Study: Methane emissions cancel near-term climate benefits of natural gas

Marie Cusick

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Marie Cusick was the Harrisburg reporter for StateImpact Pennsylvania.

Joe Ulrich / WITF

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June 21, 2018 | 5:08 PM

A new study published today in the journal Science finds climate-damaging methane emissions from the nation’s oil and gas industry are nearly 60 percent higher than Environmental Protection Agency estimates — effectively negating the near-term benefits of burning more natural gas.

As the U.S. shale boom has grown, natural gas has been hailed as the cleanest-burning fossil fuel. It is displacing coal as the fuel of choice for electric power generation, and it’s often pitched as a bridge to a cleaner energy future. But natural gas is mostly methane, and methane leaks out of wells, pipelines, and storage tanks.

While carbon dioxide stays in the atmosphere for centuries, methane lasts only a few decades — but it packs a much bigger initial climate punch. Over a 20-year time frame, methane is 86 times more potent as a heat-trapping greenhouse gas than CO2.

The new paper marks the culmination of seven years of work by academic researchers, oil and gas companies, and the Environmental Defense Fund, which have collectively been trying to gather better, more comprehensive data on methane emissions. The new paper synthesizes existing scientific literature, including non-EDF studies, and estimates the current methane leak rate from U.S. oil and gas systems is 2.3 percent — above the current EPA estimate of 1.4 percent.

“Basically, you’re doubling the climate impact of using natural gas over a 20-year time frame because of these methane emissions,” he said. “Think of it as two climate problems: What’s going to happen in my lifetime? And what’s going to happen in my grandchildren’s grandchildren’s lifetime? [Natural gas] is not helping us in my lifetime — or at least not much. It would be helping in my grandchildren’s grandchildren’s lifetime.”

The paper includes data from 400 well pads in six basins, including the Marcellus Shale, and numerous sites related to pipeline transport and storage. Researchers found most of the problems are related to upstream production — the drilling and storage. Ramon Alvarez, EDF associate chief scientist, said abnormal conditions at some oil and gas sites account for a large share of the emissions. For example, he cited some of the storage tanks holding liquids at gas sites.

“Most wells produce both natural gas and liquids — it includes water and oil, or condensate,” he said. “These are typically 500 gallon tanks; they might be 8 or 10 feet tall, and they’re meant to release pressure at very small amounts, because they’re not meant to hold pressurized gas. So they become the path of least resistance for gas to get out.”

The paper synthesizes previous studies, including both “bottom up” measurements gathered near oil and gas infrastructure on the ground, and “top down” measurements, in which airplanes, satellites or tower networks detect ambient methane. EDF’s full body of methane research since 2012 has included more than 140 researchers at 40 institutions, in collaboration with 50 oil and gas companies.

According to the EPA, the oil and gas industry is the largest source of U.S. methane emissions, followed by agriculture. In February, EDF released estimates showing Pennsylvania’s Marcellus Shale industry is emitting twice as much methane as gas companies report to the Department of Environmental Protection.

Gov. Tom Wolf recently announced updated permit requirements, in an effort to control methane from new oil and gas sources, but his administration has yet to follow through on its 2016 pledge to propose new regulations on thousands of existing emissions sources.

The new paper was funded by the Alfred P. Sloan Foundation, Fiona and Stan Druckenmiller, Heising-Simons Foundation, Bill and Susan Oberndorf, Betsy and Sam Reeves, Robertson Foundation, TomKat Charitable Trust, and the Walton Family Foundation.