Detailed Description of Data for Certain Sources and Processes

This page provides explanations specific data caveats associated with monitoring methods, as well as direct emitter and supplier subparts.

Monitoring Methods

Per 40 CFR Part 98, reporters (facilities and suppliers) were allowed to use Best Available Monitoring Methods (BAMM) for the first three months of 2010, rather than follow the monitoring methods in the reporting rule. Some reporters were allowed to use BAMM for an additional period of time in 2010. In using BAMM, reporters were required to follow the calculation procedures in the rule, but could use alternative means (e.g., engineering equations or company records) to determine the inputs to the emission equations.

Direct Emitters

Many facilities report carbon dioxide (CO2) emissions from processes at the facility and from stationary combustion. If a facility uses a Continuous Emissions Monitoring System (CEMS) to measure both the process emissions and the combustion emissions, then the combustion emissions are reported with the process emissions. For example, because process emissions from a cement kiln are emitted from the same stack as combustion emissions from the kiln, the combined process and combustion emissions are reported under cement production if a CEMS is used. If a CEMS is not used, process emissions are reported under cement production and combustion emissions are reported under stationary combustion.

Stationary Combustion (Subpart C)

  • Scope: Subpart C specifies the methods for calculating emissions from combustion equipment that is not covered by a calculation method specified in another subpart. Subpart C applies to facilities reporting under almost all industrial sectors, and the majority of facilities have combustion equipment reported under subpart C. Facilities reporting only under subpart C are from a variety of different industries.
  • Abbreviated Reporting: Certain facilities were eligible to submit an abbreviated GHG report for the 2010 reporting year. A facility could submit an abbreviated report if the only emissions being reported by the facility were stationary fuel combustion sources. Facilities that elected to submit abbreviated reports were required to submit only facility-level GHG emissions and not unit level information. Beginning with the 2011 reporting year, all facilities are required to submit full reports.
  • Equipment Groups (Configurations): Subpart C allows for facilities to report emissions from individual units as a combined group if certain criteria are met for all units in the grouping. The unit groupings are referred to as “configurations”, and there are several different options. The reporting requirements for subpart C vary depending on whether the unit is reported individually or as a group and whether the CO2 emissions for the group were calculated from fuel consumption or CEMS.

Electricity Generation (Subpart D)
The electricity generation source category applies to electricity generating units (EGUs) that are subject to the Acid Rain Program and units that are required by any other program to report CO2 mass emissions year-round according to 40 CFR part 75 (e.g., NOx Budget Program). EGUs that are not subject to subpart D must report CO2 emissions under subpart C (General Stationary Fuel Combustion Sources).

Stationary Combustion (Subpart C) and Electricity Generation (Subpart D)
Facilities must report separately biogenic CO2 emissions and CO2 emissions excluding biogenic CO2. However, for reporting year 2010 only, facilities with stationary combustion (subpart C) or electricity generation (subpart D) units that report CO2 emissions under 40 CFR part 75 were allowed to report combined biogenic and non-biogenic CO2 emissions for the part 75 units only.

Aluminum Production (Subpart F)
Perfluorocarbon (PFC) and CO2 emissions from on-site anode baking are reported under aluminum production. Carbon dioxide, nitrous oxide, and methane emissions from each stationary fuel combustion unit are reported by following the requirements of stationary combustion (subpart C) or electricity generation (subpart D), as applicable.

Ammonia Manufacturing (Subpart G)
Process emissions reported under the ammonia manufacturing subpart may include CO2 that is later consumed on-site for urea production. This CO2 is not released to the ambient air from the ammonia manufacturing process unit(s). Facilities that reported consuming some CO2 in this manner are marked with this icon in the publication tool.

Electronics Manufacturing (Subpart I)
Several facilities reported emissions of gases for which there are no listed global warming potentials (GWPs) under the Greenhouse Gas Reporting Program. The emissions of these gases are not included in the total emissions, expressed in metric tons of carbon dioxide equivalents (MTCO2e), for these facilities. The emissions of these gases are listed separately by gas in metric tons.

Fluorinated Gas Production (Subpart L)
Facilities reported the aggregate emissions from this process in metric tons of carbon dioxide equivalents (MTCO2e). They did not report emissions of individual greenhouse gases.

Hydrogen Production (Subpart P)
Process emissions reported under the hydrogen production subpart may include CO2 that is not released to the ambient air from the hydrogen manufacturing process unit(s). EPA cannot identify these facilities with an icon because it may disclose that the facility transferred non-CO2 carbon offsite, which was determined to be confidential business information (CBI).

Lime Manufacturing (Subpart S)
Process emissions reported under the lime manufacturing subpart may include CO2 that is later consumed on-site, along with manufactured lime, to produce other materials/products or for other industrial processes (e.g. sugar refining, etc.). This CO2 is not released to the ambient air from the lime manufacturing process unit(s). Facilities that reported consuming some CO2 in this manner are marked with this icon in the publication tool.

Petrochemical Production (Subpart X)
The petrochemical production reporting requirements specify that emissions due to the combustion of ethylene process off-gas calculated using the alternative combustion methodology for ethylene production processes, as specified in §98.243(d), must be reported as process emissions under petrochemical production. In the reporting tool, however, these emissions are instead included in the combustion emissions (Subpart C) for the facility.

Petroleum Refineries (Subpart Y)
Emissions from non-merchant hydrogen plants at refineries (i.e., hydrogen plants that are owned or under the direct control of the refinery owner and operator) are reported under hydrogen production (Subpart P) and displayed as “hydrogen”.

Municipal Solid Waste Landfills (Subpart HH)
Municipal Solid Waste Landfills with active landfill gas collection systems must calculate and report GHG emissions in two ways: using Equation HH-6 and Equation HH-8. The tool displays emissions from both equations. These two results should not be added together to arrive at an emissions total. Only one of these numbers (in most cases the larger value) was used as the emissions from the landfill. This value was added to any other emissions sources at the facility, such as stationary combustion, to arrive at the emissions total for the facility. The two emission estimation methods are explained below.

  • Equation HH-6 estimates emissions from a modeled methane generation rate and other factors. This “modeled methane generation rate” is predicted based on the quantity and types of waste historically disposed in the landfill using the first order decay model (see 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 5). Methane generation is then corrected for the measured amount of methane recovered and destroyed. Methane generated in excess of the measured methane recovery is corrected for methane oxidation near the soil surface. If the measured quantity of methane recovered is greater than the modeled methane generation rate, then the quantity of methane recovered is used as the modeled methane generation rate to avoid “negative emissions” as a result of this equation.
  • Equation HH-8 estimates emissions based on the measured quantity of methane that was recovered for destruction and an estimated landfill gas collection efficiency. This “back-calculated” quantity of the uncollected gas is then corrected for methane oxidation near the soil surface. Emissions from the quantity of methane recovered for destruction are estimated based on the destruction efficiency.

Facilities that Report under Subpart PP (Suppliers of Carbon Dioxide) and under Subpart AA (Pulp and Paper), Subpart G (Ammonia Production) or Subpart P (Hydrogen Production)
Some facilities reporting under the pulp and paper, ammonia and hydrogen subparts also report under Subpart PP (Suppliers of CO2). Subpart PP includes facilities that have production process units that collect a CO2 stream for purposes of transferring CO2 offsite to supply commercial applications or collect and maintain custody of a CO2 stream in order to sequester or otherwise inject it underground. In certain cases, CO2 reported under Subpart PP may be included in the annual emissions total reported under Subpart AA, G or P for those facilities. Facilities are marked with this icon in the publication tool if they reported under (1) Subpart PP and (2) Subpart AA, G or P.

Electrical Equipment Manufacture or Refurbishment (Subpart SS)
Only facilities that with total annual sulfur hexafluoride (SF6) and perfluorocarbon (PFC) purchases greater than 23,000 pounds report under the Greenhouse Gas Reporting Program. Emissions include those at the manufacturing facility as well as any emissions from the equipment installation process at an off-site electric power transmission or distribution location that occur before title to the equipment is transferred to the transmission or distribution entity. Emissions from equipment after title is transferred are reported under Electrical Transmission and Distribution Equipment Use (Subpart DD).


Suppliers are those entities that supply products into the economy which if combusted, released or oxidized emit greenhouse gases into the atmosphere. These fuels and industrial gases are not emitted from the supplier facility but instead distributed throughout the country and used. An example of this is gasoline, which is sold in the U.S. and primarily burned in cars throughout the country. The majority of GHG emissions associated with the transportation, residential and commercial sectors are accounted for by these suppliers.

Suppliers of Natural Gas and Natural Gas Liquids (Subpart NN)

  • Local distribution companies (LDCs) report the CO2 emissions that would result from the complete combustion or oxidation of the annual supply of natural gas delivered to end-users, reported as follows: (1) Each meter registering supply of 460,000 thousand standard cubic feet (Mscf) or more during the calendar year, and (2) the sum of all meters registering less than 460,000 Mscf during the calendar year. The total GHG quantity displayed for each LDC in this data set is the sum of these values, reflecting the emissions associated with all natural gas delivered by the LDC during 2010.
  • LDCs report the GHG quantity associated with all natural gas deliveries, both gas owned by the LDC and gas not owned by the LDC. Quantities of gas delivered displayed in this data set may differ from data reported to the Energy Information Administration (EIA) because EIA requires separate reporting of these quantities.

Injection of Carbon Dioxide

  • Injection of Carbon Dioxide (Subpart UU)
    Certain facilities reporting under subpart UU have been granted Research and development (R&D) project exemptions from reporting requirements under 40 CFR part 98, subpart RR “Geologic Sequestration of Carbon Dioxide”. A project is eligible for the exemption if it investigates practices, monitoring techniques, or injection verification, or if it is engaged in other applied research that focuses on enabling safe and effective long-term containment of a CO2 stream in subsurface geologic formations, including research and injection tests conducted as a precursor to a larger more permanent long-term storage operation. Facilities that report CO2 received under Subpart UU and hold an R&D project exemption from subpart RR are marked with this icon insert icon in the publication tool. For more information on facilities that have received an R&D project exemption, see:

#Back to Top

This web site is maintained by a contractor to the U.S. Environmental Protection Agency (RY2023.R.01)