The hunt for methane gas leaks goes high tech
Scientists are trying to find leaky gas wells and pipelines. They want to know how much of this infrastructure is leaking methane - a potent greenhouse gas.
Naomi Zimmerman is checking a computer screen inside a white van that looks like it came straight from an episode of Storm Chasers.
“There’s a blue line with the green line, but you can’t even see it anymore because the fit is spot on. We’re ready to do our calibrations,” she says.
Zimmerman is leading a team of researchers from Carnegie Mellon University looking for methane here in the rolling hills of Northeastern Pennsylvania.
The team’s first stop is about half an hour away, next to a pipeline tucked onto the back edges of a local farm. They park their van, and turn on the equipment. Scientists see a spike on the levels on their computer screen.
The team is picking up about 1.2 parts per million of methane, or about 12 times the amount they would normally see coming off a well pad. Then, they see the levels go even higher.
"It just went up to 9 ppm. Wow. Wow," says Zimmerman.
These readings could help Zimmerman and the other researchers answer what’s become an important question. How much natural gas is leaking into the atmosphere?
One of the key selling points of natural gas is that burning it produces far less carbon dioxide than coal—a fuel that gas has quickly replaced as the nation’s top source for electricity. So if you’re burning gas instead of coal to make electricity, that’s good from a climate change perspective. But when that natural gas escapes from pipelines, the gains from using natural gas can quickly dissipate. That’s because over a 20-year period, methane is 84 times more effective at trapping heat than carbon dioxide.
“If you’re not burning the natural gas—and you’re releasing pure methane into the atmosphere—the methane has a much higher global warming potential than carbon dioxide,” says Zimmerman.
Zimmerman’s colleagues at Carnegie Mellon have found the EPA has been underestimating methane leak rates for years. But they’re still not sure exactly how much methane is escaping the country’s oil and gas system.
Allen Robinson was part of a team that found methane emissions in Texas’ Barnett Shale were 90 percent higher than estimates in the EPA’s Greenhouse Gas Inventory. The group also found that most emissions were coming from a very small number of sources. But even Robinson says these studies still represent at best an educated guess as to how much methane is actually leaking out of the natural gas system.
“It’s a very messy problem,” Robinson says. “You’d think ‘Wow. Shouldn’t we know that by now?’ But we don’t, really.”
A tricky question to answer
Why can’t they figure this out? One reason is the sheer number of places where gas can escape.
Mark Boling is a vice president for Southwestern Energy.
"We're not talking about one facility where you have one stack and say there's your source it's coming out there," he says.
Instead, each step of the natural gas network contains hundreds of places where gas could escape.
Southwestern is one of several companies that have signed on to a pledge to reduce their methane emissions to less than one percent. That’s a 50% decrease from current EPA emissions estimates. Boling says spending money on equipment that can prevent methane leaks is good for business.
“Whatever methane we can save from going up into the air and keep in the pipeline—whatever we get for that will help defray the cost,” Boling says.
The U.S. Environmental Protection Agency and several states, including Colorado and Pennsylvania, have begun implementing methane regulations for the oil and gas industry. Boling isn’t a fan of these regulations because he says they prescribe equipment for companies to use that may not be necessary or effective. To him, it’s better to let companies decide how to reduce their own emissions.
“You’re basically telling them we have 100 different sources, 20 are the problem—but I want you to replace all 100,” Boling says.
Other companies are also starting to take methane pollution seriously. In June, Montreal-based GHG SAT launched “Claire”—a satellite equipped with high-resolution methane sensors. Among the companies paying for the data Claire will send back are ExxonMobil and Shell.
These companies can make money with this data because they’re already subject to carbon pricing systems in British Columbia and Quebec, according to Stephane Germain, CEO of GHG SAT.
“Industrial operators would be financially motivated to better understand their emissions so that they can control them and ultimately reduce them,” Germain says. “Really what they’re doing at that point is reducing their own financial risk.”
NASA has been using satellites to measure greenhouse gases for years. But with higher-resolution sensors, satellites could become even more important in the search for methane leaks.
Harvard climate scientist Daniel Jacob used satellites to detect a large pall of methane over the central United States. The amount of methane he detected was 30 percent higher than current EPA estimates would predict. His study couldn’t determine if drilling or some other source—like agriculture—was the cause. But Jacob says satellites could be an early warning system to help on-the-ground teams find and fix leaks.
“They can tell you, ‘Aha! You’ve got a hot spot here.’ Then, once you figure out from space you have a hot spot, you can dispatch ground-based instruments—or maybe low-flying aircraft—to figure out where this methane is coming from.”
Technology to do this is improving. Jacob’s previous paper used satellite data with a resolution of 10 square kilometers. His current project is using Claire, which has a resolution of 50 square meters. Claire is scheduled to start sending methane readings back to Earth this fall.
Reid Frazier is a reporter with the environment news program, The Allegheny Front.