to other end users, i.e., total thermal energy made 

available for processes and applications other than electrical generation. 

Utility: SeeElectric utility. 

Utility demand-side management costs: The costs incurred bythe utility to achieve the capacity and energy savings from 

theDemand-Side Management(DSM) Program. Costs incurred by consumers or third parties are to be excluded. The costs 

are to be reported in nominal dollars in the year in which they are incurred, regardless of when the savings occur. The utility 

costs are all the annual expenses (labor, administrative, equipment, incentives, marketing, monitoring and evaluation, and 

other) incurred by the utility for operation of the DSM Program, regardless of whether the costs are expensed or capitalized. 

Lump-sum capital costs (typically accrued over several years prior to start up) are not to be reported. Program costs 

associated with strategic load growth activities are also to be excluded. 

Utility distribution companies: The entities that will continue to provide regulated services for the distribution of electricity to 

customers and serve customers who do not choose direct access. Regardless of where a consumer chooses to purchase 

power, the customer's current utility, also known as the utility distribution company, will deliver the power to the consumer. 

Utility generation: Generation by electric systems engaged in selling electric energyto the public. 

Utility-sponsored conservation program: Any program sponsored by an electric and/or natural gas utility to review 

equipment and construction features in buildings and advise on ways to increase the energyefficiencyof buildings. Also 

included are utility-sponsored programs to encourage the use of more energy-efficient equipment. Included are programs 

to improve the energyefficiency in the lighting system or building equipment or the thermal efficiencyof the building shell. 

Also seeDemand-side management. 

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V 

V: SeeVolt 

Vacuum distillation: Distillation under reduced pressure (less the atmospheric) which lowers the boiling temperature of 

the liquid being distilled. This technique with its relatively low temperatures prevents cracking or decomposition of the 

charge stock. 

Value (of shipments): The value received for the complete systems at the corn panys net billing price, freight-on-board 

factory, including charges for cooperative advertising and warranties. This does not include excise taxes, freight or 

transportation charges, or installation charges. 

Value added by manufacture: A measure of manufacturing activity that is derived by subtracting the cost of materials 

(which covers materials, supplies, containers, fuel, purchased electricity, and contract work) f the value of shipments. 

This difference is then adjusted bythe net change in finished goods and work-in-progress between the beginning- and 

end-of-year inventories. 

Vapor displacement: The release of vapors that had previously occupied space above liquid fuels stored in tanks. These 

releases occur when tanks are emptied and filled. 

Vapor retarder: A material that retards the movement of water vapor through a building element (walls, ceilings) and 

prevents insulation and structural wood from becoming damp and metals from corroding. Often applied to insulation baits 

or separately in the form of treated papers, plastic sheets, and metallic foils. 

Vapor-dominated geothermal system: A conceptual model of a hydrothermal system where steam pervades the rock and 

is the pressure-controlling fluid phase. 

Variable air volume (VAV) system on the heating and cooling system: A means of varying the amount of conditioned air to 

a space. Avariable air volume system maintains the airflow at a constant temperature, but supplies varying quantities of 

conditioned air in different parts of the building according to the heating and cooling needs. 

Variable fuel vehicle: SeeFlexible fuel vehicle. 

Variable-speed wind turbines: Turbines in which the rotor speed increases and decreases with changing wind speed, 

producing electricitywith a variable frequency. 

VAWT: SeeVertical-Ms Wind Turbine 

Vehicle fuel consumption: Vehicle fuel consumption is computed as the vehicle miles traveled divided bythe fuel efficiency 

reported in miles per gallon (MPG). Vehicle fuel consumption is derived from the actual vehicle mileage collected and the 

assigned MPGs obtained from EPA certification files adjusted for on-road driving. The quantity off I used byvehicles. 

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Vehicle fuel efficiencies: See Miles per gallon. 

Vehicle fuel expenditures: The cost, including taxes, of the gasoline, gasohol, or diesel f I added to the vehicle's tank. 

Expenditures do not include the cost of oil or other items that may have been purchased at the same time as the vehicle 

fuel. 

Vehicle identification number (VIN): Aset of codes, usually alphanumeric characters, assigned to a vehicle at the factory 

and inscribed on the vehicle. When decoded, the VIN provides vehicle characteristics. The VIN is used to help match 

vehicles to the EPA certification file for calculating MPGs. 

Vehicle importer: An original vehicle manufacturer (of foreign or domestic ownership) that imports vehicles as finished 

products into the United States. 

Vehicle miles traveled (VMT): The number of miles traveled nationally byvehicles for a period of 1 year. V T is either 

calculated using two odometer readings or, for vehicles with less than two odometer readings, imputed using a regression 

estimate. 

Vented: Natural gas that is disposed of by releasing to the atmosphere. 

Vented natural gas: See vented. 

Vented/Flared: Gas that is disposed of by releasing (venting) or burning (flaring). 

Ventilation system: A method for reducing methane concentrations in coal mines to non-explosive levels by blowing air 

across the mine face and using large exhaust fans to remove methane while mining operations proceed. 

Vertical integration: The combination within a firm or business enterprise of one or more stages of production or 

distribution. In the electric industry, it refers to the historical arrangement whereby a utility owns its own generating plants, 

transmission system, and distribution lines to provide all aspects of electric service. 

Vertical-axis wind turbine (VAWT): A type of wind turbine in which the axis of rotation is perpendicular to the windstream 

and the ground. 

Vessel: A ship used to transport crude oil, petroleum products, or natural gas products. Vessel categories are as follows: 

Ultra Large Crude Carrier (ULCC), Very Large Crude Carrier (VLCC), Other Tanker, and Specialt (LPG/LNG). See 

Tanker and Barge. 

Vessel bunkering: Includes sales for the fueling of commercial or private boats, such as pleasure craft, f 

tugboats, and ocean-going vessels, including vessels operated by oil companies. Excluded are volumes sold to the U.S. 

Armed Forces. 

VIN: See Vehicle Identification Number 

VIN (vehicle identification number): Aset of about 17 codes, combining letters and numbers, assigned to a vehicle at the 

factory and inscribed on a small metal label attached to the dashboard and visible through the windshield. The VIN is a 

unique identifier for the vehicle and therefore is often found on insurance cards, vehicle registrations, vehicle titles, safety or 

emission certificates, insurance policies, and bills of sale. The coded information in the VIN describes characteristics of the 

vehicle such as engine size and weight. 

Virgin coal: Coal that has not been accessed by mining. 

Visbreaking: Athermal cracking process in which heavy atmospheric or vacuum-still bottoms are cracked at moderate 

temperatures to increase production of distillate products and reduce viscosity of the distillation residues. 

VLCC: Very Large Crude Carrier 

VMT: See Vehicle Miles Traveled 

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VOC: SeeVolatile Organic Compound 

Volatile matter: Those products, exclusive of moisture, given off by a material as gas or vapor. Volatile matter is 

determined by heating the coal to 950 degrees Centigrade under carefully controlled conditions and measuring the weight 

loss, excluding weight of moisture driven off at 105 degrees Centigrade. 

Volatile organic compounds (VOCs): Organic compounds that participate in atmospheric photochemical reactions. 

Volatile solids: A solid material that is readily decomposable at relatively low temperatures. 

Volt (V): The volt is the International System of Units(SI) measure of electric potential or electromotive force. A potential of 

one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance. Reduced to 

SI base units, 1 V= 1kg times m2 times S

-3 times Kl

(kilogram meter squared per second cubed per ampere). 

Voltage: The difference in electrical potential between anytwo conductors or between a conductor and ground. It is a 

measure of the electric energy per electron that electrons can acquire and/or give up as they move between the two 

conductors. 

Voltage reduction: Any intentional reduction of system voltage by 3 percent or greater for reasons of maintaining the 

continuity of service of the bulk electric power supplysystem. 

Volumetric wires charge: SeeQuantity wires charge. 

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W: SeeWatt 

WACOG: Weighted Average Cost of Gas 

Wafer: A thin sheet of semiconductor (photovoltaic material) made by cutting it from a single crystal or ingot. 

Walk-in refrigeration units: Refrigeration/freezer units within a building that are large enough to walk into. They may be 

portable or permanent, such as a meat storage locker in a butcher store. Walk-in units mayor may not have a door, plastic 

strips, or other flexible covers. 

Wall insulation: Insulating materials within or on the walls between heated areas of the building and unheated areas or the 

outside. The walls may separate air-conditioned areas from areas not air-conditioned. 

Warm-air furnace: SeeFurnace. 

Warranty contracts: Gas purchase agreements for the sale of natural gas by a producer to a pipeline company wherein 

the producer warrants it will have available sufficient gas supplies to meet its commitments over the life of the contract. 

Generally, the producer does not dedicate gas reserves underly fic acreage, lease, or fields to the agreement. 

Substitution of various sources of gas supply may be permitted according to the terms of the contract. Warranty contracts, by 

their terms, mayvaryfrom the above. 

Waste: SeeBiomass wasteand Non-biomass waste. 

Waste coal: Usable material that is a byproduct of previous coal processing operations. Waste coal is usually composed 

of mixed coal, soil, and rock (mine waste). Most waste coal is burned as-is in unconventional fluidized-bed combustors. For 

some uses, waste coal may be partially cleaned by removing some extraneous noncombustible constituents. Examples of 

waste coal include fine coal, coal obtained from a refuse bank or slurry dam, anthracite culm, bituminous gob, and lignite 

waste. 

Waste energy: Municipal solid waste, landfill gas, methane, digester gas, liquid acetonitrile waste, tall oil, waste alcohol, 

medical waste, paper pellets, sludge waste, solid byproducts, tires, agricultural byproducts, closed loop biomass, fish oil, 

and straw used as fuel. 

Waste heat boiler: A boiler that receives all or a substantial portion of its energy input from the combustible exhaust gases 

from a separate fuel-burning process. 

Waste heat recovery: Any conservation system whereby some space heating or water heating is done by actively capturing 

byproduct heat that would otherwise be ejected into the environment. In commercial buildings, sources of water- heat 

recovery include refrigeration/air-conditioner compressors, manufacturing or other processes, data processing centers, 

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lighting fixtures, ventilation exhaust air, and the occupants themselves. Not to be considered is the passive use of radiant 

heat from lighting, workers, motors, ovens, etc., when there are no special systems for collecting and redistributing heat. 

Waste materials: Otherwise discarded combustible materials that, when burned, produce energyfor such purposes as 

space heating and electric power generation. The size of the waste may be reduced by s hredders, grinders, or 

hamm erm ills. Noncombustible materials, if any, may be removed. The waste may be dried and then burned, either alone or 

in combination with fossil f Is. 

Waste oils and tar: Petroleum-based materials that are worthless for any purpose other than fuel use. 

Wastewater, domestic and commercial: Wastewater (sewage) produced by domestic and commercial establishments. 

Wastewater, industrial: Wastewater produced by industrial processes. 

Water bed heater: An appliance that uses an electric resistance coil to maintain the temperature of the water in a water 

bed at a comfortable level. 

Water conditions: The status of the water supply and associated water in pondage and reservoirs at hydroelectric plants. 

Water heated in furnace: Some furnaces provide hot water as well as heat the home. The water is heated by a coil that is 

part of the furnace. There is no separate hot water tank. 

Water heater: An automatically controlled, thermally insulated vessel designed for heating water and storing heated water 

at temperatures less than 180 degrees Fahrenheit. 

Water heating DSM programs: These are demand-side management (DSM) programs designed to promote increased 

efficiency in water heating, including water heater insulation wraps. 

Water heating equipment: Automatically controlled, thermal insulated equipment designed for heating and storing heated 

water at temperatures less than 180 degrees Fahrenheit for other than space heating purposes. 

Water pollution abatement equipment: Equipment used to reduce or eliminate water borne pollutants, including chlorine, 

phosphates, acids, bases, hydrocarbons, sewage, and other pollutants. Examples of water pollution abatement structures 

and equipment include those used to treat thermal pollution; cooling, boiler, and cooling tower blowdown water; coal pile 

runoff; and fly ash waste water. Water pollution abatement excludes expenditures for treatment of water prior to use at the 

plant. 

Water pumping: Photovoltaic modules/cells used for pumping water for agricultural, land reclamation, commercial, and 

other similar applications where water pumping is the main use. 

Water reservoir: A large inland body of water collected and stored above ground in a natural or artificial formation. 

Water source heat pump: A type of (geothermal) heat pump that uses well (ground) or surface water as a heat source. 

Water has a more stable seasonal temperature than air thus making for a more efficient heat source. 

Water turbine: Aturbine that uses water pressure to rotate its blades; the prim ary types are the Pelton wheel, for high 

heads (pressure); the Francis turbine, for low to medium heads; and the Kaplan for a wide range of heads. Primarily used 

to power an electric generator. 

Water vapor: Water in a vaporous form, especiallywhen below boiling temperature and diffused (e.g., in the atmosphere). 

Water well: Awell drilled to (1) obtain a water supplyto support drilling or plant operations, or (2) obtain a water supplyto 

be used in connection with an improved recovery program. 

Water wheel: A wheel that is designed to use the weight and/or force of moving water to turn it, primarily to operate 

machinery or grind grain. 

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Waterway: A river, channel, canal, or other navigable body of water used for travel or transport. 

Watt (W): The unit of electrical power equal to one ampere under a pressure of one volt. A Watt is equal to 1/746 horse 

power. 

Watthour (Wh): The electrical energy unit of measure equal to one watt of power supplied to, or taken from, an electric 

circuit steadilyfor one hour. 

Wattmeter: A device for measuring power consumption. 

Wax: Asolid or semi-solid material consisting of a mixture of hydrocarbons obtained or derived from petroleum fractions, 

or through a Fischer-Tropsch type process, in which the straight- chained paraffin series predominates. This includes all 

marketable wax, whether crude or refined, with a congealing point (ASTM D 938) between 100 and 200 degrees Fahrenheit 

and a maximum oil content (ASTM D 3235) of 50 weight percent. 

Weather stripping or caulking: Any of several kinds of crack-filling material around anywindows or doors to the outside 

used to reduce the passage of air and moisture around moveable parts of a door or window. Weather stripping is available 

in strips or rolls of metal, vinyl, or foam rubber and can be applied on the inside or outside of a building. 

Weir: Adam in a waterway over which water flows and that serves to raise the water level or to direct or regulate flow. 

Well: A hole drilled in the earth for the purpose of: 

1. finding or producing crude oil or natural gas; or 

2. producing services related to the production of crude or natural gas. 

Well water for cooling: A m eans of cooling that uses water from a well drilled specificallyfor that purpose. The 

subterranean temperature of the water stays at a relatively constant temperature. Where water is abundant, it provides a 

means of getting 55-degree Fahrenheit water with no mechanical cooling. Used usuallyfor heat rejection in a water source 

heat pump. 

Wellhead: The point at which the crude (and/or natural gas) exits the ground. Following historical precedent, the volume 

and price for crude oil production are labeled as "wellhead, "even though the cost and volume are now generally measured 

at the lease boundary. In the context of domestic crude price data, the term "wellhead" is the generic term used to reference 

the production site or lease property. 

Wellhead price: The value at the mouth of the well. In general, the wellhead price is considered to be the sales price 

obtainable from a third party in an arm's length transaction. Posted prices, requested prices, or prices as defined by lease 

agreements, contracts, or tax regulations should be used where applicable. 

West Texas Intermediate (WTI - Cushing): A crude stream produced in Texas and southern Oklahoma which serves as a 

reference or "marker" for pricing a number of other crude streams and which is traded in the domestic spot market at 

Cushing, Oklahoma. 

Wet bottom boiler: Slag tanks are installed usually at the furnace throat to contain and remove molten ash. 

Wet natural gas: A mixture of hydrocarbon compounds and small quantities of various non hydrocarbons existing in the 

gaseous phase or in solution with crude oil in porous rock formations at reservoir conditions. The principal hydrocarbons 

normally contained in the mixture are methane, ethane, propane, butane, and pentane. T I nonhydrocarbon gases that 

may be present in reservoir natural gas are water vapor, carbon dioxide, hydrogen sulf 

lium. Under reservoir conditions, natural gas and its associated liquefiable portions occur either in a single gaseous 

phase in the reservoir or in solution with crude oil and are not distinguishable at the time as separate substances. Note: 

The Securities and Exchange Commission and the Financial Accounting Standards Board refer to this product as natural 

gas. 

Wh: See Watthour 

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Wheeling charge: An amount charged by one electrical system to transmit the energy of, and for, another system or 

systems. 

Wheeling service: The movement of electricity from one system to another over transmission facilities of interconnecting 

systems. Wheeling service contracts can be established between two or more systems. 

White spirit: A highly refined distillate with a boiling point range of about 150 degrees to 200 degrees Centigrade. It is used 

as a paint solvent and for dry-cleaning purposes. 

Whole-house cooling fan: A nnechanical/electrical device used to pull air out of an interior space; usually located in the 

highest location of a building, in the ceiling, and venting to the attic or directly to the outside. 

Wholesale competition: Asystem whereby a distributor of power would have the option to buy its power from a variety of 

power producers, and the power producers would be able to compete to sell their power to a variety of distribution 

corn panies. 

Wholesale electric power market: The purchase and sale of electricity from generators to resellers (retailers), along with 

the ancillaryservices needed to maintain reliabilityand power qualityat the transmission level. 

Wholesale power market: The purchase and sale of electricityfrom generators to resellers (who sell to retail customers), 

along with the ancillaryservices needed to maintain reliabilityand power qualityat the transmission level. 

Wholesale price: The rack sales price charged for No. 2 heating oil; that is, the price charged customers who purchase 

No. 2 heating oil free-on-board at a supplier's terminal and provide their own transportation for the product. 

Wholesale sales: Energysupplied to other electric utilities, cooperatives, municipals, and Federal and state electric 

agencies for resale to ultimate consumers. 

Wholesale transmission services: The transmission of electric energy sold, or to be sold, in the wholesale electric power 

market. 

Wholesale wheeling: An arrangement in which electricity is transmitted from a generator to a utility through the 

transmission facilities of an intervening system. 

Wi: Withheld to avoid disclosure of individual company data. 

Wind energy: Kinetic energy present in wind motion that can be converted to mechanical energy for driving pumps, mills, 

and electric power generators. 

Wind energy conversion system (WECS) or device: An apparatus for converting the energy available in the wind to 

mechanical energy that can be used to power machinery (grain mills, water pumps) and to operate an electrical generator. 

Wind farm: SeeWind power plant. 

Wind power plant: Agroup of wind turbines interconnected to a common utility system through a system of transformers, 

distribution lines, and (usually) one substation. Operation, control, and maintenance functions are often centralized through 

a network of computerized monitoring systems, supplemented byvisual inspection. This is a term commonly used in the 

United States. In Europe, it is called a generating station. 

Wind turbine: Wind energy conversion device that produces electricity, typically three blades rotating about a horizontal aids 

and positioned up-wind of the supporting tower. 

Wires charge: Abroad term referring to fees levied on power suppliers or their customers for the use of the transmission 

or distribution wires. 

Withdrawals: The volume of natural gas removed from storage reservoirs. 

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Wood conversion to Btu: Converting cords of wood into a Btu equivalent is an imprecise procedure. The number of cords 

each household reports having burned is in exact, even with the more precise drawings provided, because the estimate 

requires the respondent to add up the use of wood over a 12-month period during which wood may have been added to the 

supply as well as removed. Besides errors of memory inherent in this task, the estimates are subject to problems in 

definition and perception of what a cord is. The nominal cord as delivered to a suburban residential buyer may differ from 

the dimensions of the standard cord. This difference is possible because wood is most often cut in lengths that are longer 

than what makes a third of a cord(16 inches) and shorter than what makes a half cord (24 inches). 

In other cases, wood is bought or cut in unusual units (for example, pickup-truck load, or trunk load). Finally, volume 

estimates are difficult to make when the wood is left in a pile instead of being stacked. Other factors that make it difficult to 

estimate the Btu value of the wood burned is that the amount of empty space between the stacked logs mayvaryfrom 12 to 

40 percent of the volume. Moisture content mayvaryfrom 20 percent in dried wood to 50 percent in green wood. (Moisture 

reduces the useful Btu output because energy is used in driving off the moisture). Finally, some tree species contain twice 

the Btu content of species with the lowest Btu value. Generally lue than softwoods. Wood is 

converted to Btu at the rate of 20 million Btu per cord, which is a rough average that takes all these factors into account. Also 

see Btu conversion factors. 

Wood energy: Wood and wood products used as fuel, including round wood (cord wood), limb wood, wood chips, bark, 

saw dust, forest residues, charcoal, pulp waste, and spent pulping liquor. 

Wood pellets: Saw dust compressed into uniform diameter pellets to be burned in a heating stove. 

Working (top storage) gas: The volume of gas in the reservoir that is in addition to the cushion or base gas. It mayor may 

not be corn pletelywithdrawn during any particular withdrawal season. Conditions permitting, the total working capacity 

could be used more than once during any season. 

Working interest: An interest in a mineral property that entitles the owner of that interest to all of share of the mineral 

production from the property, usually subject to a royalt . Aworking interest permits the owner to explore, develop, and 

operate the property. The working-interest owner bears the costs of exploration, development, and operation of the property 

and, in return, is entitled to a share of the mineral production from the property or to a share of the proceeds there from. It 

may be assigned to another party in whole or in part, or it may be divided into other special property interests. 

• Gross working interest. The reporting company's working interest plus the proportionate share of any basic royalty 

interest or overriding royalt lated to the working interest. 

• Networking interest. The reporting companys working interest is not including any basic royalt It 

Working storage capacity: The difference in volume between the maximum safe fill capacity and the quantity below which 

pump suction is ineffective (bottoms). 

WTI: West Texas Intermediate 

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Xylene (C6H4(CH3)2): Colorless liquid of the aromatic group of hydrocarbons made the catalytic reforming of certain 

naphthenic petroleum fractions. Used as high-octane motor and aviation gasoline blending agents, solvents, chemical 

intermediates. Isomers are metmglene, orthoxylene, paraxylene. 

Yellowcake: A natural uranium concentrate that takes its name from its color and texture. Yellowcake typically contains 70 

to 90 percent U308 (uranium oxide) by weight. It is used as feedstock for uranium fuel enrichment and fuel pellet 

fabrication. 

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