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Methane leaks across US pose a much greater threat than Aliso Canyon — The Guardian

By Leah Messinger

When Stephen Conley, an atmospheric scientist and pilot, saw an emissions indicator skyrocket in his Mooney TLS prop plane, he knew he had found a significant methane leak. His gas-detecting Picarro analyzer indicated he was flying through a plume of gas escaping at 900kg per hour. The colorless, odorless gas was enough to cover a football field to a height of 20 feet in a single day. But this flight wasn’t over the highly publicized Aliso Canyon in Los Angeles; Conley was circling the Bakken Shale, a rock formation in western North Dakota that has been aggressively pumped for oil and natural gas.

Day in and day out, small leaks in oil and gas producing regions like the Bakken Shale are emitting methane in quantities that collectively rival or even exceed Aliso Canyon. New figures released by the Environmental Protection Agency (EPA) last month indicate the potent greenhouse gas is being emitted from leaks across the US in quantities “much larger” than previously thought.

“There’s all these small leaks everywhere and they eclipse [Aliso Canyon],” said Paul Wennberg, professor of atmospheric chemistry and environmental science and engineering at the California Institute of Technology.

Only in the past three years has there been a concerted effort to study emissions from oil and gas producing regions. Many of the new studies have been coordinated by or received funding from the nonprofit Environmental Defense Fund (EDF) as part of its comprehensive project to track methane emissions from natural gas production and transmission.

The results have been striking. Researchers from the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado Boulder found methane escaping from Utah’s oil and gas producing Uintah Basin at 55 metric tons per hour. The same researchers found oil and gas related methane in Colorado’s Denver-Julesburg Basin leaking at 19.5 metric tons per hour. In the Barnett Shale area of North Texas, methane emissions were sampled at 60 metric tons per hour.

By comparison, if the emissions from Los Angeles’s Aliso Canyon leak were averaged out over its nearly four-month duration (it was deemed permanently sealed on 18 February) that leak would be equivalent to an estimated 35 metric tons per hour. Aliso Canyon is expected to be California’s largest single contributor to climate change.

Leaks found in Utah, Colorado and Texas, however, are believed to be ongoing and there are currently few efforts to contain them. (Colorado recently enacted new emissions laws, though their efficacy has yet to be determined.) There are many other areas where no testing has been done at all.

“Aliso Canyon maybe represents one half of what’s coming out of a small basin like the Denver-Julesburg area, but a much smaller fraction of something like the Uintah Basin or Barnett in Texas,” said Colm Sweeney, lead scientist for the NOAA Earth System Research Lab Aircraft Program.

Researchers at NOAA report finding methane – the primary component of natural gas – leaking from the entire natural gas supply chain, from extraction to storage to transmission. The leaks can come from improperly sealed fittings, faulty valves and compressors, improperly closed hatches and many other sources, stemming from both human error and equipment failure. “There’s no really compelling smoking gun that one particular type of thing leaks more than another,” said Dan Zimmerle, director of the Electrical Power Systems Laboratory at Colorado State University.

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