Appendix B

Survey Design,

Implementation,

and Estimates

Appendix B

Survey Design, Implementation, and Estimates

Introduction

The 1991 Manufacturing Energy Consumption Survey (MECS) has been designed by the Energy Information

Administration (EIA) to provide information related to energy consumption in the manufacturing sector of the U.S

economy. It is the third such survey to be completed. The MECS is an ongoing survey that is conducted every 3

years. Beginning in 1994, the MECS will be conducted every 2 years to determine the trends in manufacturing

energy use more accurately.

The basic unit of data collection for this survey is the manufacturing establishment. A nationally representative

sample of these establishments supplied the information through mailed questionnaires. The Industry Division of

the Bureau of the Census, in consultation with EIA, selected the MECS sample, conducted fieldwork, and processed

the data.

This appendix presents a summary of the design and Overview of Changes

from the 1988 Survey

Sample Design. The designed sample size was increased

from approximately 12,000 establishments to 16,000.

Sample cases were not automatically retained from the

previous survey cycle; the sample was selected directly

from the 1991 Annual Survey of Manufactures (ASM) file.

Coverage. New frame updating procedures instituted by

the Bureau of the Census allowed for consistent coverage

of the manufacturing sector mail surveys. For that reason,

the coverage in the 1991 MECS is 98 percent of the

manufacturing population as measured in total payroll.

The sampling process itself provided that level of

coverage, and no special adjustments were used to increase

it. The 1988 survey covered 100 percent of the population

but special adjustments to the survey estimates were

required to achieve complete coverage. Therefore, many

of the potential sources of bias that pertained to the 1988

survey estimates are not relevant to the 1991 survey.

Because of the difference in coverage between the two

years, care must be exercised when comparing absolute

quantities. Small differences might be correctly

attributable to coverage rather than real change.

Industry Estimates. The increase in sample size allowed

for separate estimates for 42 industries and industry groups

in addition to the 20 larger major groups. In 1988, there

were only 10 industries for which separate estimates were

publishable beyond the 20 major groups.

(Continued on Next Page)

implementation procedures for the survey, highlights

differences between reporting periods, and describes

the types of estimates included in this report. For

more detailed design, methodology, and background

information refer to the EIA publication

Manufacturing Energy Consumption Survey:

Methodological Report, DOE/EIA-0514

(Washington, DC, 1988).

Description of the

Manufacturing Sector

The manufacturing sector consists of all

manufacturing establishments in the 50 States and

the District of Columbia. The working definition of

a manufacturing establishment is the definition

stated in the Office of Management and Budget’s

Standard Industrial Classification (SIC) Manual:

[Manufacturing establishments are] ...

engaged in the mechanical or chemical

transformation of materials or substances

into new products. These establishments

are usually described as plants, factories,

or mills and characteristically use power

driven machines and materials handling

equipment. Establishments engaged in

assembling component parts of

manufactured products are also considered

manufacturing if the new product is neither

a structure nor other fixed improvement.

Also included is the blending of materials

such as lubricating oil, plastics, resins, or

liquors.20

20Office of Management and Budget, Standard Industrial Classification Manual, 1987 (Washington, DC, 1987), p. 67.

Energy Information Administration/Manufacturing Consumption of Energy 1991 437
The SIC Manual contains a hierarchial classification Additional Data Items for Improved Estimation. EIA

has recognized a potential for overestimating energy source

quantities in industries that produce and sell energy

sources. This will occur when an establishment in such an

industry uses an energy source as an input to a process

(i.e, feedstock), produces another energy source as a result

of that process, and then sells or transfers the produced

energy source to another establishment. The quantity of

the receipt in the second establishment would duplicate the

feedstock use in the first. Part of the solution has been to

estimate consumption in petroleum refineries differently

from other industries (see section entitled "Feedstocks and

Offsite-Produced Fuel at Petroleum Refineries" in this

appendix). To correct the problem for other industries, the

MECS now collects shipments offsite of energy sources

produced onsite (see "Development of the Data File" in

this appendix).

A second problem arose in estimating consumption

specifically for liquefied petroleum gases (LPG) and

petroleum coke. There are different types of those energy

sources and one type may be used in the production of

another. The collection of just the broad categories

hindered the proper identification and estimation of the

internal consumption-production flow. To address this

problem, the MECS now collects three categories of

petroleum coke and four categories of LPG.

New Data Collection Sections. The survey forms were

expanded to include sections on end-use energy

consumption, estimated square footage of building

floorspace, energy management activities (including

utility/supplier demand-side management), and energysaving technologies.

Discontinued Data Items. Two data items concerning

onsite electricity generation were discontinued. These

were interconnection status with an electric utility and

whether the establishment was a Qualifying Facility under

the Public Utility Regulatory Policies Act of 1978. These

items were no longer required because they are collected

as part of a new survey, Form EIA-867, "Annual

Nonutility Power Producer Report." Within the fuelswitching section, the data items concerning time required

to make a switch were discontinued. The MECS estimates

of fuel-switching capability are limited to a 30-day window

for eligibility. The additional respondent burden necessary

to further categorize this time was not justified by user

interest.

system that groups establishments according to their

primary economic activities. This system divides

the manufacturing sector (referred to as

"manufacturing division" in the SIC Manual) into 20

major industrial groups that are relatively

homogeneous with respect to primary output. Each

of these major industrial groups is assigned a

two-digit code. The two-digit codes for the

manufacturing sector range from SIC 20, Food and

Kindred Products, through SIC 39, Miscellaneous

Manufacturing Industries. Each major group is

subdivided into three-digit groups, which are further

divided into four-digit industries. For example, SIC

20 includes SIC 201, Meat Products, which, in turn,

is subdivided into SIC 2011, Meat Packing Plants;

SIC 2012, Sausages and Other Prepared Meat

Products; SIC 2016, Poultry Dressing Plants; and

SIC 2017, Poultry and Egg Processing.

The SIC category is the single most important

classification variable in the MECS data system,

both for selecting the MECS sample and analyzing

the MECS data. The categories of primary interest

for the MECS are the 20 major industrial groups

(SIC 20 through 39) and the 42 three- and four-digit

industries that consumed the most energy,

demonstrated high growth, or had a special

programmatic interest. A description of these 20

major industrial groups and 42 industry groups and

industries appears in Appendix G of this report.

The 1988 and 1991 MECS used the SIC

classification system presented in the 1987 edition

of SIC manual. The 1985 MECS was based on the

1972 SIC Manual. For the most part, the revisions

were minor and had a negligible effect on the

MECS estimates. However, there were some

revisions that would affect comparisons between

1985 and subsequent years. Among the more

significant revisions was the one concerning the

way certain petrochemical plants were classified for

the 1988 and 1991 MECS, as opposed to the 1985

MECS. If the primary product of a petrochemical

plant in 1985 was an LPG, it was classified in SIC

2911, Petroleum Refining, regardless of how the

LPG was produced. For the later survey years, the

establishment was classified in SIC 2911 only if the

LPG was produced by a refinery process. If the

LPG was produced by a chemical process, the

establishment was classified in organic chemicals

(SIC 2865 or 2869). Thus, when comparing the estimates for SIC’s 2911, 2865, and 2869 between 1985 and later

MECS reports, the reader is cautioned to take the classification differences into account.21

21An effort was made to account for the SIC revisions by reclassifying the 1988 MECS estimates according to the 1972 SIC codes. The

revised consumption estimates were used to form energy efficiency change estimates. See Energy Information Administration, Manufacturing

Energy Consumption Survey: Changes in Energy Intensity in the Manufacturing Sector, 1980-1988, DOE/EIA-0552(80-88) (Washington, DC,

1991). For future publications of this kind, the 1985 MECS estimates will be reclassified according to the 1987 SIC codes.

438 Energy Information Administration/Manufacturing Consumption of Energy 1991
The Sampling Frame and

Its Relationship to the Manufacturing Sector

As mentioned in the Introduction to this appendix, the Census Bureau serves as the collecting and compiling agent

for the MECS. A major responsibility of the Industry Division of the Census Bureau is to conduct the Census of

Manufactures (CM) and the Annual Survey of Manufactures (ASM).

Census of Manufactures

The CM is conducted for years ending in "2" or "7" (for example, 1987), and obtains economic data for the complete

universe of approximately 350,000 manufacturing establishments in the United States. For the purposes of data

collection, the CM universe is divided into two major subsets as follows.

1. Small Single-Establishment Companies Not Sent a Report Form. Generally, companies with less than

five employees are excused from filing a CM report. Those with 5 through 20 employees are excused or sent

a report form based on the magnitude of their annual payroll and shipments data. Approximately 125,000

establishments are excused due to this criterion.

2. Establishments Sent a Report Form. All companies with 20 or more employees are mailed a CM report

form.

Annual Survey of Manufactures

The ASM is conducted during non-CM years to provide estimates of economic characteristics for the universe of

manufacturing establishments. As with the CM, the ASM contains two components. The first component is the mail

portion, a probability sample of manufacturing establishments selected from the list of establishments that are sent

the CM report form (see above). Those establishments are weighted so that they represent the mail portion of the

CM universe. The second component of the ASM is the nonmail portion of the CM. These small establishments

are not sent an ASM questionnaire, but their contribution to economic statistics is estimated based on selected

information obtained annually from other Federal agencies.

The 1991 MECS sample was drawn directly from the 1987 CM with appropriate updates. That approach made the

coverage equivalent to the 1991 ASM mail file.22

Coverage Differences Between MECS 1985, 1988, and 1991

Due to differences among the 1985, 1988, and 1991 survey designs, the coverage of manufacturing establishments

varied slightly from survey to survey. Therefore, comparisons of estimates produced from the surveys and analysis

of trends must be done with caution.

The 1991 MECS covers 98 percent of the manufacturing sector as measured by total payroll. The two percent of

the payroll not covered is known to be represented by a population of relatively small but numerous manufacturing

establishments. When taken as a whole, they account for roughly two percent of a number of different economic

measures, including energy consumption. The cost and difficulty of accurately surveying this population necessitated

the decision to exclude it from the estimates presented in this report.

22Establishments that were first eligible for the MECS in calendar year 1991 were not mailed a questionnaire. Rather, their contribution was

accounted for in the nonresponse adjustment. See section entitled "Estimation Process" in this appendix.

Energy Information Administration/Manufacturing Consumption of Energy 1991 439
The 1988 MECS estimates covered the entire manufacturing sector. The small establishments excluded from the

1991 survey were "included" by means of a population adjustment factor. That adjustment factor was necessitated

because of normal degradation of the sample coupled with the desire to retain the active portion of the 1985 sample,

rather than entirely reselect the sample. This method meant that establishments had to be classified according to very

specific definitions. For example, establishments that ceased operation since 1985 had to be distinguished from those

that merely underwent a change of ownership. To counteract the operational errors that might have occurred while

maintaining a sample built in this way, a ratio adjustment to the 1987 CM was chosen. That adjustment by necessity

also included the portion of the manufacturing sector that was not originally intended for estimation, the two percent

of certain economic measures represented by the smallest establishments.23 The 1991 survey did not use an

adjustment factor because: (1) there was no readily available population adjustment for 1991 estimates, and (2) the

relative simplicity of the sample design yielded fewer operational errors.

The 1985 estimates excluded the smallest establishments from coverage. This would tend to make 1985 coverage

comparable with 1991. Due to Census updating procedures that were in place during the 1985 survey, the coverage

might have been somewhat less than the 98 percent of the 1991 survey, but exact estimates of coverage are difficult

to estimate. Therefore, caution must be exercised by readers who wish to compare 1985, 1988, and 1991

estimates.24

Sample Design

Sample Size

The designed size of the MECS sample was set at 16,000. Previous data have shown that this size sample optimally

allocated to the various strata would lead to estimates having desired sampling error. The targeted sampling errors

in terms of relative standard errors (RSE) for previous MECS samples were:

• No more than two percent for total energy consumption in energy-intensive SIC major groups or specific

industries;

• No more than five percent for total energy consumption in the other SIC groups; and

• No more than ten percent for the four major fuel categories (electricity, natural gas, coal, and the aggregate

of all remaining energy sources) in any SIC that contributes more than one percent of the total national

consumption of that fuel.

The 1991 MECS sample was designed using the experience of the 1985 and 1988 sample designs and estimated

sampling errors for those surveys. That experience and knowledge of the current ASM populations allowed the

sample sizes to be allocated so that the RSE targets could be met for 1991.25

23For a more detailed explanation of the population adjustment factor, see Appendix A, Energy Information Administration, Manufacturing

Energy Consumption Survey: Consumption of Energy, 1988, DOE/EIA-0512(88), op. cit. 24Comparisons among the survey years can be more appropriately made using internal ratios (e.g., quantity of offsite-produced energy per

value of shipments) because the coverage differences will appear affect both energy consumption and value of shipments equivalently in a given

year. Indeed, for that reason the adjustment factor in the 1988 survey was not a factor in comparing energy intensity change estimates. See

Energy Information Administration, Manufacturing Energy Consumption Survey: Changes in Energy Intensity in the Manufacturing Sector, 1980-

1988, DOE/EIA-0552 (80-88).

25The RSE targets were not input directly into formulas and algorithms usually used in allocating sample cases according to probabilityproportional-to-size sampling. Sample was allocated according to what was expected to achieve the specified targets. If tests on achieved RSE’s

of correlated ASM measures were not obtained, samples would have been re-allocated. This proved unnecessary.

440 Energy Information Administration/Manufacturing Consumption of Energy 1991
The major purpose of increasing the sample size was to be able to produce separate energy estimates for more

industries than before. The previous two surveys published estimates for the 20 major groups that comprise

manufacturing and 10 four-digit industries. Those 10 four-digit industries were the most energy-consuming in

manufacturing. The 1991 MECS has 40 four-digit industries, 2 three-digit industry groups, and 20 major groups.

The industry additions come from three groups: (1) industries not in the top 10, but with high energy consumption;

(2) certain high-growth industries such as computers and medical instruments; and (3) industries for which there are

identifiable policy interests or conservation opportunities.

The increase in sample size also allowed for greater reliability of existing estimates, especially among the major

groups (two-digit SIC’s). For example, SIC 20 in the current sample design includes eight four-digit industries for

which estimates were publishable. Previously, in the 1985 and 1988 designs, no four-digit industries in SIC 20 were

published separately. The addition of the eight industries in 1991 yielded greater reliability of the SIC 20 major

group estimates by having more sample cases in the publishable four-digit industries that comprise SIC 20. Thus,

overall reliability in SIC 20 was improved without adding sample cases for that express purpose.

Sampling Methodology

The selection of the MECS sample was a two-stage selection process, with the first stage being the selection of the

ASM mail sample from the CM frame. The second stage was the subselection of the MECS sample from the ASM

mail sample. Thus, a MECS sample establishment is selected conditionally upon it having been selected into the

ASM mail sample, which means that its probability of selection from the ASM sample is conditional. Therefore,

the overall probability of selection into the MECS sample is represented by the product of this conditional probability

and its ASM selection probability.

The probabilities for selection into the MECS sample are proportional to an energy measure of size (MOS).

Calculations of the MOS are different from previous years, although closely related. Actually, two MOS’s were

computed for each establishment. The first was based on the 1990 ASM purchased electricity quantity. The other

was based on the ASM cost of purchased fuels (excluding electricity). The probability of selection would be the

maximum of the two probabilities computed using the two different MOS’s.

The energy MOS for the 1985 and 1988 surveys was formed by taking a previous total Btu measure per cost of fuels

and electric energy at the establishment updated by multiplying that ratio by a more current measure of average cost

of fuels and electric energy. If the establishment had come into existence since the time of the last energy data

available, industry averages would be employed for the ratio of Btu to cost of fuels. Neither MOS in the 1991

MECS is as highly correlated with energy consumption as the MOS used in the 1985 and 1988 sample designs.

However, one advantage of the 1991 method is the fact that ASM data are used directly. Thus, each establishment

has its own MOS and industry averages are no longer needed.26

The MECS sample for the 42 separately published three- and four-digit industries included 100 percent of the

corresponding ASM mail sample, with four exceptions. This was done to maximize reliability (i.e, minimize the

standard errors) for those important energy-intensive and growth industries. However, four of those industries had

such a large ASM sample it was impractical to include all of the establishments. Those industries were SIC 2051,

"Bread, Cake, and Related Products"; SIC 2813, "Industrial Gases"; SIC 308, "Miscellaneous Plastic Products, not

otherwise classified"; and SIC 3714, "Motor Vehicles Parts and Accessories." The number of cases included in the

MECS sample was large enough to ensure sampling errors of less than 5 percent as measured on certain ASM

variables.27

26By using two different probabilities of selection, the expected sample size would be larger than would be expected by using only one. The

sample allocations for each stratum were adjusted as necessary to stay close to the EIA targeted sample sizes. 27The MECS sample design was tested using 1990 ASM data. After the sample was selected, relative standard errors (RSE’s) were computed

with the MECS sample using energy related measures such as cost of fuels and purchased electricity quantity.

Energy Information Administration/Manufacturing Consumption of Energy 1991 441
The remaining establishments were sampled from the 20 two-digit groups in a pattern designed to keep sampling

errors within pre-established bounds for estimates of total consumption and consumption of four major types of

energy: electricity, natural gas, coal, and the aggregate of all other types. The procedure for subselecting ASM

sample establishments into the MECS sample were such that their overall probabilities of selection for the MECS

were proportional to an estimated energy MOS. The overall probabilities for selection of the MECS sample

establishments ranged from 0.002 to 1.000.

The total sample size actually selected was 16,054. Of these 305 establishments were determined to be out-of-scope

or no longer in business prior to the MECS mailing, leaving a mail sample of 15,749. At the final closing, 14,299

questionnaires were received, a response rate of 91 percent.

Fieldwork, Editing, and Quality Control

The 1991 MECS continued the method that was started with the 1988 survey of using customized questionnaires for

specific industries. The three questionnaires were:

• Form EIA-846(A).—This questionnaire was sent to the majority of the sample and collected the basic

consumption, expenditure, fuel-switching, end-use, and technology information.

• Form EIA-846(B).—This questionnaire was sent exclusively to establishments in the Petroleum

Refining Industry (SIC 2911). The design of the questionnaire took advantage of the fact that other

EIA surveys collect certain consumption and expenditure data from the refinery population. Thus, the

EIA-846(B) did not require respondents to report on particular data items.

• Form EIA-846(C).—This questionnaire was sent to producers of Chemicals and Allied Products (SIC

28), producers of Petroleum and Coal Products other than Petroleum Refining (SIC 29 excluding SIC

2911), Lumber and Wood Products (SIC 24), Paper and Allied Products (SIC 26), and selected

Primary Metals Industries (in SIC 33). It is similar to the EIA-846(A) except that it collects additional

information on shipments of energy sources produced onsite and a different set of specific technologies

related to energy efficiency.

The questionnaires were mailed to the in-scope MECS sample establishments in two groups. The first group

consisted of those companies that only have establishments receiving the EIA-846(A). They were mailed the

questionnaires on February 24, 1992. All other companies were mailed the questionnaires on March 17, 1992.28

Returned questionnaires were subjected to initial screening procedures for completeness, and incomplete forms or

responses with obvious inconsistencies were set aside for review by industry specialists. Valid returned

questionnaires were forwarded directly to check-in and then to data entry.

All forms that were incomplete or failed the initial screening procedures were carefully reviewed by the industry

specialists from the Census Bureau and EIA. These specialists retrieved missing data and verified questionable items

by telephone contact with the individual who completed the questionnaire. Once the forms were completed and

verified, they were forwarded to check-in and to data entry.

The resulting MECS data file was then subjected to a series of computer edits. Those edits included consistency

checks among data items from different parts of the MECS and between the MECS and the 1991 ASM, as well as

checks for outliers in the distribution of individual variables. Records with failed edits were reviewed and followed

up by industry specialists.

28The MECS sample is selected according to establishment characteristics. However, the central administrative offices of multi-establishment

companies were the addressees of the questionnaires and were responsible for distributing them to their establishments.

442 Energy Information Administration/Manufacturing Consumption of Energy 1991
Development of the Data File

The estimates in this report were developed from a data file consisting of both directly reported values and more

complex items derived from a combination of directly reported values. Reported values consist of responses to the

1991 MECS questionnaires (Appendix F). Those values were supplemented by estimates of energy consumption

for nonfuel purposes and offsite-produced fuel consumption at petroleum refineries from another EIA

questionnaire.29 Additionally, the responses to the questionnaire for each responding establishment were

supplemented by the following economic data:

• Value of shipments and receipts

• Value added by manufacturing

• Total employment.

These economic data were not collected by the 1991 MECS but were provided by the Census Bureau by linking the

1991 ASM economic data and MECS energy data at the establishment level.

The reported energy values were used to construct several derived values, which, in turn, were used to prepare the

estimates appearing in selected tables in this report (See "Survey Estimates" section in this appendix.) These derived

values are defined as follows:

1. Energy produced offsite and consumed as a fuel. This derived value represents onsite consumption of

fuels that were originally produced offsite. That is, they arrived at the establishment as the result of a

purchase, or were transferred to the establishment from outside sources. As such, this derived value is

equivalent to "consumption of purchased" fuels as reported by the Census Bureau for the years 1974-1981.

The Census Bureau defines "purchased" fuels to include those actually purchased plus those transferred in

from other establishments.30

2. Energy produced offsite and consumed for nonfuel purposes. This derived value also represents energy

that was originally produced offsite. This energy was used at the establishment site as raw material inputs

and feedstocks.

3. Energy produced onsite from nonenergy inputs and consumed onsite as a fuel. This derived value covers

materials such as wood chips, bark, and wood waste, and pulping liquor. These fuels are produced primarily

in pulp and paper mills as a byproduct of wood used in the pulping process. Wood for pulping is not

classified as energy in the MECS, and, therefore, would not have been included as an input. This derived

value also covers waste materials, biomass, and hydrogen that was produced from the electrolysis of brine.

Energy sources such as petroleum and coal that were consumed as fuel and originated onsite from captive

mines or wells (an unusual occurrence) are included here also.

4. Energy produced onsite from nonenergy inputs and consumed for nonfuel purposes. Most

onsite-produced energy that is used for nonfuel purposes is derived from other types of energy. The major

exception is hydrogen that is produced from the electrolysis of brine. Hydrogen produced in this manner and

used for nonfuel purposes is the major occurrence of this derived value. Energy sources such as petroleum

and coal that were consumed as a nonfuel and originated onsite from captive mines or wells are included here

also.

5. Energy produced onsite from energy inputs and consumed as a fuel. This derived value covers a wide

range of fuels consumed onsite that are produced onsite as direct products or byproducts of other types of

energy.

29The calculations for these quantities are discussed in the sections of this appendix titled, "Consumption for Nonfuel Purposes at Refineries"

and "Offsite-Produced Fuel Use at Refineries." 30U.S. Department of Commerce, Bureau of the Census, Annual Survey (Census) of Manufactures, "Fuels and Electric Energy Consumed,"

1974-1982 (Washington, DC).

Energy Information Administration/Manufacturing Consumption of Energy 1991 443
6. Energy produced onsite from energy inputs and consumed onsite for nonfuel purposes. This derived

value includes all petrochemical feedstocks and other raw material inputs that were produced onsite from

existing energy or from other onsite-produced energy.

7. Energy produced onsite from energy inputs and shipped to other establishments. This derived value

is new to the 1991 MECS. Data are now collected for certain industries that produce and sell energy sources

to other establishments. Most notably, these industries include Blast Furnaces and Steel Mills (SIC 3312)

and various industries in Chemicals and Allied Products (SIC 28). If an establishment converts an energy

source into a fuel and then ships it offsite to another establishment, the total Btu quantity among the

producing and receiving establishments would be duplicative and thus overstated. By deducting this derived

value from the producing establishments, the amount consumed at the receiving establishments would not be

duplicative.

The first four of those derived values represent an addition to the energy consumed onsite, and are described in this

publication as primary consumption (that is, either they were produced offsite or were produced onsite from

nonenergy inputs). The fifth derived value described above does not represent an addition because it was produced

onsite from energy that is already reported as input. Such energy represents duplicate counting of the input energy

content. It is, however, a useful measure of onsite-produced fuel consumption and is not duplicative with respect

to an estimate of total fuel consumption. The sixth derived value is duplicative with respect to the consumption of

energy for nonfuel purposes, and, therefore, was not used to prepare estimates. It was included only for

computational purposes and completeness. The seventh derived value appears as a special table in this appendix and

is used to adjust primary consumption. The adjustment was excluded from the detailed statistical tables (e.g., Table

A1) so that continuity would be maintained with previous estimates of primary consumption.

Assumptions Underlying Derived Values

Two basic assumptions are necessary to produce the derived values from the data reported on the MECS

questionnaire. First, it is assumed that any energy produced onsite is disposed of as it is produced. That is, it is

burned as a fuel and/or consumed as an input or feedstock; any excess is flared, dumped, transferred-out, sold, or

is placed into inventory. For the purpose of computing the derived values, a quantity of an energy source produced

onsite and placed into inventory during the previous year is not considered onsite production in the reporting year.

A corollary of this assumption is that any energy source that was consumed onsite and originated offsite was

acquired only if there was not sufficient onsite production to meet the establishment’s needs of the energy source

in the current year. Second, it is assumed that the priority use of onsite production is first as a shipment (if

applicable), then as an input or feedstock, and last as a fuel. These assumptions are believed to reflect the energy

use patterns at the vast majority of, but not all, establishments. The assumptions do provide a consistent method of

determining an establishment’s nonduplicative total energy consumption and its reliance on outside providers to

supply it.

The Estimation Process

Estimates in this report represented 98 percent of the of manufacturing payroll and shipments in the CM universe.

Coverage was equivalent to the 1991 ASM mail file. The two percent not covered are the smallest manufacturing

establishments that were not sent an ASM form. ASM imputes those establishments’ data for publications by using

industry averages. As discussed previously, the MECS no longer covers the small establishments either directly or

through a ratio adjustment.

Population representation is accomplished by weighting the data from the establishment records in the consumption

data file. Weighting is the process of multiplying the reported or derived values by a case-specific constant designed

to inflate the data from each sample case to that portion of the population that it represents. The first, basic

component in the MECS weights is the sampling weight. The sampling weight for a MECS sample case is the

reciprocal of its overall probability of selection into the ASM and subsequent selection for the MECS.

444 Energy Information Administration/Manufacturing Consumption of Energy 1991
The second component of the MECS weights is an adjustment for nonresponse. Adjustment factors to account for

nonresponse were calculated by using the known energy measures of size of the respondents and the total sample.

Because an establishment is selected into the MECS sample with a probability proportional to the establishment’s

energy measure of size, that measure can be viewed as an establishment’s estimated contribution to energy

consumption in 1991. A separate adjustment factor was computed for each of the 62 sampling strata31 and took

the form:

(1)

where MOSs,j is the measure of size for MECS sample establishment j in stratum s, and MOSs,i is the measure of size

for MECS respondent i in stratum s.

32 The adjustment factor was then multiplied by the sampling weight to

produce the final MECS weight.

Feedstocks and Offsite-Produced Fuel at Petroleum Refineries

The basic function of a petroleum refinery (SIC 2911) is to manufacture a wide variety of petroleum products from

crude oil and other liquid hydrocarbon inputs. Those products can be grouped into three classes of use. The largest

portion of refinery output is in the form of fuels that are ultimately consumed strictly for their energy content (e.g.,

motor gasoline, kerosene, and diesel oil). Many refinery products, however, are consumed, not for their energy

content, but for their chemical properties. This class of energy products is generally known as petrochemical

feedstocks. Finally, a third class of products consists of finished materials that are consumed for specific physical

properties, rather than for their energy content or chemical properties. Those finished materials include asphalt,

lubricants, waxes, and solvents, and are referred to as nonenergy products.33

The MECS was specifically designed to collect information on the consumption of energy for heat, power, and

electricity generation, and as petrochemical feedstocks and other raw material inputs. The consumption of energy

was reported directly by the establishments in the MECS sample, and the estimates in this report reflect that

consumption. For most industries, the end result of energy inputs is manufactured products that are not considered

energy products. However, fuels and some petrochemical feedstocks produced from refinery inputs are treated as

energy products by their subsequent users34, and are reported not only in other manufacturing industries, but also

in EIA surveys of consumption in other end-use sectors (residential households, residential vehicles, and commercial

buildings). In that sense, refineries do not "use up" the majority of their inputs. They merely convert them from

one form of energy (for example, crude oil) to another more usable form (for example, motor gasoline). Therefore,

classifying refinery inputs that go into fuels and certain petrochemical feedstocks as refinery consumption would have

resulted in massive double counting of total energy consumption, both within the manufacturing sector, and across

other energy-consuming sectors in the U.S. economy.

31For the 1985 MECS, adjustment cells were defined by cross-classifying sampling stratum with levels of employment size category.

Employment size proved not to be worthwhile in using as an adjustment factor and was discontinued in later surveys. 32Although there were two measures of size used, it was necessary to select only one measure to form the nonresponse adjustment. The

measure chosen was one that combined the two: it was the 1991 ASM cost of combustible fuels plus the cost of electricity. 33Certain petroleum products can be classified according to the end user of the product. For example, propane might be a fuel or a feedstock

depending on the needs of the receiving establishment. 34Whether a respondent reports a petrochemical feedstock as an energy source receipt often depends on the type of feedstock received. If

the feedstock received is commonly used as a fuel, such as distillate fuel oil or ethane, then it is assumed that respondents will report it as an

energy source receipt. If the refinery product received for petrochemical feedstock use is not normally considered a fuel, the assumption is made

that respondents would not report it as an energy source receipt.

Energy Information Administration/Manufacturing Consumption of Energy 1991 445
The third class of refinery products, nonenergy products, must be treated differently. The creation of those products

by the refinery also requires energy inputs, primarily crude oil. The products are combustible and have a known heat

content expressed in British thermal units (Btu). Asphalt, for example, contains 6.636 million Btu per 42-gallon

barrel. However, the products are not recognized as energy by their subsequent consumers, and no provision was

made for collecting data on their consumption from the MECS respondents. Therefore, the transformation of energy

inputs to nonenergy products must be counted as refinery consumption, or it will never be accounted for anywhere

in EIA’s consumption surveys.

One characteristic of petroleum refineries is that, except for losses caused by spills, contamination, etc., the Btu

content of the energy inputs exactly equals the Btu content of the outputs. Therefore, one only needs to know the

quantities of those nonenergy products that were shipped by a refinery in order to know the quantity of energy inputs

that was used to produce them. EIA produces such information for all refinery products from the "Monthly Refinery

Report," Form EIA-810. This form collects information on the monthly shipments from the universe of refineries

in the United States. These data were the basis for estimating the input energy requirements for the nonenergy

products.

The shipment quantities of the nonenergy products and certain classifications of petrochemical feedstocks, as reported

on the "Monthly Refinery Report," were converted to Btu and summed to produce a monthly refinery total. Those

totals were then summed across refineries and months to produce the total Btu value of refinery shipments of

nonenergy products for 1991. That total was used to represent the total Btu value of the inputs used to produce the

nonenergy products, and was inserted directly into the appropriate tables of this report to represent nonfuel

consumption in refineries. (See "Survey Estimates" in this appendix.) Because the individual energy inputs

corresponding to these shipments were not identified, the Btu value was entered in the "other" column.

The "Monthly Refinery Report" covers only the refinery part of an establishment while the MECS Forms EIA-846(A)

through (C) cover energy use at the entire site, as defined by the Bureau of the Census. This difference affects

MECS estimation only for cases in which a MECS report reflects energy use at both a refinery and a co-located

petrochemical plant. For these cases, establishment nonfuel use is not completely estimated by shipments of refinery

nonenergy products as measured by the EIA-810. The format of the MECS refining report, Form EIA-846(B) (see

Appendix F), allows respondents to report energy-related data from a petrochemical plant co-located with the

refinery. Form EIA-846(B) collected nonfuel use at and shipments of energy sources from the co-located

petrochemical plant (Columns 9 and 10 of Section II). The total Btu of the consumption as a nonfuel minus the

petrochemical plant shipments of energy sources is added across energy sources and establishments to the previously

discussed refinery shipments of nonenergy sources. Note that for the petrochemical plant, estimation of nonfuel use

is measured directly, as the majority of that usage does not appear in products that will later be converted to fuel

use by other manufacturing plants. The additional nonfuel use estimated for the adjoining petrochemical plants

proved to be small relative to the refinery usage because the majority of petrochemical plants report separately on

the MECS. Because the resulting quantities was unreliable35 and quite small compared to refinery shipments of

nonenergy sources, they were excluded from the total refinery nonfuel estimates.

The EIA-810 data are also used to calculate the offsite-produced fuel use at the refinery establishment. (See

"Derived Values" in this appendix.) Because Version A of Section II of Form EIA-846(B) collects only total fuel

use of petroleum products (regardless of their origin), it was necessary to use the EIA-810 data to calculate the

offsite-produced fuel ratio for those products. Estimation of the ratio utilized the same assumptions described in the

section on "Assumptions Underlying Derived Values" except that EIA-810 data were used instead. This ratio is then

applied to the MECS estimated value of total fuel.36 The estimator takes the form:

(2)

35Examination of the MECS refinery reports showed evidence that reporting for the adjoining petrochemical operations in the last two columns

caused considerable respondent confusion. 36The MECS value for total fuel would also include the amount used at the adjoining petrochemical plant if one were present. Using a ratio

based on refinery-only data from the EIA-810 on that portion of the establishment is a source of error. However, refinery fuel use will usually

dominate the petrochemical fuel use especially for petroleum products.

446 Energy Information Administration/Manufacturing Consumption of Energy 1991
where Op,MECS is the MECS estimate of the amount of petroleum product p produced offsite and consumed as a fuel,

Op,EIA-810 is the EIA-810 estimate of the amount of petroleum product p produced offsite and consumed as a fuel,

Fp,MECS is the MECS estimate of total fuel use of petroleum product p, and Fp,EIA-810 is the EIA-810 estimate of the

total fuel use of petroleum product p.

Estimates of the contribution to fuel consumption of offsite-produced nonpetroleum products are calculated directly

from MECS data, using the same method employed in other SIC’s.

Shipments of Energy Sources Produced Onsite

Manufacturers who produce energy sources do so not only for their own consumption but often sell or transfer the

products to other establishments. The most notable example in manufacturing is petroleum refineries. Energy

consumption for those establishments is estimated using a special method as has been explained in an earlier section.

The principal products of petroleum refineries are energy sources. Primary consumption in petroleum refineries, by

virtue of the special method already described, does not need to account for outgoing energy products since it

excludes incoming energy sources used for raw materials. Yet there are other types of manufacturers that produce

and sell energy sources as secondary products. If the energy content of the sold energy source materials from these

are counted at the producing establishment, there would be double counting when the energy source is counted at

the receiving establishment. Primary consumption, as currently defined, avoids double counting of intraestablishment use of an energy source which results from an onsite transformation from another energy source.

However, it may include double counting of inter-establishment use of such transformed energy sources. The 1991

MECS can further adjust primary consumption by deducting the amount of sold energy sources that were produced

onsite.

The example that has the greatest effect on total energy consumption is coal to make coke. A steel mill processes

coal to make coke for later use in the steel making process. Primary consumption counts the quantity of coal as the

original nonfuel input. Any onsite consumption of coke is not included in primary consumption as it duplicates the

coal use. It the steel mill sells and ships some of the coke to another establishment, it will show up as a shipment

of an offsite-produced energy source in the second establishment and will be included in primary consumption. That

would result in double counting. The double counting can be eliminated by subtracting the energy equivalent of coke

shipments from primary consumption.

Table B1. presents these shipment adjustments by SIC. The total shipments adjustment is 560.1 trillion Btu. That

means a better estimate of total primary consumption is 19,797 trillion Btu. However, if the purpose is to be

comparable with previous years, the original estimate of 20,257 trillion Btu should be used.

Table B1. Total Shipments of Energy Sources Produced Onsite from the Nonfuel Use of Other

Energy Sources, by Industry Group and Selected Industries, 1991

(Estimates in Trillion Btu)

SIC

Code Industry Groups and Industry Quantity Shipped

Total United States

28 Chemicals and Allied Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

2813 Industrial Gases ..................................................... W

2821 Plastic Materials and Resins ............................................. 3

2824 Organic Fibers Noncellulosic ............................................. W

2865 Cyclic Crudes and Intermediates .......................................... W

2869 Industrial Inorganic Materials ............................................. 221

29 Petroleum and Coal Products (excluding Refining) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

3312 Blast Furnaces and Steel Mills ........................................... 248

Total ............................................................... 560

Source: Energy Information Administration, Office of Energy Markets and End Use, Energy End Use and Integrated Statistics

Division, 1991 Manufacturing Energy Consumption Survey.

Energy Information Administration/Manufacturing Consumption of Energy 1991 447
Concept of Fuel-Switching Capability

EIA continues to employ the concept of fuel-switching that was developed prior to the 1985 survey. After extensive

consultation with potential data users and data providers for the 1985 survey, EIA developed a tightly-specified

concept of fuel-switching capability based on the following set of principles:

• Switching data would cover consumption of energy for heat, power, and onsite electricity generation only.

Switching of energy consumed as feedstock or raw material inputs would not be considered.

• Switching data would focus on capability (what could be done) rather than actual performance (what was,

or is being done) or future possibilities (what might be possible).

• Switching capability would be collected for a closed historical reference period, rather than the present, or

some future reference period.

• Switching capability would be collected for the one-year reference period used for MECS consumption data,

to tie in with the consumption data and avoid seasonal bias.

• The survey would measure short-term response capability; that is, actions that could have taken place within

30 days of a decision to switch.

• Switching capability would reflect the total flexibility provided by an establishment’s equipment configuration.

Both multiple-fired equipment and redundant or backup equipment could contribute to capability.

• The survey would measure in-place capability; that is, capability provided by equipment that was already

installed, or was available at the establishment for installation during the reference period. Major

modifications to the design capabilities of equipment and major capital expenditures were not to be considered

in assessing capability.

• Switching capability would be valid only if, following the switch from one type of energy to another, the

establishment would have been able to maintain its actual production schedule during the reference period.

• Switching capability provided by an establishment’s equipment configuration could be limited or negated by

legal or practical constraints such as binding supply contracts, interruptible service, environmental regulations,

or unavailability of supply or delivery systems for a potential alternative.

• Economic considerations were not to be considered a practical constraint in evaluating switching capability.

The survey was designed to measure potential response to changes in economics or supply patterns.

The MECS obtained fuel-switching data by asking respondents to determine the amounts of 1991 input energy

consumption of six major types of energy that could have been switched to one or more alternatives in accordance

with the previously listed principles. The six types of energy were purchased electricity, natural gas, distillate oil,

residual oil, coal (excluding coke),37 and LPG. Respondents were directed to provide the quantities of switchable

consumption by subtracting the quantities that were not switchable from the quantities that were actually consumed

during 1991. Such an approach is clear and saves burden because it starts with a previously-reported quantity and

allows the respondent to subtract quantities known to be nonswitchable because of any one of the various conditions

discussed above. The alternative would be to force the respondent to add up quantities for all energy uses for which

all aspects of the concept are satisfied. Once the total switchable quantities had been determined, the remaining task

was to determine how much of each switchable quantity could have been replaced by specific alternatives.

37The exclusion of coke from the coal was a change from previous MECS years. It was excluded because coke was found to be virtually

nonswitchable in its most common use, the production of steel.

448 Energy Information Administration/Manufacturing Consumption of Energy 1991
How To Measure Discretionary Fuel Use

One of the more interesting summary statistics that can be developed from the estimates of actual consumption,

minimum consumption, and maximum consumption is the discretionary-use rate. The discretionary use rate is a

measure, in percent, of the extent to which manufacturers elected to consume discretionary quantities of a given

energy source.

The discretionary-use rate is calculated as:

(3)

where USE is the discretionary use rate of a given energy source,

ACT is the actual consumption of that energy source,

MIN is the minimum consumption, which would have been achieved if all ascertained switching from that

type of energy had occurred.

and MAX is the maximum consumption, which would have been achieved if all ascertained switching into that

type of energy had occurred.

Thus, the discretionary-use rate is a measure of the depth, in percent, into the discretionary range of consumption

to which manufacturers chose to go, given their fuel-switching capabilities and production levels of 1991.

If manufacturers had chosen to minimize their consumption of a given energy source by using alternative energy

sources whenever possible, then ACT = MIN, and the discretionary-use rate would be 0 percent. At the other

extreme, if manufacturers had chosen to maximize the consumption of a given energy source by using that energy

source whenever possible, then ACT = MAX, and the discretionary-use rate would be 100 percent.

Note that (ACT - MIN) is equivalent to the "switchable" amount of the given energy source that was consumed, that

is, the amount of the energy source that was consumed even though it could have been switched to another energy

source.

Survey Estimates Presented in Appendix A

Except for some estimates of energy consumption for nonfuel purposes at petroleum refineries, all energy

consumption and energy-related statistics produced from MECS data are calculated by inflating the data collected

from the responding establishments with the adjusted sampling weights. These weights establish the relationship

between the responding establishments and the manufacturing population as defined for the MECS. Two types of

statistics are shown in this report: aggregates (for example, total natural gas consumption in the hydraulic cement

industry), and ratios (for example, the amount of fuel consumed per dollar of value added in the manufacturing

sector). These statistics are based on the originally reported values, or the derived values discussed earlier, and

appear in Tables A1 through A58.

Primary Consumption for All Purposes

Tables A1 and A9 present estimates of the total primary consumption of energy for all purposes by the

manufacturing sector. This measure is intended to represent total demand for energy by manufactures.38 Except

for petroleum refineries, the estimates in Tables A1 and A9 are based on the following derived values:

38Note that the word "primary" in the MECS usage refers to the first use of energy at a manufacturing site. It has nothing to do with

accounting for energy losses in generating and transmitting electricity. That usage is embodied in the term "primary energy," commonly used

in EIA to indicate energy measures that take such losses into account. All energy estimates in MECS that include electricity consumption use

its end-use conversion value, 3412 Btu per kWh.

Energy Information Administration/Manufacturing Consumption of Energy 1991 449
• Energy produced offsite and consumed as a fuel

• Energy produced offsite and consumed for nonfuel purposes

• Energy produced onsite from nonenergy inputs and consumed as a fuel

• Energy produced onsite from nonenergy inputs and consumed for nonfuel purposes.

They also include estimates of net electricity and steam consumption; that is, purchases plus transfers in and

generation from noncombustible renewable resources, minus quantities sold and transferred out. Primary

consumption excludes quantities of energy that were produced from other energy inputs and, therefore, avoids intraestablishment double-counting.

The estimates shown in the petroleum refinery row of Table A1 are conceptually different from the estimates in the

other rows of that table. For all industries except petroleum refineries, each cell represents the total primary

consumption of energy for all purposes. In the petroleum refinery row, the cell entries for "net electricity" through

"coke and breeze" represent only the quantities of given type of energy that was consumed as a fuel. The "other"

cell of the petroleum refinery row includes other energy that was consumed as a fuel plus the quantity of energy

(mostly crude oil) that was consumed for the production of nonenergy products, as estimated by the Btu value of

the shipments. Note that although the estimates shown in the refinery row are computed differently, the total Btu

does represent a nonduplicative measure of primary consumption. (For more information, refer to "Feedstocks and

Offsite-Produce Fuel at Petroleum Refineries" in this appendix.)

Table A9 shows primary consumption for all purposes by economic characteristics of the establishment. In that

table, the cell in the row entitled "not ascertainable" and the column labeled "other" contains the total quantity of

energy consumed for the production of nonenergy products by refineries. The quantities of energy consumed for

the production of heat and power in refineries are included throughout the remainder of the table, depending on the

value of shipments or employment size of the responding establishment.

Primary Consumption for Nonfuel Purposes

Tables A3 and A11 present the total primary consumption of combustible energy for nonfuel purposes. These tables

are based upon aggregates of the derived values of energy produced offsite plus those produced onsite from

nonenergy inputs, and consumed onsite for nonfuel purposes. Tables A3 and A11 present the nonfuel primary

consumption component of Tables A1 and A9. The entry in the "other" column of the petroleum refinery row of

Table 2 represents the total inputs (mostly crude oil) for the production of nonenergy products. The other cells in

the petroleum refinery row contain zeros because refinery inputs are available in aggregate form only.

Except for petroleum refineries (see "Feedstocks and Offsite-Produce Fuel at Petroleum Refineries" in this appendix),

the estimates in Tables A3 and A11 are based on the following derived values:

• Energy produced offsite and consumed for nonfuel purposes

• Energy produced onsite from nonenergy inputs and consumed for nonfuel purposes.

Input Energy for Heat, Power, and Electricity Generation

Tables A4 and A12 present estimates of input energy for the production of heat, power, and electricity generation.

For combustible energy, the estimates are based upon the reported MECS questionnaire responses to "Quantity

consumed onsite as a fuel" (see Appendix F). That reported value is exactly equal to the sum of the following

derived values:

450 Energy Information Administration/Manufacturing Consumption of Energy 1991
• Energy produced offsite and consumed as a fuel

• Energy produced onsite from nonenergy inputs and consumed as a fuel

• Energy produced onsite from energy products and consumed as a fuel.

Thus, the estimates of combustible energy in Tables A4 and A12 represent total consumption as a fuel, regardless

of where the energy was produced.

The consumption estimates for fuel use are not duplicative. There is clearly no duplication for quantities that were

produced offsite as well as for those produced onsite from nonenergy sources. Quantities produced onsite from other

energy inputs result from consumption of an energy source as a feedstock or raw material input. They do not result

from the consumption of an energy as a fuel.

Examples of energy produced onsite from other energy sources include,

• Coke oven gas produced as a byproduct of the destructive distillation of coal to produce coke

• Petroleum coke produced in refineries as a result of the high temperature treatment of petroleum fractions

• Still gas produced in refineries as a result of distillation, cracking, reforming, and other processes.

From those examples, it is clear that the input energy was not consumed as a fuel and would not have been included

elsewhere in Tables A4 and A12.

The estimates of electricity and steam (note that steam is included in the "other" energy category) must conform to

the same criteria as combustible energy. That is, they must represent inputs to produce heat and power, and to

generate electricity that do not duplicate energy content represented elsewhere in Tables A4 and A12.

In the case of electricity, the quantities generated onsite by conventional generation or cogeneration must be excluded

because the input fuels to produce the electricity (coal, for example) are already counted elsewhere in the table.

Thus, the nonduplicative measure of electricity input for Tables A4 and A12 is the same net electricity estimate that

appeared in Tables A1 and A9. The same rationale applies to steam. Onsite production is excluded because the

input fuel would be counted elsewhere. Thus, the allocation of energy to the various sources shown in Tables A4

and A12 is consistent with a concept of "first use" of energy for heat, power, and electricity generation.

Other Topics

Tables A5 and A13 present the total consumption of offsite-produced energy sources as a fuel. As noted, these

estimates are approximately definitionally equivalent to the Census Bureau’s "purchased" fuels.

The estimates in Tables A5 and A13 are based on the derived value, energy produced offsite and consumed onsite

as a fuel.

Tables A2 and A10 present consumption estimates of selected petroleum products expressed in barrels per day rather

than in barrels. Included are three estimates of consumption that have been described previously: (1) primary

consumption (Table A1), (2) total input energy (Table A4), and (3) consumption for nonfuel purposes (Table A3).

These estimates are presented for the convenience of the data user and were derived simply by taking the annual

consumption estimate and dividing by 365.

Table A6 presents quantities of total inputs of byproduct and "other" energy sources used for heat, power, and

electricity generation. These estimates are components of the estimates of combustible energy sources found in the

last column of Tables A4 and A12. Net steam (see explanation for Tables A4 and A12) is not included in Table

A6 but is included in the "Other" column in Tables A4 and A12.

Energy Information Administration/Manufacturing Consumption of Energy 1991 451
Tables A7 and A14 present total shell storage capacity of residual oil, distillate oil and motor gasoline. Shell storage

capacity includes all onsite capacity, including that which is dedicated or leased for storage of energy owned by other

establishments.

Tables A8 and A15 present estimates of several energy-related operating ratios. These estimates are computed from

energy data reported by the MECS responding establishments and economic data reported on the ASM for the same

establishments. The consumption values used in the formation of these ratios appear in Tables A4 and A12. It is

not possible to exactly reconstruct the 1991 ASM estimates of economic variables by dividing MECS consumption

by corresponding ratios of consumption per economic unit. Due to different purposes of the MECS and ASM, the

size and weighting scheme of the MECS and ASM samples are different. Therefore, a MECS estimate for an

economic variable would be expected to be slightly different due to sampling error, especially for the entries

representing a relatively small number of establishments.

Tables A16 and A19 present components of electricity demand. These quantities are calculated directly from

responses to the MECS questionnaire. Note that the quantity "net demand for electricity" is not equivalent to "net

electricity" shown in Tables A1, A4, A9, and A12. The latter quantity excludes onsite generation by combustible

energy sources.

Tables A17 and A20 present components of onsite electricity generation. These components are cogeneration,

generation using renewable energy sources, and conventional generation using combustible energy sources. These

data are weighted totals of reported responses.

Tables A18 and A21 present quantities of electricity sold to utility and nonutility purchasers. These data are

weighted totals of reported responses.

Tables A22 through A29 present purchases, expenditures, and average prices for energy sources. The purchased

quantities shown in Tables A22 and A26 are not values of consumption. These data are the amounts actually

purchased in the open market regardless of their later disposition. Quantities received through transfers or from a

central purchasing office are excluded. The prices shown in Tables A25 and A29 are the results of simple division

of the expenditures presented in Tables A25 and A28 by the purchased quantities in Tables A22 and A26. Prices

are shown in both dollars per physical unit and dollars per million Btu. Both the expenditures and quantities

purchased were values estimated directly from responses to the MECS questionnaires.

Tables A23, A27, and A46 through A49 present purchases, expenditure, and price tables for electricity, natural gas,

and steam. These tables break down the gross purchases for these energy sources by the type of supplier. Electricity

and steam suppliers are either utilities or nonutilities. The classifications of the natural gas suppliers are utilities,

transmission pipelines, and other suppliers.

The increase in sample size yielded other benefits besides increases in separately publishable SIC’s and data

reliability. There are now enough sample cases to support two-way categorizations of data that were not possible

previously. Tables A30 through A32 present three different measures of energy consumption by SIC and value of

shipments category. Tables A33 through A35 present the same consumption measures by SIC and categories of total

employment.

Tables A36 through A39 are presentations of results from questionnaire items new to the 1991 survey. Respondents

were asked to assign their total input energy consumption of selected major energy sources to various end uses in

the establishment. The energy consumption measures used as a baseline for each combustible energy source are

found in Tables A4 and A12. They are shown in Tables A36 through A39 as the line item, "Total Inputs."

Electricity end-use data were collected on the MECS questionnaire as net demand for electricity (purchases plus

transfers in plus onsite generation minus sales and transfers out). Those estimates first appear in Tables A16 and

A19 and were collected for end-use data because quantities of net demand represent the actual amount available for

use at the establishment. Tables 38 and 39 show the results using that measure of electricity consumption.

452 Energy Information Administration/Manufacturing Consumption of Energy 1991
Net demand for electricity duplicates the fuel consumption of combustible energy sources used in the process of

electricity generation. Tables A36 and A37 show the end-use estimates using the concept of net electricity. Net

electricity, the concept used in conjunction with "Primary Consumption" and "Total Inputs of Energy For Heat Power

and Electricity Generation" is defined as the sum of purchases and transfers in plus onsite generation from

noncombustible renewable resources minus sales and transfers out. Unlike net demand for electricity, net electricity

excludes onsite generation of electricity from combustible energy sources. Thus, it does not double-count the energy

content of combustible energy sources used to generate electricity. End-use consumption in terms of net electricity

was calculated by forming ratios of net demand for electricity for each end-use to total net demand for electricity

at the establishment, and multiplying those ratios by the quantity of net electricity at the establishment.

The total inputs row in tables A36 and A37 include a category "Other" to show how much of the total input energy

is not accounted for by major energy sources. For some SIC’s it is a substantial amount. For example, coal coke

and refinery off-gas are significant contributors to boiler fuel and process heat. Data are not available to break down

the "other" category by end-use. Further, steam (the major output from boilers) is excluded from these tables.

Consequently, total input energy for any end-use category other than boiler fuel would be underestimated by the

amount of steam that contributes to that end-use.39 Therefore, summing consumption over the end-use categories

for which data are available would give a misleading indication of the energy actually used.

For any individual energy source, the estimates in the end-use categories represent direct use. When electricity is

considered independently of the combustible energy sources, the more meaningful amount would be in terms of net

demand (Tables A38 and A39) rather than net electricity (Tables A36 and A37).

Tables A40 and A41 present estimates of participation by establishments in energy management activities. Total

input energy is the measure of interest. If an establishment indicates participation in an activity, its energy

consumption is counted in the appropriate category. If not, it is counted in "None Identified."40 Table 40 also

shows subcategories of participation: utility/supplier sponsorship (often referred to as Demand-Side Management),

own or third-party sponsorship, or a mixture of both.

Tables A42 through A44 present estimates of total input energy consumption broken down by SIC, establishment

size, and presence of selected energy-saving technologies. These technologies are known to save energy but may

not have been installed for that purpose.

Tables A45 presents estimates of total input energy consumption by floorspace square-footage category, percent of

heated and/or cooled space, and presence or absence of computer controls for building environment. All three of

these items are new to the 1991 MECS.

Tables A50 and A51 are new to the 1991 MECS. They present the operating ratios shown in Tables A8 and A15

but broken down further into both SIC and category of value of shipments (Table A50) or category of total

employment (Table A51). These tables are now possible due the increased MECS sample size.

Table A52 presents estimates of nonswitchable minimum requirements and the maximum consumption potential of

the different types of energy covered specifically by the fuel-switching section of the MECS. An estimate of the

actual consumption of each type of energy is provided as a reference point. That consumption estimate represents

the quantity that was consumed onsite for the production of heat, power, and the generation of electricity in 1991.

The estimates are identical to the ones found in Table 4, except for estimates of electricity. For fuel-switching, the

electricity quantity considered is electricity receipts found in Table 5. (The reasons for using electricity receipts are

described below in the discussion of Tables A53 through A58.)

39In the case of cogeneration, the underestimation could be expressed in terms of an unknown amount of steam and electricity.

40The MECS sampling method efficiently estimates energy consumption but not establishment counts. Therefore, energy consumption was

chosen as the measure of participation rather than number of participating establishments.

Energy Information Administration/Manufacturing Consumption of Energy 1991 453
One of the purposes of Table A52 is to provide an estimate of the smallest possible quantity of a given type of

energy that would have been required in 1991 (keeping production constant), if all possible ascertained switching

away from that type of energy had taken place. The quantities given in the minimum consumption column of Table

A52 are likely to be higher than the true minimum energy requirements because they include the quantity of 1991

consumption for which switching capability was not ascertained. Some unknown proportion of this latter quantity

could likely have been replaced.

Table A52 also provides estimates of the maximum energy consumption that would have been possible if all

ascertained switching to that type of energy had occurred. The estimates assume that all indicated substitutions were

simultaneously possible and the substitutable amount consists of the sum of all possible switches to the designated

type of energy. An assumption of this kind is necessary because there is no specified limit to a respondent’s ability

to switch into an energy source. Note that there is a given limit to a respondent’s ability to switch out of an energy

source provided by the third row of the fuel-switching section of the MECS questionnaire (see Appendix F,

Manufacturing Energy Consumption Survey Forms).

Tables A53 through A58 present estimates of the capability of substituting specific alternative types of energy for

those actually consumed, holding production constant. Each table contains information for the specific type of energy

that was actually consumed for the production of heat, power, and generated electricity in 1991. It should be noted

that the first column of Table A53 refers to "total receipts" of electricity, while the first column of Tables A54

through A58 refers to "total consumed" natural gas, distillate fuel oil, residual fuel oil, coal, and LPG, respectively.

Thus, the quantities of electricity generated onsite are excluded as are the quantities of electricity leaving the

establishment site. When considering fuel-switching capabilities, total electricity receipts is a more meaningful

quantity than total electricity consumption. A respondent who has onsite generation of electricity has, more than

likely, used an additional amount of a combustible energy source to operate the generator. It is a valid question to

ask, "How much of that self-generation is replaceable by electricity receipts?" However, it is more reasonable and

of greater interest to collect the fuel-switching data for the fuel used to generate the electricity by asking respondents

to show the quantity of electricity receipts that could replace the combustible fuel.

In Tables A53 through A58, the estimates provided in each column under "alternative types of energy" should be

considered independently because respondents were instructed to enter the maximum amount of the quantity of the

energy actually consumed which could have been replaced by a given alternative. For example, Table A53 shows

that for Paper and Allied Products (SIC 26), a total of 3,181 million kilowatthours (kWh) of electricity receipts was

switchable. Natural gas could have replaced 1,406 million kWh of that quantity. The other replacement quantities

were distillate fuel oil, 576 million kWh; residual fuel oil, 649 million kWh; coal 859 million kWh; LPG, 128 million

kWh; coal coke and breeze, 47 million kWh; and other fuels, 230 million kWh. Because each value represents the

maximum quantity of electricity receipts that could have been replaced, their sum exceeds the total quantity of

electricity that was ascertained as switchable. That difference indicates that some establishments had more than one

type of energy that could have been substituted for electricity usage during 1991.

The Heat Content of Energy Sources

Many of the estimates of individual energy sources in this report are presented in physical units (kilowatthours,

barrels, and short tons). Row totals and combinations of types of energy are presented in Btu. Tables A1 through

A5 are presented in physical units and Btu in Parts 1 and 2, respectively.

A Btu is the quantity of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. Thus,

converting physical units of a given type of energy to Btu is a means of expressing the heat content of that energy

source. All Btu quantities are in terms of higher heating value, with no regard for efficiency of use. Because no

energy consumption process is 100 percent efficient (although some are considerably more energy efficient than

others), Btu figures must be considered as the maximum available heat content. The following table presents the Btu

conversion factors of major types of energy.

454 Energy Information Administration/Manufacturing Consumption of Energy 1991
Table B2. Conversion of Physical Units to British Thermal Units

Type of Energy

British Thermal Units

(thousands)

Electric Energy (1,000 kilowatthours) ...............................................

Residual Fuel Oil (42 gallon barrel) ................................................

Distillate Fuel Oil (42 gallon barrel) ................................................

Natural Gas (1,000 cubic feet) ....................................................

Liquefied Petroleum Gas (42 gallon barrel) ...........................................

Coke and Breeze (short ton) .....................................................

Coal Used as Fuel (short ton) ....................................................

Coal Used for Coking (short ton) ..................................................

3,412

6,287

5,825

1,030

3,614

24,800

22,276

26,800

Source: Energy Information Administration, Monthly Energy Review (August 1992), pp. 147-151.

Revisions to 1988 MECS Estimates

An error was discovered after the 1988 MECS data were published. The nonenergy source shipments at petroleum

refineries (see "Feedstocks and Offsite-Produced Fuel at Petroleum Refineries" in this appendix) was miscalculated

and, as a result, overestimated. The following corrections should be made to the relevant 1988 MECS tables:

Table B3. Revisions to 1988 MECS Tables

(Estimates in Trillion Btu)

1988 MECS Publication Table 1 (Parts 1 and 2)

SIC

Code

As Published Revised

Industry Groups and Industry Total Other Total Other

Northeast

2911 Petroleum Refining ............ 583 W 546 W

29 Petroleum and Coal Products . . . . 598 523 560 485

Total ...................... 2,301 675 2,263 637

Midwest

2911 Petroleum Refining ............ 948 W 894 W

29 Petroleum and Coal Products . . . . 976 827 923 773

Total ...................... 4,778 1,011 4,724 958

South

2911 Petroleum Refining ............ 3,657 3,069 3,381 2,793

29 Petroleum and Coal Products .... 3,703 3,090 3,427 2,813

Total ...................... 10,839 4,622 10,563 4,345

West

2911 Petroleum Refining ............ 1,121 W 1,073 W

29 Petroleum and Coal Products .... 1,134 953 1,086 905

Total ...................... 2,616 1,373 2,568 1,325

United States

2911 Petroleum Refining ............ 6,310 5,364 5,893 4,947

29 Petroleum and Coal Products .... 6,411 5,393 5,995 4,976

Total ...................... 20,534 7,682 20,118 7,265

Energy Information Administration/Manufacturing Consumption of Energy 1991 455
Table B3. Revisions to 1988 MECS Tables (Continued)

1988 MECS Publication Table 2 (Parts 1 or 2)

SIC

Code

As Published Revised

Industry Groups and Industry Total Other Total Other

Northeast

2911 Petroleum Refining ............ 367 367 329 329

29 Petroleum and Coal Products . . . . 368 Q 330 Q

Total ...................... 699 W 661 W

Midwest

2911 Petroleum Refining ............ 482 482 429 429

29 Petroleum and Coal Products . . . . 486 Q 432 Q

Total ...................... 1,163 W 1,109 W

South

2911 Petroleum Refining ............ 2,005 2,005 1,729 1,729

29 Petroleum and Coal Products .... Q Q Q Q

Total ...................... 3,779 W 3,503 W

West

2911 Petroleum Refining ............ 403 403 355 355

29 Petroleum and Coal Products . . . . 410 W 361 W

Total ...................... 491 W 443 W

United States

2911 Petroleum Refining ............ 3,258 3,258 2,841 2,841

29 Petroleum and Coal Products .... 3,290 3,285 2,874 2,868

Total ...................... 6,132 3,531 5,716 3,114

1988 MECS Publication Table 7

(Primary Consumption by Economic Characteristic)

As Published Revised

Characteristic Total Other Total Other

Not Ascertained ..................... 3,258 3,258 2,841 2841

Total ............................. 20,534 7,682 20,118 7265

1988 MECS Publication Table 8

(Primary Consumption for Nonfuel Use by Economic Characteristic)

As Published Revised

Characteristic Total Other Total Other

Not Ascertained ..................... 3,258 3,258 2,841 2,841

Total ............................. 6,132 3,531 5,716 3,114

456 Energy Information Administration/Manufacturing Consumption of Energy 1991