Significantly more methane is spewing into the atmosphere from natural gas wells and other drilling operations in North Texas’ Barnett Shale fields than previously estimated, according to a new series of studies, raising new questions about the relative benefits of drilling for more gas instead of burning coal.
Well pads, compressor stations, processing plants and other equipment used in gas production across the 25-county region leak 50 percent more of the greenhouse gas than the federal Environmental Protection Agency has estimated, according to the 11 peer-reviewed papers published Tuesday in the journal Environmental Science and Technology. Human error and faulty equipment accounted for most of the emissions, the studies found.
The research in the 5,000-square-mile Barnett, one of the country's largest gas fields, adds to a growing – but still incomplete – body of research into the true climate benefits of shifting away from coal-fired electric plants in favor of natural gas, now abundant thanks to hydraulic fracturing.
Power plants burning natural gas emit far less carbon dioxide than traditional coal-fired plants, helping to reduce climate impacts. But extracting oil and gas through fracking releases methane, the main component of natural gas and a greenhouse gas up to 34 times more potent than carbon dioxide.
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Natural gas industry representatives have pointed to EPA data showing total greenhouse gas emissions in the U.S. have dropped amid a drilling surge to suggest that fracking yields climate benefits. But along with other recent research, Tuesday’s papers suggest that the federal government has been vastly underestimating methane emissions, particularly in the south-central portion of the country, where oil and gas drilling is most prevalent. That was largely due to a lack of data on all stages of the gas supply chain, the researchers said.
With funding from the Alfred P. Sloan Foundation, the Environmental Defense Fund teamed up with researchers at 20 universities and private firms to measure the industry’s methane footprint across the densely populated Barnett, where petroleum companies first used a combination of horizontal drilling and fracking to unlock natural gas. The scientists gathered their data in October of 2013.
The studies pegged the industry's methane leakage at roughly 1.2 percent of all natural gas produced in the region and showed that oil and gas production accounted for 64 percent of total methane emissions.
Many wells and other facilities leaked relatively small amounts of the greenhouse gas. But much larger amounts of methane escaped at other sites at rates higher than what the EPA has recorded in its Greenhouse Gas Reporting Program. The leaks came largely from operator mistakes, poor maintenance, or simple wear and tear on equipment – conditions that experts call preventable.
“A lot of it is human error. Somebody will leave a hatch open, and nobody goes back to the facility for more than a month, so it’s leaking this huge amount of methane out of the top,” said Robert Talbot, a University of Houston professor of atmospheric chemistry who was part of the research. “We’re hoping now that most of the companies will take a look at what they’re doing, and go ahead and do good maintenance.”
Leaks at the sites ranged from 0.01 percent to 47.8 percent of natural gas produced, with the vast majority on the lower end. Compressor stations and processing plants were found leaking at particularly high rates — far above EPA estimates. The region’s 275 compressor stations — which help process and transport gas — accounted for 40 percent of total oil and gas emissions.
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Even so, industry representatives saw the new studies as bolstering arguments about fracking’s role in curbing greenhouse gases.
In previous studies, EDF has calculated a leakage rate of 2.7 percent as the breakeven point for the fracking’s climate benefits – where the effects of producing natural gas cancel out the benefits of burning it instead of coal. The rate calculated in its Barnett Shale studies sits clearly below that threshold.
“There’s nothing inherent about Barnett Shale development, or even shale gas development nationwide that leads to high leakage rates,” said Steve Everley, a national spokesman for Energy In-Depth, which promotes the petroleum industry. “What this study and other studies have actually suggested, is that the overwhelming majority of oil and gas operations are actually done very safely with very low leakage rates.”
An EDF study last year found that the country’s petroleum industry could curb methane emissions by as much as 40 percent by 2018 by making investments that could save money in the long run, such as by finding and repairing pipeline leaks, replacing compressor equipment and capturing the gas before it escapes. And the group hailed methane rules recently implemented in Colorado, another drilling hotbed.
The Obama administration early this year announced a proposal to slash oil and gas sector methane emissions by almost 50 percent over the next decade, but has yet to release specifics.
Everley, who welcomed the EDF research, said the industry is already taking steps to address the problems on its own.
“The industry is going to be continuing to do what it has been doing because that is already delivering progress,” he said. “Let’s not try to fix something that isn’t broken.”
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