A few natural gas wells account for over half of U.S. methane emissions: study

A new study finds that a few natural gas wells account for more than half of the total volume of leaked methane, a potent greenhouse gas, in the United States.

"We're finding that when it comes to natural gas leaks, a 50/5 rule applies: That is, the largest 5 percent of leaks are typically responsible for more than 50 percent of the total volume of leakage," said study co-author Adam Brandt, an assistant professor of energy resources engineering at Stanford University's School of Earth, Energy & Environmental Sciences.

Natural gas is playing an important role in meeting global energy needs and could serve as a "bridge fuel" for countries as they transition from fossil fuels to renewable energy resources.

But natural gas consists predominately of methane, so even small leaks from natural gas wells can create large climate concerns because methane is about 30 times more effective at trapping solar heat than carbon dioxide over a 100-year period.

For the new study, published online in the journal Environmental Science & Technology, Brandt and his colleagues at two other U.S. institutions analyzed about 15,000 measurements from 18 prior studies of natural gas leaks from across the United States using a statistical technique called extreme value theory, which is useful for analyzing infrequent but highly consequential events, revealing that a few outsized leaks were responsible for between 40 and 90 percent of the emissions.

"Other studies have indicated that methane emissions follow a so-called 'heavy-tailed' distribution, but what we're saying is that this pattern is widespread and even more extreme than previously thought," Brandt said n a news release from Stanford, in northern California on the U.S. west coast.

While the findings suggest that super-sensitive leak detectors won't be necessary to have an impact on reducing emissions, they also indicate that the so-called "super-emitters" represent low hanging fruit for methane reduction efforts.

"If companies can identify and fix the leaks in a small number of top emitters, that will go a long way toward reducing methane emissions in the U.S.," Brandt said. "The challenge will be coming up with methods that allow you to find the big leaks as quickly as possible." Endit