New Report: U.S. Power Sector Emissions Decline as the Generation Mix Continues to Evolve

BOSTON, MA  – The nation’s largest electricity producers continue to substantially reduce emissions of key air pollutants, the latest comprehensive analysis of U.S. power plant emissions shows.

The new report analyzed publicly reported data on carbon dioxide (CO2), nitrogen oxides (NOx), sulfur dioxide (SO2), and mercury emissions from the nation’s 100 largest electric power producers, which account for 85 percent of the nation’s power production and 86 percent of the industry’s air emissions.  The company rankings are based on 2015 data; however, the report also includes industry-wide trends through 2016.

Notably, the report, “Benchmarking Air Emissions of the 100 Largest Electric Power Producers in the United States,” concludes that since 2000 emissions of several key pollutants have dropped significantly even as the American economy has grown.

“After a slow down in the pace of improvement, it was encouraging to see the industry continue to drive down its air pollution emissions in 2015 and 2016,” said Dan Bakal, director of electric power at the sustainability nonprofit organization Ceres. “Many companies have increased their investments in clean energy and pollution control projects, and are demonstrating that emission reductions and economic growth can go hand in hand.”

The report, which ranks emissions by power producer and state, finds that electric sector CO2 emissions—a key driver of climate change—were 2.12 billion tons in 2015.  CO2 emissions have declined 20 percent between 2005 and 2015, and preliminary data suggest another 5 percent decline in 2016, which would reduce the sector’s emissions to 1990 levels.  Additionally, for the first time since publication of the Benchmarking report, SO2 and NOx emissions from the electric sector were each below 2 million tons in 2016.  Despite the overall declines, there is still significant variability among power producers.  For example, among the Top 100 power producers, CO2 emission rates range from 0 to 2,245 pounds per megawatt hour; companies with significant non-emitting generation (e.g., nuclear and renewables) generally have the lowest CO2 emission rates.

“The emissions trends in the benchmarking report demonstrate the critical importance of the Clean Air Act in protecting human health and the environment,” said Kevin Steinberger, policy analyst in the Climate and Clean Air Program at the Natural Resources Defense Council. “The electric industry has made a strong pivot to clean energy, with record additions of renewable energy in recent years, and we don’t see that trend abating.”

Other key findings in the benchmarking report include:

  • In 2015, power plant SO2 and NOx emissions were 87 percent and 79 percent lower, respectively, than in 1990, when the U.S. Congress last passed major amendments to the Clean Air Act.
  • In 2015, mercury air emissions from power plants were 69 percent lower than in 2000.  Mercury emissions should continue to decline as the first federal limits on mercury and other hazardous pollutants from coal-fired power plants went into effect in 2015 and 2016.
  • In 2015, power plants were responsible for 59 percent of SO2 emissions, 13 percent of NOx emissions, 44 percent of mercury air emissions (in 2014, the most recent for which all-source mercury data is available), and 38 percent of all CO2 emissions in the U.S.
  • Emissions from power plants are highly concentrated among just a few electricity producers: Ten producers were responsible for 52 percent of SO2 emissions; 40 percent of NOx; 47 percent of mercury; and 38 percent of CO2 emissions.   
  •  Coal accounted for 34 percent of the power produced by the top 100 power producers, followed by natural gas at 32 percent, nuclear at 23 percent, and renewable power, including large hydroelectric, and other sources at 12 percent. For the first time, in 2015, coal and natural gas generation from all U.S. power plants was virtually equal.

“The benchmarking report is an important resource for tracking changes in the environmental performance of the U.S. electric power sector and making this information available to our stakeholders – owners, customers, employees and communities,” said Chuck Barlow, vice president of environmental strategy and policy for Entergy Corporation. “The collection and reporting of these data by EPA and EIA serves a critical function in allowing us to benchmark our performance against our peers in the industry and track the industry’s overall environmental progress.”

The benchmarking report is the 13th in a series since 1997 highlighting environmental improvements and progress in the nation’s electric sector.  The report ranks each power company’s emissions and its emission rate (determined by dividing emissions by electricity produced) for each pollutant against the emissions and rates of the other companies.

In addition, states are ranked by the amount of each pollutant released. For example, the 10 states with the highest CO2 emissions are: Texas, 248.2 million tons; Florida, 116.1 million tons; Pennsylvania, 96.4 million tons; Indiana, 95.7 million tons; Ohio, 89.3 million tons; Illinois, 88.6 million tons; Kentucky 81.1 million tons; Missouri, 70.5 million tons; West Virginia, 71.0 million tons; and Michigan, 70.6 million tons.

When ranked by CO2 emissions rate (lb CO2/MWh), the top 10 highest-emitting states in descending order are Wyoming, Kentucky, West Virginia, Indiana, North Dakota, Utah, Missouri, New Mexico, Colorado, and Ohio.

Based on 2015 generation and emissions data from the U.S. Energy Information Administration (EIA) and EPA, the benchmarking report is a collaborative effort between Ceres; Bank of America; power producers including Calpine, Entergy, Exelon, and Tenaska; and the Natural Resources Defense Council. It is authored by M.J. Bradley & Associates. 


About NRDC
The Natural Resources Defense Council (NRDC) is an international nonprofit environmental organization with more than 2 million members and online activists. Since 1970, our lawyers, scientists, and other environmental specialists have worked to protect the world's natural resources, public health, and the environment. NRDC has offices in New York City, Washington, D.C., Los Angeles, San Francisco, Chicago, Livingston, Montana, and Beijing. Visit us at and follow us on Twitter @NRDC.

About Ceres
Ceres is a sustainability nonprofit organization working with the most influential investors and companies to build leadership and drive solutions throughout the economy. Through powerful networks and advocacy, Ceres tackles the world’s biggest sustainability challenges, including climate change, water scarcity and pollution, and human rights abuses. For more information, visit and follow @CeresNews.

About Calpine
Calpine Corporation is America’s largest generator of electricity from natural gas and geothermal resources with operations in competitive power markets. Our fleet of 80 power plants in operation or under construction represents approximately 26,000 megawatts of generation capacity. Through wholesale power operations and our retail businesses Calpine Energy Solutions and Champion Energy, we serve customers in 25 states, Canada and Mexico. Our clean, efficient, modern and flexible fleet uses advanced technologies to generate power in a low-carbon and environmentally responsible manner. We are uniquely positioned to benefit from the secular trends affecting our industry, including the abundant and affordable supply of clean natural gas, environmental regulation, aging power generation infrastructure and the increasing need for dispatchable power plants to successfully integrate intermittent renewables into the grid. Please visit to learn more about how Calpine is creating power for a sustainable future.

About Entergy Corporation
Entergy Corporation is an integrated energy company engaged primarily in electric power production and retail distribution operations. Entergy owns and operates power plants with approximately 30,000 megawatts of electric generating capacity, including nearly 9,000 megawatts of nuclear power. Entergy delivers electricity to 2.9 million utility customers in Arkansas, Louisiana, Mississippi and Texas. Entergy has annual revenues of approximately $10.8 billion and nearly 13,000 employees.

About Exelon
Exelon Corporation (NYSE: EXC) is a Fortune 100 energy company with the largest number of utility customers in the U.S. Exelon does business in 48 states, the District of Columbia and Canada and had 2016 revenue of $31.4 billion. Exelon’s six utilities deliver electricity and natural gas to approximately 10 million customers in Delaware, the District of Columbia, Illinois, Maryland, New Jersey and Pennsylvania through its Atlantic City Electric, BGE, ComEd, Delmarva Power, PECO and Pepco subsidiaries. Exelon is one of the largest competitive U.S. power generators, with more than 33,300 megawatts of nuclear, gas, wind, solar and hydroelectric generating capacity comprising one of the nation’s cleanest and lowest-cost power generation fleets. The company’s Constellation business unit provides energy products and services to approximately 2.2 million residential, public sector and business customers, including more than two-thirds of the Fortune 100. Follow Exelon on Twitter @Exelon.

About Tenaska
Tenaska, based in Omaha, Nebraska, is one of the leading independent power producers in the United States, with regional offices in Dallas, Denver, Pittsburgh, Philadelphia, Boston and Calgary, Alberta and Vancouver, British Columbia, Canada. Forbes magazine ranks Tenaska among the largest privately held U.S. companies. Tenaska and its affiliates have developed approximately 10,000 megawatts (MW) of natural gas-fueled and renewable power generation and manage operations for approximately 7,000 MW of power generation consisting of nine power plants.  Tenaska affiliates also market natural gas and electric power and provide energy risk management services. Tenaska is involved in asset acquisition, natural gas fuel supply and transportation systems, and electric transmission development. For more information about Tenaska, visit

About Bank of America
At Bank of America, our focus on environmental, social and governance (ESG) factors is critical to fulfilling our purpose of helping make people’s financial lives better. Our commitment to growing our business responsibly is embedded in every aspect of our company. It is demonstrated in the inclusive and supportive workplace we create for our employees, the responsible products and services we offer our customers, and the impact we make around the world in helping local economies thrive. An important part of this work is forming strong partnerships with nonprofits and advocate groups, such as community and environmental organizations, in order to bring together our collective networks and expertise to achieve greater impact. Learn more at, and connect with us on Twitter at @BofA_News.

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