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Friday, February 14, 2014

New study finds methane emissions worse than estimated, but fixable

U.S. emissions of methane are considerably higher than official estimates but are fixable, according to a new study by a team of researchers from seven universities, several national laboratories and federal government bodies, and other organizations.

"Methane Leakage from North American Natural Gas Systems," published in the Feb. 14 issue of the journal Science, synthesizes findings from more than 200 studies conducted over the last 20 years. It finds that: 
“Actual measurements consistently indicate that methane emission levels are about 50 percent higher than what our national accounts suggest,” says MIT Energy Initiative Director of Research Francis O’Sullivan, who was among the team of authors on the study. (M)any studies have tested gas industry components to determine whether the EPA's emission rates are accurate, and a majority of these have found the EPA's rates too low. 
The study found that part of the problem with EPA’s estimates was “self-selection bias.” Estimating industry-wide leakage rates from voluntary participants – arguably the best-performers – will understate the problem. The alternative is atmospheric studies, of which the study finds: 
Several other studies have used airplanes and towers to measure actual methane in the air, so as to test total estimated emissions. The new analysis found these atmospheric studies covering very large areas consistently indicate total U.S. methane emissions of about 25 to 75 percent higher than the EPA estimate.
However, the analysis also finds that some recent studies showing very high methane emissions in regions with considerable natural gas infrastructure are not representative of the entire gas system. 
Leaking transmission infrastructure is a significant component of the problem and must be fixed. The gas industry, too, must clean up its act, and the study finds that “a few leaks in the gas [processing] system probably account for much of the problem and could be repaired.

While the study affirms the climate benefits of a switch from coal- to natgas-fired electricity,  it finds that:
powering trucks and buses with natural gas instead of diesel fuel probably makes the globe warmer, because diesel engines are relatively clean. For natural gas to beat diesel, the gas industry would have to be less leaky than the EPA's current estimate, which the new analysis also finds quite improbable.
More on this subject here.

The bottom line - methane leaks are economically wasteful, hurt companies' bottom lines, and - most importantly - threaten the planet.  Leaks across the entire value chain, from drilling, to processing, to transmissions, to distribution - must be comprehensively addressed, minimized to the greatest extent possible, more stringently regulated, and thoroughly monitored. Not some day. Now.

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