Tamar Hallerman
GHG Monitor
05/25/12
Decades-old fossil fuel-fired electricity generation produces a “disproportionate” share of carbon dioxide, sulfur dioxide and nitrogen oxide emissions in the power sector compared to newer units, a new Government Accountability Office report concludes. Commissioned by the Senate Environment and Public Works Committee, the GAO report released late last week finds that older electric generating units that began operating before 1978—93 percent of which are coal-fired—provided nearly half of the country’s electricity from fossil fuel-fired units in 2010 but also produced a “disproportionate share” of CO2, SO2 and NOx emissions. “Specifically, older units generated 45 percent of the electricity from fossil fuel units in 2010 but emitted 75 percent of sulfur dioxide emissions, 64 percent of nitrogen oxide emissions and 54 percent of carbon dioxide emissions,” the report says.
GAO examined the country’s 1,485 fossil fuel-fired units built before 1978 and the 1,958 units brought online after that date and compared fuel type, location, energy production and emissions. The report found that two-thirds of the coal generation that was operating in 2010 had been online for more than 30 years. The study also determined that more than three-quarters of natural gas-fired generation—which totaled roughly a quarter of power generation in 2010—has been built since 2000. That disparity of a majority of older fossil units being coal and newer units burning gas is one of the reasons why the emissions rates are so much larger for older plants as a whole, according to GAO. The agency calculated that for each unit of electricity generated in 2010, older units emitted more than three-and-a-half times more SO2, more than two times the NOx and 1.3 times the CO2 as newer units. “The difference in emissions between older and newer units is likely due, in part, to significant changes in the fuels used to generate electricity—in particular, a shift from coal to natural gas. Compared with coal, natural gas produces substantially lower emissions per unit of electricity generated, largely because natural gas contains less sulfur and carbon,” the report concludes.
In addition to the relatively dirtier nature of coal-fired generation compared to gas, the emissions disparity can also be attributed to the fact that fewer older plants have installed emissions controls than newer plants. The Environmental Protection Agency’s New Source Review rule that requires the operators of new and significantly-modified electric generating units to obtain preconstruction permits, adhere to emissions limits and use state-of-the-art pollution control technologies did not kick in until late 1977, GAO said, and exempted units built before that point. Finally, GAO concludes that the emissions disparity between old and new fossil units can be attributable to the fact that the former is generally less efficient than the latter.
EPA Regulations Could Shift Stats
While older coal-fired units play a significant role in providing the vast majority of electricity generation to regions of the country such as the Midwest and Southeast, much that reliance will likely shift in the coming years as older units retire and utilities move towards natural gas due to its cheaper price. EPA’s recently-finalized Mercury and Air Toxics Standards (MATS) and Cross-State Air Pollution Rule (CSAPR), which require emissions reductions in mercury and toxic air pollutants and SO2, NOx and fine particulates, respectively, will also likely lead to a significant shift to gas as many utilities decide that it is more economical to build new gas capacity than it is to retrofit aging coal units with state-of-the-art pollution control technology (see related story). However, those rulemakings could change given that CSAPR is currently stayed under court orders while a federal appeals court rules on the legality of the standard, and MATS faces multiple challenges in Congress and the court system as well.
While there is more of a clear pathway for SO2 and NOx emissions going forward, CO2 emissions from older fossil generation may not be directly addressed in the near future. CO2 emissions will likely decrease on the whole as utilities switch to natural gas to comply with MATS and CSAPR in the coming years, but EPA has yet to address CO2 emissions from existing sources. Earlier this spring, EPA proposed an emissions performance standard for new fossil fuel-fired generation. A settlement agreement with the states and environmental groups indicates that EPA must regulate existing fossil units for those emissions in the future, but EPA Administrator Lisa Jackson said recently that there are currently “no plans” to regulate those emissions. Green groups said they are upping their pressure on the Obama Administration to regulate the sources, but a draft standard is not expected to be released this year.
