Report: Burning natural gas is better than using coal

STEVE INSKEEP, HOST: The latest news about natural gas arrives in an awkward moment. American gas drilling is booming. The market is expanding. And natural gas is promoted as a clean fuel, far better to run buses or heat homes than oil. A report in Science magazine concludes those benefits are real, but at the same time decades of studies have found that natural gas leaks into the air are a potent contributor to climate change. And the new study finds those leaks are greater than the Environmental Protection Agency estimates. NPR's Richard Harris reports.

RICHARD HARRIS, BYLINE: Every year, the EPA does a survey of natural gas production facilities and estimates how much potent methane gas is leaking into the air. But scientists who study methane gas in the atmosphere note that the government estimate is a lowball.

ADAM BRANDT: These estimates conflict with what's seen in the atmosphere and it's been uncertain for some time now where exactly this gap is coming from, and it's still uncertain.

HARRIS: Adam Brandt at Stanford University is among the team of scientists that drew together the latest information to look at this question. They find that there's 50 percent more methane gas going into the air than the EPA asserts. Some may be from agriculture - cows and rice paddies produce this gas as well. But Brandt says the natural gas production system of wells and pipes and compressors is also playing a role. And that matters when you ask the question, is it better to produce and burn natural gas or coal to generate electricity?

BRANDT: Although we find that EPA is likely underestimating emissions from the natural gas system, we think that it's still beneficial to switch from coal to gas.

HARRIS: At least when it comes to burning fossil fuels for electricity. That's because burning natural gas produces half as much carbon dioxide as burning coal does. But the study says it actually doesn't make sense from the standpoint of climate change to switch from gasoline or diesel to natural gas as a transportation fuel.

BRANDT: There's lots of other reasons we might want to switch to gas. But from a climate perspective, it doesn't look beneficial.

HARRIS: That assessment could change if the gas industry can track down and fix its leaks. Brandt says that might not be so hard to do, based on surveys of natural gas equipment.

BRANDT: A fraction of 1 percent of the sources are responsible for sometimes over half of the emissions. And these are called super emitters. These are basically devices that are broken, corrosion holes in a pipe or a valve that's broken and just leaking gas.

HARRIS: The challenge is to sniff out those leaky spots.

STEVEN HAMBURG: We are currently working on several studies that will try and help quantify how frequent are those large emitters and what are their characteristics.

HARRIS: Steven Hamburg is chief scientist at the Environmental Defense Fund.

HAMBURG: If you can take a limited number of actions and reduce a large percent of the emissions, that's a real win-win for everybody.

HARRIS: EDF is involved in more than a dozen studies of the natural gas system to that end. Last year they published the first - a look at leaks from wells, where operators are using fracking techniques to get at the gas. Hamburg says the studies in progress now are looking more broadly for leaks.

HAMBURG: Some of the studies are looking at pieces of the supply chain. They're looking at gathering lines and processing, doing additional work on well pads and production, then looking at transmission lines and storage, local distribution systems.

HARRIS: As well as gas leaks related to fueling natural gas-powered vehicles. Hamburg says those studies should be wrapped up this year. And he notes that methane is such a potent greenhouse gas, there's a lot of benefit to be had if you can identify and fix the leaks. The EPA had an opportunity to comment for this story but didn't. Richard Harris, NPR News.

Editor's Note: This study was funded by a grant from The Cynthia and George Mitchell Foundation.

To listen to the story, click> NPR Morning Edition.

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