Electric Power Sector Emissions

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Greenhouse Gas Emissions in the Electric Power Sector by Fuel Source
Electric Power Sector Trends
Greenhouse Gas Emissions by Electricity End Use
Reducing Emissions from Electric Power Production

Greenhouse Gas Emissions in the Electric Power Sector by Fuel Source

The electricity power sector involves the generation, transmission, and distribution of electricity. Carbon dioxide (CO₂) makes up the vast majority of greenhouse gas emissions from the sector, but smaller amounts of methane (CH₄) and nitrous oxide (N₂O) are also emitted. These gases are released during the combustion of fossil fuels, such as coal, oil, and natural gas, to produce electricity. Less than 1% of greenhouse gas emissions from the sector come from sulfur hexafluoride (SF₆), an insulating chemical used in electricity transmission and distribution equipment.

Coal combustion is more carbon-intensive than burning natural gas or petroleum for electric power production. Although coal use accounted for 55% of CO₂ emissions from the sector, it represented only 20% of the electricity generated in the United States in 2022.
Natural gas use accounted for 39% of electricity generation in 2022, and petroleum use accounted for less than 1%.
The remaining generation in 2022 came from non-fossil fuel sources, including nuclear (19%) and renewable energy sources (21%), which include hydroelectricity, biomass, wind, and solar.¹ Most of these non-fossil sources, such as nuclear, hydroelectric, wind, and solar, are non-emitting.

Electric Power Sector Trends

In 2022, the electric power sector was the second largest source of U.S. greenhouse gas emissions, accounting for 25% of the U.S. total.
Electric power sector emissions increased 7% in 2021.
Greenhouse gas emissions from electric power production have decreased by about 15% since 1990 due to a shift in generation to lower- and non-emitting sources of electricity generation and an increase in end-use energy efficiency.

Greenhouse Gas Emissions by Electricity End-Use

Electricity is used by other end-use sectors—in homes, businesses, and factories—and the greenhouse gas emissions from electricity generation can be allocated to the sectors that use the electricity. Looking at greenhouse gas emissions by end-use sector can help us understand energy demand across sectors and changes in energy use over time.

When emissions from electric power generation are allocated to the industrial end-use sector, industrial activities account for a much larger share of U.S. greenhouse gas emissions.
Greenhouse gas emissions from commercial and residential buildings also increase substantially when emissions from electricity end-use are included, due to the relatively large share of electricity use mostly building related (e.g., heating, ventilation, and air conditioning; lighting; and appliances) in these sectors.
The transportation sector currently has a relatively low percentage of electricity use and thus indirect emissions, but it is growing due to the use of electric and plug-in vehicles.

Reducing Emissions from Electric Power Production

There are a variety of opportunities to reduce greenhouse gas emissions associated with electric power production, transmission, and distribution. The table below categorizes these opportunities and provides examples. For a more comprehensive list, see Chapter 6 (pdf) of the Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.²

Examples of Reduction Opportunities in the Electric Power Sector
Type	How Emissions Are Reduced	Examples
Increased Efficiency of Fossil-fired Power Plants and Fuel Switching	Increasing the efficiency of existing fossil fuel-fired power plants by using advanced technologies, substituting less carbon-intensive fuels, and shifting generation from higher-emitting to lower-emitting power plants.	Converting a coal-fired boiler to use of natural gas, or co-firing natural gas. Converting a single-cycle gas turbine into a combined-cycle turbine. Shifting dispatch of electric generators to lower-emitting units or power plants.
Renewable Energy	Using renewable energy sources rather than fossil fuel to generate electricity.	Increasing the share of total electricity generated from wind, solar, hydro, and geothermal sources, as well as certain biofuel sources, through the addition of new renewable energy generating capacity.
Increased End-Use Energy Efficiency	Reducing electricity use and peak demand by increasing energy efficiency and conservation in homes, businesses, and industry.	EPA's ENERGY STAR® partners avoided over 400 million metric tons of greenhouse gases in 2020 alone, helped Americans save over $42 billion in energy costs, and reduced electricity use by 520 billion kWh.
Nuclear Energy	Generating electricity from nuclear energy rather than the combustion of fossil fuels.	Extending the life of existing nuclear plants and building new nuclear generating capacity.
Carbon Capture and Sequestration (CCS)	Capturing CO₂ as a byproduct of fossil fuel combustion before it enters the atmosphere, transporting the CO₂, injecting the CO₂ deep underground at a carefully selected and suitable subsurface geologic formation where it is securely stored. Learn more about CCS.	Capturing CO₂ from the stack of a coal-fired power plant and then transferring the CO₂ via pipeline, injecting the CO₂ deep underground at a carefully selected and suitable nearby abandoned oil field where it is securely stored.

References

U.S. Energy Information Administration (2022). Electricity Explained - Basics.
IPCC, 2022: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [P.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926

Explanation of Units

A million metric tons of CO₂: What does that mean?

A million metric tons equals about 2.2 billion pounds, or 1 trillion grams. For comparison, a small car is likely to weigh a little more than 1 metric ton. Thus, a million metric tons are roughly the same mass as 1 million small cars.

The U.S. GHG Inventory uses metric units for consistency and comparability with other countries. For reference, a metric ton is slightly more (approximately 10%) than a U.S. "short" ton.

Greenhouse gas emissions are often measured in carbon dioxide (CO₂) equivalent. To convert emissions of a gas into CO₂ equivalent, its emissions are multiplied by the gas's Global Warming Potential (GWP). The GWP takes into account the fact that many gases are more effective at warming Earth than CO₂, per unit mass.

The GWP values appearing in the Overview of Greenhouse Gases and Sources of Greenhouse Gas web pages reflect the values used in the U.S. GHG Inventory, which are drawn from the IPCC's Fifth Assessment Report (AR5). For further discussion of GWPs and an estimate of greenhouse gas emissions using updated GWPs, see Annex 6 of the U.S. GHG Inventory and the IPCC's discussion on GWPs (PDF) (106 pp, 7.7MB).