Methane Leaks Higher than Previous Estimates

Part of compressor station in Bradford County, PA

A new study finds that methane leaks from the production and transportation of gas could be 50 percent higher than EPA estimates. It also warns that switching vehicles from traditional gasoline and diesel to natural gas will do nothing to slow climate change.

“Methane Leaks from North American Natural Gas Systems” is a policy paper - a collaborative effort by sixteen academics who reviewed and synthesized data from 200 papers published in the past two decades.

The lead author is Adam Brandt, an assistant professor of energy resources engineering at Stanford University. In comments to the press, he explained that official agencies such as the EPA are underestimating leakage of natural gas into the atmosphere. Brandt reminded people that leaked methane is a greenhouse gas, just like carbon dioxide, but 30 times more potent. He also noted that although converting fleets from diesel to natural gas sounds like a good idea – burning gas puts less carbon into the atmosphere than burning diesel – any potential climate benefits would be negated by the leaked emissions from gas drilling and production.

Those gas leaks come from emissions at well pads, storage tanks, old and abandoned wells, abandoned infrastructure, and holes in pipelines. Brandt estimates there are at least 400,000 gas wells – a low estimate given that the US Energy Information Administration tallied up more than 510,000 back in 2010. As for pipelines, “there are millions of miles,” he said in a video press release last week. Brandt characterizes gas as “abundant, cheap and domestic” and seems to approve of using it to replace coal in power production. But the gas industry needs to plug the leaks. It’s in the industry’s best interest, he says. Those emissions represent lost money and if the country hopes to use gas as a fuel “then we need to get leakage under control.”

Tony Ingraffea agrees that there is more methane escaping into the atmosphere than is accounted for by EPA studies. But he criticizes Brandt et al for not going far enough in their review. Ingraffea, a professor at Cornell’s School of Civil and Environmental Engineering, co-authored an earlier study warning that extracting natural gas could do more to aggravate global warming than mining coal.

The problem with Brandt’s study, says Ingraffea, is that it ignores some important data. In particular, the authors eliminated data that seemed “too high” – even though they were actual measurements. Several recent studies have used airplanes and towers to measure methane in the air and found emissions to be much higher than EPA estimates, with some as much as 75 percent higher.

Brandt and his colleagues determined that those measurements were too high, or came from production areas that weren’t representative of the country as a whole, so they dismissed the data. But you don’t get to toss out data you don’t like unless you have very good reason, says Ingraffea.

Another problem, says Ingraffea,  is that the authors simply assert that the 3 million or so abandoned oil and gas wells scattered across the nation are properly plugged and therefore probably not leaking. “The problem with that,” he says, “is that they don’t know where all those abandoned wells are, so they can’t really measure whether they’re leaking or not.”

Ingraffea also takes issue with the study’s claim that, if industry could plug up the leaks, burning gas in power plants would be better for the climate instead of burning coal. In order to make that claim they stretch out their timeframe to 100 years.

“That’s totally arbitrary,” says Ingraffea, “and not based on science.” The Intergovernmental Panel on Climate Change (IPCC) gives us about 20 to 30 years before we approach a tipping point, Ingraffea explains. “We can’t wait that long to start decreasing the carbon emissions from fossil fuel.” He adds that using a hundred-year timeframe is a policy decision that is “…perhaps based on faulty scientific understanding of the climate change situation in which we find ourselves or perhaps political wishful thinking.”

Now is a good time to be reexamining and summarizing previous studies, says Ingraffea. But it’s premature to draw conclusions, because every year there are new studies by scientists collecting actual measurements in the air and on the ground. And the data from these new studies continue to show methane emissions at rates much higher than previously thought.

Looking at the big picture, Ingraffea believes the study asks the wrong question. Instead of trying to pin down an average emission rate of methane, they should be asking how much risk we are willing to take. “Risk is the key issue of any policy decision,” says Ingraffea. Sometimes there are bad things that can happen, but they have little consequence so we live with them – even if they happen frequently.

“But this is one thing with a major consequence, so we have to be conservative in our risk taking,” says Ingraffea. Using the average value of methane emissions is inadequate, he says. Policy makers need to peg emission allowances closer to the lower end – and even then acknowledge the uncertainties surrounding that level.

“In the meantime, many of those crucial next 20 years are going by,” Ingraffea warns, “and we should have already started to reduce all fossil fuel use, not increase it as this study proposes.” 

This article first published in Tompkins Weekly, February 24, 2014.