State lawmakers, acting on research that raised concerns about thousands of natural gas leaks once considered safe, are prodding utility companies to repair them more aggressively.
The House this month approved a bill that would require utilities within five years to plug nearly 16,000 such gas leaks, many of which are decades old and responsible for a significant amount of the state’s heat-trapping gases.
The recent study, by Boston University researchers, found little difference between the dangers of so-called Grade 1 leaks, which utilities are obliged to fix immediately, and Grade 3 leaks, which they consider nonhazardous.
The House bill would also require them to identify the leaks responsible for a disproportionate share of the emissions. An estimated 7 percent of the leaks, known as “superemitters,” contribute about half of all the greenhouse gases attributable to leaks, according to the BU scientists.
The utilities question those findings and oppose the legislation, arguing that such an accelerated schedule would be too expensive and require them to shift crews from other work.
But legislators and environmental advocates say the bill would do more than reduce potential hazards and help the state meet its goals for cutting greenhouse gases. It would also save millions of dollars for ratepayers, who cover the costs of the lost gas, they say.
“Sealing the leaks solves so many problems,” said Representative Lori Ehrlich, a Marblehead Democrat who sponsored the legislation and noted that the utilities are not now required to repair leaks they consider safe. “We’re paying for gas that’s escaping into the atmosphere, and the utilities aren’t motivated to seal the pipes.”
The legislation would also help the state better understand how much methane is being released into the atmosphere, she said. Methane, the primary component of natural gas, is about 30 times more powerful than carbon dioxide over 100 years, meaning small amounts of the gas can have a significant impact on global warming.
“We have the right to know how much is leaking,” Ehrlich said. “It’s a terrible waste.”
Representatives of the state’s utilities, which have never tracked the amount of gas that leaks, said they’re reviewing the research and spending hundreds of millions of dollars to reduce the number of leaks.
They also noted that the state’s methane emissions have fallen, citing a state report that found methane emissions dropped by 62 percent between 1990 and 2012.
“Gas leaks are something the industry takes very seriously,” said Tom Kiley, president of the Northeast Gas Association, a trade group representing utilities. “We’re working very aggressively to reduce the number of leaks in the Commonwealth.”
Kiley said legislation that passed two years ago in Massachusetts was sufficient to accelerate the schedule for repairing leaks, and that the bill the House approved goes too far. He said the utilities plan to seal all leaks within 20 years.
“There are nuances of the bill that are troubling,” he said. “We think the time frame is too fast for some of the work.”
Environmental advocates, however, said the state can’t wait 20 years. They noted that Massachusetts is already facing a steep challenge to meet its legal requirements to cut greenhouse gases.
They cited a ruling last month by the state’s highest court that said environmental officials in both the Patrick and Baker administrations had not done enough to meet the mandates of the state’s 2008 Global Warming Solutions Act, which requires Massachusetts to cut its emissions 25 percent below 1990 levels by 2020.
The court required the state to set specific limits on various sources of greenhouse gases, such as gas leaks.
That decision followed news that the region’s power plants last year released 5 percent more carbon dioxide than the year before — the first year-to-year increase since 2010, according to ISO New England, an independent company in Holyoke that operates the region’s power grid.
The advocates also questioned reports about the decline of methane emissions, saying the state doesn’t really know how much is being released.
They cited a study last year by scientists at Harvard University that concluded the amount of methane leaking was as much as three times greater than previously estimated — a loss that the study valued at $90 million a year and enough to heat as many as 200,000 homes.
The advocates also questioned the utilities’ numbers, noting a recent study said that 5,700 leaks — nearly 30 percent of all those that went unrepaired in 2014 — vanished from the utilities’ reported count between the last day of 2014 and the first day of 2015.
“The bill is needed, because the gas wasted by these leaks is potentially explosive, hurts human health, kills trees, damages the climate, and we ratepayers have to pay for the wasted gas,” said Audrey Schulman, president of the Home Energy Efficiency Team, or HEET, a Cambridge nonprofit.
She urged the utilities to do more to repair the so-called superemitters.
“Fixing these gushers cuts the problem in half in the most cost-effective, least disruptive manner possible,” she said. “It’s a no-brainer.”
The utilities acknowledge that they lack the equipment to identify the most environmentally damaging leaks. They say such devices are far more expensive than what their crews now use. Their existing equipment can only detect the presence of gas in the air.
Sue Fleck, vice president for gas pipeline safety and compliance at National Grid, the region’s largest provider of natural gas, said the company is working on pilot programs with the Environmental Defense Fund in New York and HEET in Massachusetts to identify the larger leaks.
“The industry has been regulated around safety forever, and that’s what governs us,” she said. “But I’m very interested in looking into this.”
The researchers at Boston University, who measured the amount of gas released from 100 leaks in the Boston area, urged the utilities to expedite their repairs, saying that many of the leaks they consider safe pose considerable risks.
“Even small leaks can pose a serious risk of explosion,” said Margaret Hendrick, one of the researchers, whose study was published this year in the journal Environmental Pollution.
“[They] have the potential to be extremely dangerous and should not be discounted.”