The largest electric producers in the US continue to reduce emissions of key air pollutants, according to an annual analysis of power plant emissions.
The new report analyzed publicly reported data on carbon dioxide, nitrogen oxides (NOx), sulfur dioxide (SO2), and mercury emissions from the nation’s 100 largest electric power producers, including Duke, Southern, NextEra Energy, Exelon and AEP. These 100 biggest companies account for 85 percent of the nation’s power production.
Benchmarking Air Emissions of the 100 Largest Electric Power Producers in the United States concludes that since 2000 emissions of all four major pollutants have dropped while total electricity generation and the American economy have grown. This echoes last year’s benchmarking report.
CO2 emissions totaled 1.96 billion tons in 2014. But they dropped 15 percent between 2005 and 2014, and with preliminary data suggesting another 6 percent decline in 2015, CO2 emissions are almost back down to 1990 levels, the report says.
Despite the overall declines, there is still significant variability among power producers, with some power providers achieving fleet-wide CO2 emissions rates that are 10 times lower than others. Duke, the largest electric power producer in the US, for example, has a CO2 emission rate (determined by dividing emissions by electricity produced) of 1,129 compared to Exelon, the fourth largest producer, with a CO2 emission rate of 80. And no. 93, Big Rivers Electric, has a CO2 emission rate of 2,294.
The report says three primary factors are driving the drop in CO2 emissions: energy efficiency improvements, coal plant retirements driven by market conditions and new air pollution standards, and an increase in generation from low- and zero-emitting resources, including natural gas, wind and solar.
Installed wind and solar capacity in the US has more than doubled in the past five years to over 100 gigawatts. Their combined output is now comparable to total hydroelectric generation in the US. Nuclear power continues to be the largest source of zero-carbon generation in the country at 62 percent of total non-emitting output.
The report also ranks states by the amount of each pollutant released. The 10 states with the highest CO2 pollution are: Texas, 263.3 million tons; Florida, 119 million tons; Indiana, 114.1 million tons; Pennsylvania, 109.3 million tons; Ohio, 106 million tons; Illinois, 101 million tons; Kentucky, 94.1 million tons; Missouri, 82.8 million tons; West Virginia, 79.5 million tons; and Alabama, 73.4 million tons.
When ranked by CO2 emissions rate, the top 10 states in descending order are Kentucky, Wyoming, West Virginia, Indiana and Missouri, North Dakota, Utah, New Mexico, Ohio, and Colorado.
Other key findings include:
In 2014, power plant SO2 and NOx emissions were 80 percent and 75 percent lower, respectively, than in 1990, when Congress passed major amendments to the Clean Air Act.
Mercury air emissions from power plants have decreased 55 percent since 2000. Mercury emissions will 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 2014, power plants were responsible for 62 percent of SO2 emissions, 14 percent of NOx emissions, 58 percent of mercury air emissions (among sources reporting to EPA’s Toxic Release Inventory), and 37 percent of all CO2 emissions in the US.
Air pollution is highly concentrated among just a few electricity producers: Ten producers were responsible for 56 percent of SO2 emissions; 43 percent of NOx; 49 percent of mercury; and 40 percent of CO2 emissions.
Coal accounted for 40 percent of the power produced by the top 100 power producers, followed by natural gas at 26 percent, nuclear at 22 percent, and renewable power, including large hydroelectric, and other sources at 12 percent.
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