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E85: A fuel containing a mixture of 85 percent ethanol and 15 percent gasoline. See Motor gasoline (finished).

E95: A fuel 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 Energy that 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 at http://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: See Gross 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 

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power producers) and industrial and commercial power generators, including combined-heat-and-power producers, but 

excludes units at single-family dwellings.

Electric generator: A facility that produces only electricity, commonly 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 employ 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 from rechargeable storage 

batteries, fuel cells, photovoltaic arrays, or other sources of electric current.

Electric non-utility: Any entity that generates, transmits, or sells electricity, or sells or trades electricity services 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: A system of synchronized power providers and consumers connected by transmission 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 auxiliary equipment for converting 

mechanical, chemical, and/or fission energy into electric energy.

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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 Industry 

Classification System 22 plants. See also Combined heat and power (CHP) plant and 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 

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 statement 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 encompasses 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 implies 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 energy for use primarily by the public. Included are investor-owned electric utilities, municipal 

and State utilities, Federal electric utilities, and rural electric cooperatives. A few 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 company's 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 any one 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 by the independent system operator.

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Electrical system energy losses: The amount of energy lost during generation, transmission, and distribution of electricity, 

including plant and unaccounted for use.

Electricity: A form of energy characterized by the 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 

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 (MWh).

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 by the 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 important 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).

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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 by water 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 

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 Energy Assistance Program.

Energy audit: A program carried out by a utility company in which an auditor inspects a home and suggests ways energy 

can be saved.

Energy broker system: Introduced into Florida by the 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 by the 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: Energy generated by on electric utility system 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.

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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 consumption 

(reported in megawatthours), often without explicit consideration for the timing of program-induced savings. Such savings are 

generally achieved by substituting 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.

Energy exchange: Any transaction in which quantities of energy are received or given up in return for similar energy 

products. See exchange, electricity; exchange, petroleum; 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 agency within the U.S. Department of Energy that develops 

surveys, collects energy data, and does analytical and modeling analyses of energy issues. The Agency must satisfy 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.

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 energy for 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.

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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 specific end-use systems. This includes the following EMCS, DSM Program 

Participation, Energy Audit, 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.

Energy sale(s): The transfer of title to an energy commodity 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 efficiency 

programs and 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 supplying electricity, 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 fuel 

consumed. If the level of fuel 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 Classification(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.

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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 ultimately will 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 (by weight) 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 

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 quality, air quality 

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 EPA standards for clean burning.

EPA composite MPG: The harmonic mean of the EPA city 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.

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Equity (financial): Ownership of shareholders in a corporation represented by stock.

Equity capital: The sum of capital from retained earnings and the issuance of stock.

Equity crude oil: The proportion of production that a concession owner has the legal and contractual right to retain.

Equity in earnings of unconsolidated affiliates: A company's 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): A clear, colorless, flammable alcohol. Ethanol is typically produced biologically from biomass feedstocks 

such as agricultural crops and cellulosic residues from agricultural crops or wood. Ethanol can also be produced chemically 

from ethylene. See Biomass, 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 the Union 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.

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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: See energy 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 company to another company, in exchange for the 

delivery by the second company to 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. See energy exchange.

Exchange energy: See exchange, electricity.

Exchange, electricity: A type 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 as exchange energy.

Exchange, natural gas: A type 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 

may or may not include the payment of fees in dollar or volumetric amounts.

Exchange, petroleum: A type 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.

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 Company Act 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 fuel.

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.

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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) further exploring 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 significantly distort the current year's net income if 

reported other than as extraordinary items.

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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

N

N2O: 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: See Generator 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: See Petrochemical feedstocks.

Naphtha-type jet fuel: A fuel 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 primarily for military turbojet 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-type jet fuel is included in Miscellaneous 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: See National 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.

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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 Agency's list of the most serious uncontrolled or abandoned 

hazardous waste sites identified for possible long-term remedial action under the Comprehensive Environmental 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 they serve. 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: A gaseous mixture of hydrocarbon compounds, the primary one being methane.

Natural gas field facility: A field 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. They form 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, 

natural 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, field 

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.

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Natural gas marketer: A company that 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 supply of natural gas, such as 

pipelines or storage fields. A marketer may be an affiliate of another company, such as a local distribution company, natural 

gas pipeline, or producer, but it operates independently of 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 

plants, fractionating and cycling 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 may be 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 may or 

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: See Dry natural gas production.

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": See Dry natural gas.

Natural gasoline: A term used in the gas processing industry to 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 by fractionation 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 may be the result of 

"dissolved gas drive," "gas cap drive," or "water drive." Regardless of the type of drive, 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 energy futures 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: See North American Electric Reliability Corporation.

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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 computed as generation, plus imports, minus exports, minus 

transmission and distribution losses.

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 Authority Areas through interchange. It includes Balancing Authority Area 

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 electricity for 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 (MW), that generating equipment can 

supply to system load, as demonstrated by a 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.

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Net winter capacity: The maximum output, commonly expressed in megawatts (MW), that generating equipment can 

supply to system load, as demonstrated by a 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 by sales 

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 importation.

New field: A field 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 

new fields during the report year.

New reservoir: A reservoir discovered during the report year.

NGL: See Natural gas liquids.

NGPA: See Natural Gas Policy Act of 1978. 

NGPL: Natural Gas Plant Liquids

NGV: Natural Gas Vehicle

Nitrogen dioxide: A compound 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 by the burning of fossil fuels.

Nitrous oxide (N2O): A colorless gas, naturally occurring in the atmosphere. Nitrous oxide has a 100-year Global Warming 

Potential of 310.

No. 1 diesel fuel: A light distillate fuel oil that has a distillation temperature 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: 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).

No. 1 fuel oil: A light 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).

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No. 2 fuel oil (heating oil): 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 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 fuel 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 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. 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: See Nitrogen oxides

NOAA: National Oceanic and Atmospheric Administration.

NOAA division: One of the 345 weather divisions designated by the National Oceanic and Atmospheric Administration 

(NOAA) 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 measure 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 quality standard 

established by the Environmental Protection Agency for designated pollutants, such as carbon monoxide and ozone.

Nonbranded product: Any refined petroleum product that is not a branded product.

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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): A facility engineered and built principally for 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.

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 by water 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., royalty, 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: A wholesale 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 AFVs (golf carts, snow mobiles, pleasure watercraft, etc.) are excluded from the definition.

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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 (C4H10): 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 Reliability Council established to develop and maintain mandatory reliability standards 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 the North American Electric Reliability Corporation (NERC) Regions.

North American Industry Classification System (NAICS): A new classification scheme, developed by the Office of 

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: See National 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.

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NURE: See National Uranium Resource Evaluation

NYMEX: New York Mercantile Exchange

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