Gas stoves contribute more to global warming than previously thought due to constant tiny leaks of methane when turned off, a new study finds.
Posted at 3:03 p.m.
The study, which tested emissions around stoves in homes, raises new concerns about indoor air quality and the health implications of the nitrogen oxide levels measured.
Even when not operating, gas stoves in US homes emit 2.4 million metric tons of methane — in units of carbon dioxide equivalent — into the air each year, a team of California researchers found in a study published Thursday in the journal Environmental Science & Technology. This is equivalent to the annual amount of greenhouse gases of 500,000 cars or what the United States emits into the air every three and a half hours.
They constantly pump a little methane into the atmosphere all the time.
Rob Jackson, climatologist at Stanford University and co-author of the study
This methane is in addition to the 6.2 million metric tons of carbon dioxide gas stoves emit into the air when they are in use and the gas is burned, according to the study. Methane is a greenhouse gas that is dozens of times more potent than carbon dioxide, but does not stay in the atmosphere as long and is not as abundant in the air.
The researchers looked at 53 home kitchens in California, many of them in Airbnb-like establishments they rented. They sealed off most rooms with plastic sheeting, then measured emissions when the stoves were on and when they weren’t. Amazingly, three-quarters of the methane released was while the stoves were off, Jackson noted. These are emissions that the government ignores, he pointed out.
Not so green, cooking with gas
“It’s a big deal because we’re trying to really reduce our carbon footprint and we’re saying gas is cleaner than coal, which is true,” said study lead author Eric Lebel. scientist at PSE Healthy Energy, an Oakland nonprofit. But he points out that much of the benefit disappears when leaks are taken into account.
Many places have banned the use of gas stoves in future new construction, measures that will come into effect in the coming years, including New York and the cities of San Francisco, Oakland, San Jose and Berkeley, said Mr Jackson.
“People can already choose electric appliances if they want to,” said Frank Maisano, a political and public relations expert from Washington who represents gas and appliance interests. “People like gas appliances because they work better, especially in colder climates. »
“Natural gas appliances are generally more energy and cost efficient than their electric counterparts,” Maisano noted.
The finding of leaks is “a very important finding” and matches other work that has found there are often large leaks that account for a large portion of emissions, said Zachary Merrin, an engineer with the research group. and indoor climate training from the Illinois Applied Research Institute.
Mr Merrin, who was not part of the study, said the emission of unburned methane is “clearly bad”. “When it comes to emissions, cooking directly with gas is a better option than using a fossil fuel-powered electric cooker, but a worse option than using a solar-electric cooker. »
The methane leak is not dangerous to human health or as a possible explosive, Jackson said. But in testing, researchers found high levels of nitrogen oxides, over 100 parts per billion. Mr Jackson said the United States Environmental Protection Agency does not have indoor air quality standards for this gas, but the measures they have taken exceed the air quality standards. outside. Although methane does not include nitrogen, nitrogen oxides are byproducts of combustion in natural gas stoves, he said.
Mr Maisano said people should always use hooded cookers and ensure they have adequate ventilation. Mr Jackson, who has a gas cooker he is considering replacing, said he had never used ventilation before this study but now does every time.