Manufacturing Energy Consumption Survey

Calculation of MECS Energy Measures

Reported energy values were used to construct several derived values, which, in turn, were used to prepare the estimates appearing in MECS consumption tables--First Use, Total Inputs, Offsite-Produced. These derived values are displayed in Table 1 and 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.



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, 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, is excluded 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.



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 continued from 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 and no adjustment were made, the total Btu quantity among the producing and receiving establishments would be duplicative and thus overstated. Deducting this derived value from the producing establishments' energy consumption avoids the duplication.

The first four of those derived values represent an addition to the energy consumed onsite; that is, either energy was produced offsite or was produced onsite from nonenergy inputs. These four values are described in the 1994 MECS publication as first use (formerly primary consumption).

The fifth derived value described above does not represent an addition because this value represents energy that 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.

Table 1. Calculating Energy Measures, 1994

First Use (formerly Primary Consumption) of Energy for All Purposes

In previous reports, the term primary consumption was unclear and misunderstood by some data users. Instead of interpreting primary as the first use of energy at the manufacturing site (as it was intended), some readers interpreted primary as accounting for energy losses in generating and transmitting electricity. To avoid future misunderstandings, the term primary has been renamed first use in this report, and for all subsequent reports. This measure is intended to represent total demand for energy by manufacturers. These estimates, except for those of energy uses by petroleum refineries, are based on the following derived values:

• 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
• Energy produced onsite from energy inputs and shipped to other establishments.

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 intra-establishment double-counting.

The estimates shown in the petroleum refinery row of first-use tables are conceptually different from the estimates in the other rows of that table. For all industries except petroleum refineries, each cell represents the total first use 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 a 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 first use of energy.

First Use (formerly Primary Consumption) of 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. These tables present the nonfuel first use of energy. 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.

These estimates, except for those of energy use by petroleum refineries, 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.

Total Inputs of Energy for Heat, Power, and Electricity Generation

These tables 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." That reported value is exactly equal to the sum of the following derived values:

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

Thus, the estimates of combustible energy for these tables 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 these examples, it is clear that the input energy was not consumed as a fuel and would not have been included elsewhere in these tables.

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 the table.

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 these tables is the same net electricity estimate that appeared in the table of first use of energy for all purposes. 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 the Total Inputs tables is consistent with a concept of first use of energy for heat, power, and electricity generation.

Contact:

mschippe@eia.doe.gov

Mark Schipper

Phone: (202) 586-1136

Fax: (202) 586-0018