Report: Power Plant Air Emissions Continue Steady Decline

In a report released this week, M.J. Bradley & Associates found that in 2013 power plant SO₂ emissions were 80% lower and NO_x emissions were down 74% compared to releases in 1990-the year Congress passed major amendments to the Clean Air Act.

The report, Benchmarking Air Emissions of the 100 Largest Electric Power Producers in the United States, was a collaborative effort among Bank of America, Calpine, Entergy, Exelon, Public Service Enterprise Group, Ceres, and the Natural Resources Defense Council. Publicly reported data was used to compare the emissions performance of the nation's 100 largest power producers. This is the eleventh such benchmarking report, which started in 1997.

Although CO₂ emissions in 2013 were actually up 14% from the amount recorded in 1990, compared to 2008 levels, CO₂ emissions have decreased 12%. Much of the recent reduction can be traced to energy efficiency improvements and the displacement of coal generation by natural gas and renewable resources. The Environmental Protection Agency (EPA) is expected to finalize its Clean Power Plan rule later this summer, which will regulate CO₂ emissions and force further reductions, if implemented as initially proposed.

Mercury is another air emission tracked in the report. It was down 50% in 2013 compared to levels in 2000, which is when mercury emissions began being reported by the industry. Additional reductions will be seen in future reports because the EPA's Mercury and Air Toxics Standards (MATS) went into effect this year. Although the Supreme Court remanded a case against MATS back to a lower court for further proceedings, many plants have already installed equipment to comply with the requirements or been permanently retired as a result of the rule, so future emissions will undoubtedly be lower.

The report also notes that U.S. power plant emissions are highly concentrated among a small number of producers. In 2013, the 100 largest power producers generated 87% of the industry's air pollution emissions. The top five companies in each of the emissions categories tracked by the report accounted for 25% or more of all industry emissions.

AEP led the proverbial way. It was the fifth largest producer in 2013, generating 153.1 million MWh of output, but its large coal-fired fleet of plants emitted more SO₂, NO_x, and mercury than any other company. AEP was also a close second in CO₂ emissions to Duke Energy-the nation's largest electricity generator with 243.4 million MWh produced in 2013. Exelon, with its nuclear-dominated fleet, had the lowest CO₂ emissions rate of the top 20 power producers.

Changes in the nation's fuel mix since 2000 were also striking. Generation from natural gas increased 87% and renewables contributed 51% more power, while the output from coal decreased 19% during the 14-year period. The figures corroborate findings from a report issued by the U.S. Government Accountability Office recently.

"Most parts of the country are firmly on the path toward a clean energy future, but some states and utilities have a longer way to go and overall the carbon emissions curve is still not bending fast enough," said Mindy Lubber, president of Ceres, a nonprofit sustainability advocacy group, which helped produce the report.

-Aaron Larson, associate editor (@AaronL_Power, @POWERmagazine)

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