EIA-EPA Energy-Related CO₂ Emissions Harmonization

Release date: September 25, 2025

Overview

The U.S. Energy Information Administration (EIA) and the U.S. Environmental Protection Agency (EPA) both publish estimates of energy-related carbon dioxide (CO₂) emissions. However, differences in the scope of emissions coverage, estimating methodologies, and definitions cause some of the emissions estimates to be misaligned between agencies.

This report was undertaken as part of the interagency response to Section 40419 of the Infrastructure Investment and Jobs Act (IIJA, 117th Congress of the United States 2021), which calls for the establishment of a system to harmonize estimates of greenhouse gases and other pollutant emissions published by EIA and EPA. The purpose of this report is to explain how and where these discrepancies exist, the extent of the discrepancies, and how users of EIA and EPA data can reconcile these differences. Although we aim to explain the differences, neither EIA nor EPA currently intends to change their respective emissions estimation methodologies as a result of the findings of this report.

This report focuses specifically on comparing estimates of annual U.S. energy-related fossil fuel combustion and non-energy use CO₂ emissions by economic sector. For EIA, the estimates for this comparison are from the July 2024 Monthly Energy Review (MER). For EPA, estimates are from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022 (GHGI). Understanding the purpose of each product provides valuable context into why emissions estimates differ between the two products.

The MER is EIA’s primary report of recent and historical U.S. energy statistics. In addition to estimates of CO₂ emissions, the MER also reports information on total energy production, consumption, stocks, trade, and energy prices; overviews of petroleum, natural gas, coal, electricity, nuclear energy, and renewable energy; and data unit conversions. The purpose of the MER is to provide Congress, federal and state agencies, energy analysts, and the general public with a comprehensive source of energy data and information.¹ In accordance with these objectives, the scope of CO₂ emissions estimates presented within the MER is limited to energy.

EIA considers energy-related CO₂ emissions to be those that occur from fossil fuel combustion and from the non-energy use (NEU, or also referred to as non-fuel or non-combustion use) of energy products. EIA’s NEU emissions predominantly consist of usage of energy products in industrial applications, such as petrochemical feedstocks.

The annual EPA GHGI report provides a comprehensive accounting of total greenhouse gas emissions from all man-made sources in the United States, including CO₂ removal from the atmosphere by sinks, going back to 1990. The gases covered by the GHGI include CO₂, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride. The GHGI groups greenhouse gas (GHG) emission and sink estimates into five inventory reporting sectors: Energy; Industrial Processes and Product Use (IPPU); Agriculture; Land Use, Land-Use Change, and Forestry (LULUCF); and Waste.

The emissions and removals presented in the GHGI report are organized by inventory reporting sector (as noted above) and within each sector calculated using internationally accepted methods for each source and sink category. The report presents estimates and underlying inputs using a common and consistent format that enables comparisons of emissions and/or removals of different GHG emissions across national inventories. As such, EPA’s definition of energy-related is largely informed by the 2006 United Nations Intergovernmental Panel on Climate Change reporting guidelines, which include fossil fuel combustion and fugitive emissions (intentional or unintentional release of GHG during the extraction, process, or delivery of fossil fuels). However, due to national circumstances associated with data collection, EPA deviates slightly from these guidelines by considering some NEU emissions to be energy-related as well.

This report only compares emissions estimates that are covered by both the EIA and EPA reports. Specifically, it covers CO₂ emissions from fossil fuel combustion (including the fossil component of municipal solid waste [MSW]) and CO₂ emissions associated with NEU. Geothermal energy-related CO₂ emissions are also included given their role in energy generation. Although not technically a fossil fuel, geothermal energy has associated non-condensable gases such as CO₂ in subterranean heated water.

Notes
¹In accordance with Section 205(a)(2) of the Department of Energy Organization Act.

²The 2006 IPCC guidelines suggest that all industrial process emissions, regardless of whether or not these emissions are associated with energy products, are reported under the IPPU chapter of a country’s emissions inventory.

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