Wednesday, March 15, 2017

Methane emissions from power plants much higher than EPA estimates, researchers find

More methane is emitted from natural gas-fired power plants and oil refineries than previously thought, says a study by researchers at Purdue University and the Environmental Defense Fund published in the journal Environmental Science & Technology. Methane is a much more powerful greenhouse gas than carbon dioxide, but breaks down in the atmosphere much more quickly. (Purdue University graphic)
Researchers "estimated that emissions from power plants fueled by natural gas could be 21 to 120 times higher than figures in the Environmental Protection Agency's most recent final greenhouse gas inventory," Hannah Hess reports for Greenwire. "For oil refineries, emissions may be 11 to 90 times higher than EPA estimates." Researchers "used Purdue's flying atmospheric chemistry lab—a Beechcraft Duchess light twin-engine airplane equipped with an airflow measurement probe—to collect daily samples at three natural gas power plants and three refineries from July 30 to Oct. 1, 2015."

Paul Shepson, director of Purdue's Climate Change Research Center, said "EPA's greenhouse gas reporting program focuses on how much escapes from belching power stacks, without considering that methane could be leaking from compressors, valves and industrial hardware," Hess writes. He told Hess, "The good news from our study is that while emissions are greater than anticipated, natural gas-burning power plants are still cleaner, relative to burning coal."

Shepson said "The amount of methane escaping from the plants in the pilot study, combined with previous estimates of methane leakage in the supply chain, is still below the 'breaking point at which it would cancel out the positive climate impacts of switching from coal to natural gas," Hess writes.

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