August 10, 2013
A new study has found “alarmingly high” levels of methane leaking out of natural gas wells in Utah, adding fodder for a simmering debate over the fracking boom’s potential to alleviate climate change.
A team of National Oceanic and Atmospheric Administration (NOAA) scientists found that between 6.2 and 11.7 percent of methane—the key component of natural gas—was leaking out of wells, pipelines and compressor stations they measured on one day in February, 2012 in a heavily drilled part of Utah.
The paper, to be published by the journal, Geophysical Research Letters, points out that this number is well above the EPA’s current estimate of 1.5 percent methane leakage.
“It was a lot higher than we ever expected,” says Colm Sweeney, the study’s lead author and a scientist at NOAA’s Earth System Research Laboratory. Though, he adds, the group had seen methane spikes on the ground near some of the natural gas wells it monitored.
A recent scientific paper estimated that if more than 3.2 percent of methane leaked out of natural gas wells, pipelines, and compressor stations, it was no better than coal in terms of global warming over a 20-year time span. That’s because methane is a much more potent greenhouse gas than carbon dioxide (CO2), the biggest source of greenhouse gases and the main byproduct of burning coal. Over a longer term, methane loses its potency as a greenhouse gas. But over a 20-year time span, it’s 72 times more potent than CO2, according to the Intergovernmental Panel on Climate Change.
The authors flew over the Uintah basin several times in the winter of 2012. On Feb. 3, 2012, they took advantage of exceptionally good weather, after high winds had essentially blown other pollution away. That meant that any methane they found in the air was likely tied to new emissions from gas wells.
They then compared their numbers to natural gas production reported for the area, and came up with an estimated amount of leakage that day. “Our result is a snapshot, but it’s a real snapshot,” Sweeney says.
By contrast, the EPA’s estimate is based largely on emissions estimates based on observations made in some cases in the 1990s.
“Their approach is like the Nielsen (rating) approach,” he says. “EPA is saying, ‘We have a certain type of well, that produces so much emissions,” and extrapolates its estimates of total emissions from there.
Sweeney says using natural gas still had the potential to cut down on our greenhouse gas emissions. “This is not a show stopper in any way,” he says. But finding out where the leaks were coming from was important, he says.
Sweeney adds that many of the wells monitored were on tribal lands, and so may not be subject to the same sets of regulations elsewhere.
Steven Hamburg, scientist at Environmental Defense Fund(EDF), calls the findings “alarmingly high." But he cautions that the calculations could be the result of an abnormally high level of natural gas activities in the basin on the day the measurements were taken.
“More investigative work is needed before we can claim to understand what is driving these apparently large emissions,”Hamburg says.
Michael Levi, at the Council on Foreign Relations, expressed similar concerns in his blog post on the paper.
“They only have three hours of observations, and no direct way of knowing whether those observations are representative of methane emissions over longer periods of time,” Levi says.
A team of scientists at EDF and the University of Texas(UT)will also publish a paper on methane emissions in “the coming weeks” that will assess these estimates.
Robert Howarth, the Cornell professor whose estimate that shale is worse than coal has been often cited by opponents of fracking that shale gas should not be considered “clean”, said in an e-mail he’d be leary of the EDF-UT paper, because the team is working with nine industry partners to produce the study.
“That means, presumably, that they are sampling at the places industry wants them to sample. Th[is] seem[s] likely to produce an estimate of the best-case scenario of how low emissions can go, when industry knows they are being watched," Howath says.
Sweeney’s team is also studying gas emissions from natural gas drilling in the Barnett Shale in Texas and in Colorado, near Denver.