Power Plant Emissions Down Substantially in U.S. Since 1990

Power plant SO2 and NOx emissions have decreased 92% and 84%, respectively, since Congress passed major amendments to the Clean Air Act in 1990. Meanwhile, mercury air emissions from power plants have decreased 90% since 2000, as federal limits on mercury and other hazardous air pollutants from coal-fired power plants went into effect in 2015.

The revelations are just a few of the findings from a report titled Benchmarking Air Emissions of the 100 Largest Electric Power Producers in the United States, which was authored by M.J. Bradley & Associates and released this week. The benchmarking analysis is a collaborative effort among Ceres; Bank of America; power producers Entergy and Exelon; and the Natural Resources Defense Council (NRDC). The latest analysis is the 15th such report released since 1997.

“As harmful emissions from the U.S. power sector continue to decline, it’s clear that policy solutions, market forces, company leadership, and stakeholder engagement are successfully driving the clean energy transition,” Starla Yeh, director of the Policy Analysis Group of the Climate and Clean Energy program at NRDC, said in a news release accompanying the report.

Notably, there was one recent exception to the downward trend in emissions. Power sector releases of CO2 increased 1% between 2017 and 2018. “The sector must ensure it recovers the ground it lost in 2018 with consistent and steep reductions in climate and air pollution over the coming decades in order to do its part in meeting domestic and global decarbonization goals,” Yeh added. Still, CO2 emissions have decreased 25% since peaking in 2007, even as U.S. gross domestic product—a measure of the total value of goods produced and services provided in the country—grew more than 35% over the same period.

The report says electricity accounted for almost 40% of primary energy use in the U.S. in 2018, and its share of energy supply is expected to increase in the coming decades with the electrification of transportation and other end-uses.

“As the benchmark analysis continues to make clear, we must increase corporate ambition and find solutions to transform the power sector at a scope and scale that matches the climate crisis,” said Dan Bakal, senior director of electric power at Ceres—a nonprofit organization focused on sustainability.

Interestingly, there is wide variability in carbon emission rates among U.S. power producers. Five of the 20 largest generators emit more than 1,500 lb of CO2/MWh while five others emit less than 650 lb of CO2/MWh. With its large nuclear fleet, Exelon emitted the least—107 lb of CO2/MWh (less than a quarter the amount of any other producer)—while, of the top 20 producers, Ameren was at the high end, emitting 1,696 lb of CO2/MWh.

“As the largest producer of zero-carbon energy in the United States, Exelon stands with the overwhelming majority of our customers who want cleaner air and affordable, reliable energy,” said Exelon Senior Vice President, Corporate Strategy and Chief Innovation and Sustainability Officer Chris Gould. “The valuable insights and analysis from this report will help us continue to drive the deep decarbonization necessary to address the climate crisis facing our customers and communities.”

Aaron Larson is POWER’s executive editor (@AaronL_Power, @POWERmagazine).