A new study of natural gas infrastructure in Connecticut says harmful amounts of methane are leaking from aging underground gas pipes. The findings add to an emerging body of science demonstrating the scale of methane leaks in America.
Methane is the main part of natural gas. Like carbon dioxide, it’s a greenhouse gas, trapping heat in the atmosphere and contributing to global warming. But Nathan Phillips, a professor at Boston University, said there’s a big difference.
“Methane is like carbon dioxide on steroids,” Phillips said. “It’s dozens of times more powerful in heating up the atmosphere than CO2 is. So if you leak that methane, instead of burning it, it’s very damaging to the climate.”
And one way methane can leak here in New England? From old buried pipes.
To quantify those leaks, Phillips and his team rigged up a high-tech “gas sniffer” to a car outfitted with a GPS. They drove around three cities in Connecticut, pulling in air from surrounding sidewalks, pinging their location and measuring the amount of methane to produce a highly resolved map of where those leaks are happening.
Tim Keyes, one of the study’s lead authors, said this mapping work, when combined with a 2016 leak survey he did in Hartford, showed hundreds of previously unidentified leaks.
“The leak indications are still prevalent and persistent,” Keyes said. “There are still an unsettling number of leaks per mile that can be observed.”
In Hartford, his team found enough methane leaking from pipes each day to heat more than 200 homes. Leaks were also found in Danbury and New London.
Connecticut Natural Gas and Southern Connecticut Gas, which are owned by Avangrid, also the parent of United Illuminating, declined a request for an interview about the study.
But in a statement, Ed Crowder, a spokesperson for CNG and SCG, said the utilities upgrade about 50 miles of piping annually with pipes “less prone to leakage” and have a “robust program to monitor and respond to natural gas leaks.”
SCG has about 2,500 miles of mains and CNG has about 2,100, Crowder said.
Tricia Taskey Modifica, a spokesperson for Eversource, which owns Yankee Gas, Connecticut’s largest natural gas distributor, said the company annually invests tens of millions of dollars to upgrade gas pipes. It's replaced hundreds of miles of gas lines around the state since 2011, including in Danbury and New London.
Eversource has about 3,500 miles of gas mains in Connecticut, according to the Public Utilities Regulatory Authority.
Jessika Trancik, an associate professor at MIT who was not involved with the Connecticut study, said the new paper is advancing the science of how we pinpoint leaks, which are notoriously pricey to fix and difficult to track.
“It’s sort of a hidden, invisible problem,” Trancik said. “So that’s part of why we’re having such a hard time getting a handle on how large are these methane leaks actually?”
But leaky city pipes are just one contributor to lost methane. Bob Howarth, a professor of ecology and environmental biology at Cornell University, said there are many other spots on the production chain where methane is lost into the atmosphere.
“We drill wells. We hydraulically fracture the wells. We pull the gas up. We process the gas. We store it. We then put it in high-transmission pipelines,” Howarth said. “We finally get toward cities and suburbs, where we put it into lower-pressure transmission pipelines, and the fact is, that methane is emitted at each and every one of those steps.”
In 2019, Howarth published a study that said at least one-third of the global increase in methane over the last decade is coming from shale gas development in the United States.
He said studies like the Connecticut paper are valuable additions to a growing body of evidence, including work by Nathan Phillips in Boston, that show old city pipelines for natural gas are also contributing to that global uptick.
“What this new paper does is … just show the magnitude of the number of leaks,” Howarth said. “It’s really quite striking when you look at some of their visuals.”
And while companies are supposed to step in to fix major leaks, especially if they pose safety risks, Howarth says the gas industry doesn’t have much incentive to fix other methane leaks.
“Gas that’s leaked on its way to the consumer can be charged off, collectively, to the consumers by the company,” Howarth said. “So they’re actually making money off the gas that is leaking as well as what they sell to the customer.”
But the utilities said they remain vigilant of methane leaks in Connecticut towns.
“We patrol our entire distribution system every three years to identify and address leaks, and our on-time response rates are among the best in the industry,” said Crowder, the spokesperson for CNG and SCG.
“We use proven state-of-the-art leak detection equipment and closely, constantly monitor our system and have seen a 24 percent reduction in leaks across our entire system in Connecticut in the last few years,” said Modifica, the spokesperson for Eversource.
Both Howarth and MIT’s Trancik said fixing leaky pipes is important. But both agree the real solution is to shift away from fossil fuels. Trancik said all that uncertainty about how methane is leaking and where is just one more argument for transitioning to a cleaner grid.
“We shouldn’t be hamstrung by that uncertainty. Instead, we can take that uncertainty into account and say, ‘OK, that’s a risk.’ This means we may need to accelerate our transition plan away from natural gas,” Trancik said.
And hopefully, stop the release of another, lesser-known greenhouse gas.