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• 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"“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.

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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"“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 “modeled methane generation rate" 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" “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“back-calculated" 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.

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• 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 “Geologic Sequestration of Carbon Dioxide"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: http://www.epa.gov/ghgreporting/reporters/subpart/rr.html

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