A report that examines and compares sulfur dioxide (SO2), nitrogen oxides (NOx), mercury, and carbon dioxide (CO2) emissions of the 100 largest power producers in the U.S. based on 2010 generation numbers says those companies produced 88% of the nation’s total power plant emissions of those pollutants.  

The companies examined in the report, “Benchmarking Air Emissions of the 100 Largest Power Producers in the U.S.,” include private and public entities that own about 2,500 power plants and accounted for 86% of the nation’s reported generation in 2010 (97% of all nuclear power, 90% of all coal-fired power, 82% of all hydroelectric power, 78% of all natural gas-fired power, and 62% of all non-hydroelectric renewable power). These companies also accounted for 88% of the industry’s reported emissions of the four air pollutants, it says. 

The report suggests that the nation’s power plant emissions of SO2 and NOx took a dramatic plunge of 68% in 2010, compared to 1990 levels, and emissions continue to decline. CO2 emissions were 24% higher than they were in 1990, however, spurting 5% over 2009 and 2010 due to increased energy consumption across all sectors. No long-term emissions trends are available for mercury, because "power plants have only recently begun to report their mercury emissions," it says. 

Report: AEP, Southern Lead List of Heaviest Emitters

Of the nation’s 100 largest power companies, American Electric Power (AEP), the nation’s second-largest generator, reportedly had the highest emissions (measured in tons) of SO2, NOx, and CO2, and the second-highest emissions of mercury. The largest generator, Southern Co., had the second-largest emissions of SO2, NOx, and CO2, and the third-largest emissions of mercury, according to the report. Energy Future Holdings, Dallas-based Luminant’s parent company and the company that ranked 18th in the generation size, reportedly had the highest emissions of mercury. 

Buckeye Power, an Ohio-based electricity generating and transmission cooperative that is owned by 25 distribution cooperatives, had the highest average SO2 emission rate (measured in pounds/MWh) for all its generating sources, even though it ranked 85th in the size of its generation fleet. Chicago-based Integrys (which ranked 75th in size) had the highest average NOx emission rate, and Kentucky-based Big Rivers Electric cooperative (ranking 82nd in size) had the highest average CO2 emissions rate. 

"The benefit of using emissions rates is that it creates a way of comparing power producers’ emissions when there is a large discrepancy between their overall annual generation (MWh)," Ceres spokesperson Brian Bowen told POWERnews.

A Period of Transition

According to the report, the electric power sector is "in a period of transition." The dramatic fall of natural gas prices since 2008 has led companies to "rethink" investment choices, specifically, whether to invest in upgrading older fossil-fired power plants or retire them over the next decade. The dilemma is compounded by new environmental rules and by the widespread adoption of renewables, distributed generation, and smart grid technologies, it notes. 

To illustrate how generators are increasingly using natural gas to produce power, the report points to an Energy Information Administration finding that natural gas generation was virtually equal to coal generation in April 2012, each fuel providing 32% of the nation’s total generation. "Southern Company, for example, historically one of the nation’s largest users of coal, expects to consume more natural gas than coal in 2012 for the first time in its 100-year history," it says. 

It also points out that 40 GW of coal plant retirements have been announced since January 2010, scheduled to occur between now and 2020. More than half of all announced retirements will occur in Ohio, Virginia, West Virginia, Pennsylvania, and Indiana, and they are concentrated among a "small number of companies": AEP, GenOn, Duke Energy, Tennessee Valley Authority (TVA), and Dominion, for example, account for about 60% of announced retirements. 

Meanwhile, renewable generation doubled from 83 million MWh to 195 million MWh (or about 5% of U.S. generation) between 2004 and 2011, while utility efficiency budgets increased 26% to $6.8 billion in 2011 and power market operators are encouraging an expanded role for energy efficiency, the report says. The renewable sector is facing uncertainties with the federal production tax credit (PTC) for wind energy set to expire at the end of the year. Though some states have implemented incentives, including a green bank and feed-in tariffs, several state governors are also expressing interest in reducing or eliminating renewable portfolio standards while they grapple with interconnection limits and the technical challenges of integrating variable renewables.

The report was sponsored by an industry think tank, the Ceres Coalition; power companies Entergy, Exelon, and Tenaska; nonprofit environmental legal group the Natural Resources Defense Council; and the Bank of America. Staff from environmental consulting group M.J. Bradley & Associates authored the report. 

Sources: POWERnews, Ceres