Texas Fracking Zone Emits 90% More Methane than EPA Estimated

A sprawling, aggressive effort to measure the climate footprint of natural gas production has yielded striking results:  methane emissions from the Barnett Shale in North Texas are at least 90 percent higher than government estimates.

That conclusion comes from a peer-reviewed study published Monday in Proceedings of the National Academy of Sciences.  The paper is the most sweeping study to emerge from the Environmental Defense Fund's $18-million project to quantify methane leaks from the natural gas industry.  It was written by 20 co-authors from 13 institutions, including universities, government labs, EDF and private research firms.

Overall, the two-year study found that methane emissions from the Barnett Shale are nearly twice as much as estimated by the Environmental Protection Agency's Greenhouse Gas Inventory, and 5.5 times the number from a separate global database.

Co-author Amy Townsend-Small, an environmental studies professor at the University of Cincinnati, said peer-reviewed papers often find larger emissions than EPA estimates.

The EPA's databases are often based on decades-old methodology, Townsend-Small said, adding that the federal agency knows it has "a long way to go."

Understanding the scope of methane leaks is crucial, because the answer will determine whether the ongoing shift from coal to natural gas-fired electricity creates a net benefit for climate change. Although gas power plants emit much less carbon dioxide than coal plants do, even small leaks of methane—the main component of natural gas—could undermine that advantage.

Methane is 86 times more potent than CO2 as a greenhouse gas on 20-year timescales, and 34 times more powerful on 100-year timescales.
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The Barnett produces 7 percent of the nation's natural gas. It was also the first oil and gas basin to use high-volume hydraulic fracturing on a large scale, starting in the 1990s.
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Frank Flocke, an atmospheric scientist who wasn't involved in the PNAS study, said the approach presented in the paper "appears pretty sound."

Flocke, who works for the University Corporation for Atmospheric Research (UCAR) in Boulder, Colo., said he knows many of the study authors and respects their research record.

Because the data came from a single shale basin, Flocke cautioned against making sweeping conclusions.  "Other areas might have different emissions rates, specifically given that the process plants [in the Barnett] seem to be the main emitters.  Depending on how much processing the raw gas needs, total methane 'leak rates' from different natural gas extraction fields...may be very different," he said in an email.  "Much work remains to be done in order to assess the entire" natural gas industry.

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