美国国家公共电台 NPR Large Methane Leaks Threaten Perception Of 'Clean' Natural Gas（在线收听）

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A new study published in the journal Science finds methane emissions from U.S. oil and gas operations are 60 percent higher than previous estimates from the federal government. Now, this comes at a time when we're getting more and more electricity from natural gas, which burns cleaner than coal. But Leigh Paterson reports that burning's not to blame. The problem is leakage.

LEIGH PATERSON, BYLINE: Anthony Marchese has been focused on methane for years. He's a professor of mechanical engineering at Colorado State University. And in 2013 and 2014, he and his team of researchers spent months on the road - driving around to over 100 oil and gas sites in 13 states.

ANTHONY MARCHESE: You'd pull up to one of these facilities in the morning.

PATERSON: The researchers would take out a fancy, expensive camera.

MARCHESE: A camera that can detect, you know, methane, which is usually invisible.

PATERSON: And at times...

MARCHESE: We would see the facility in what we would call an abnormal operating state.

PATERSON: An abnormal operating state - like, natural gas, mostly methane, spewing out of a storage tank.

MARCHESE: We saw that fairly frequently.

PATERSON: Twenty percent of the time, he says. The Environmental Defense Fund put the new methane study together, using Marchese's data and its analysis, along with data from over 100 other independent researchers. They found that overall the methane leak rate is around 2.3 percent of total gas production. Now, that might not sound like a lot, but EDF estimates that this is enough natural gas to power 10 million homes for an entire year. Ramon Alvarez of EDF was one of the lead authors of the study.

RAMON ALVAREZ: The fact is that the magnitude of emissions are so large that it has a material impact on the climate impact of natural gas as a fossil fuel.

PATERSON: Methane is a powerful greenhouse gas. So leaks make natural gas a dirtier source of electricity than assumed. Now, the energy industry is pushing back on all of this.

KATHLEEN SGAMMA: Science is not one study, and then it's all solved.

PATERSON: Kathleen Sgamma is head of the Western Energy Alliance in Denver.

SGAMMA: It's the preponderance of evidence. And there have been several studies which show much lower leakage rates.

PATERSON: And she argues that Colorado producers have done a great job bringing down their methane emissions. And there is something to that. In 2014, Colorado became the first state to tackle the methane problem with regulations. And since then, so other states - like California, New York and Pennsylvania. But at the federal level, the opposite is happening. The Trump administration is working to roll back two Obama-era rules meant to reduce methane emissions. For NPR News, I'm Leigh Paterson.