Professional and struggling home cooks alike tend to desire the instantaneous temperature control that comes with a gas stove over electric, but at least one new report may sour that preference.
The gas emitted from household stoves and ovens is not only considered dangerous to public health over time, based on ongoing research, but it is also believed to be aggravating the larger climate crisis more than previously thought. Such findings may only fuel what has been a slow shift among some cities and states to ban new natural-gas hookups in house and apartment construction. Most older stoves are grandfathered in.
The just-released study, from Stanford University, found the emissions from gas stoves in U.S. homes have the same climate-warming impact as that of half a million gasoline-powered cars.
“Natural-gas appliances warm the planet in two ways: generating carbon dioxide by burning natural gas as a fuel and leaking unburned methane into the air.”
“Surprisingly, there are very few measurements of how much natural gas escapes into the air from inside homes and buildings through leaks and incomplete combustion from appliances,” said study lead author Eric Lebel.
“It’s probably the part of natural-gas emissions we understand the least about, and it can have a big impact on both climate and indoor air quality,” he said.
Over one-third of U.S. households — more than 40 million homes — cook with gas. Unlike other gas appliances, such as space and water heaters that are usually placed away from active living spaces, cooking appliances directly expose people to their emissions. These emissions include formaldehyde, carbon monoxide and nitric oxides that can trigger asthma, coughing, wheezing and difficulty breathing.
Hood use and ventilation help reduce concentrations of nitrogen oxides and other co-produced pollutants in kitchen air, yet surveys show that home cooks on average use them only 25% to 40% of the time, the Stanford research showed. The highest emitters were cooktops that ignited using a pilot light instead of a built-in electronic sparker.
Methane: even more potent
Natural-gas appliances warm the planet in two ways: generating carbon dioxide by burning natural gas as a fuel, and leaking unburned methane into the air.
Although carbon dioxide is more abundant in the atmosphere, methane’s global warming potential is about 86 times as great over a 20-year period, and at least 25 times as great a century after its release, say leading environmental groups including the Environmental Protection Agency. Methane also threatens air quality by increasing the concentration of tropospheric ozone, exposure to which causes an estimated 1 million premature deaths annually worldwide due to respiratory illnesses, the Stanford report said.
The researchers measured methane and nitrogen oxides released in 53 homes in California, not only during combustion, ignition and extinguishment, but also while the appliance was off — something most previous studies had not done. Their study included 18 brands of gas cooktops and stoves ranging in age from 3 to 30 years.
Fossil-fuel combustion in buildings, which is mostly tied to heating, is responsible for about 13% of greenhouse-gas emissions in the U.S., according to 2019 figures from the EPA, the latest year for which there are complete data. Competitive natural-gas prices NG00, +9.50% over recent decades have pushed this energy source to replace coal in most power generation — and, in some regions, to replace heating oil in the warming of buildings.
While the EPA does not report emissions from specific residential natural-gas appliances, it does report methane emissions for residential appliances collectively. From stoves alone, the Stanford researchers estimated total methane emissions to be substantially more than the emissions currently reported by the EPA for all residential sources.
New construction goes electric
Last month, New York City created a law that prohibits the combustion of fossil fuels, namely gas, for cooking and heating in select new buildings. The ban will apply to new structures under seven stories tall starting in 2024, and to larger buildings in 2027. The state is considering its own bill.
New York is not alone. Berkeley, Calif., became the first city in the U.S. to ban gas hookups in new construction in 2019. And now at least 42 cities in California, including San Francisco and San Jose, have acted to limit gas in new buildings. Salt Lake City and Denver have also made plans to move toward electrification.
And notably, Ithaca, N.Y., recently took the step to convert all of its buildings, not just new construction, to heat pumps and electric ranges over gas.
New York City’s measure is significant not only because of its population size, but also because of its colder climate.
Some 20 mostly Republican-led states have passed laws barring cities and counties from blocking gas hookups.
Target a different source?
Proponents of keeping fossil fuels in a U.S. energy mix, even those who also want renewables to take a larger share, have said a too-quick jump in electric power use will strain a grid that already reveals weaknesses. Some of the grid’s vulnerability stems from climate change itself. Extreme heat throughout the West led to rolling blackouts in California in the summer of 2020, and extreme cold crippled the independent Texas electrical system in February 2021.
Republican North Carolina state lawmakers, for instance, have written to challenge their governor’s push to renewables, asking instead for greater consideration of natural gas and nuclear power.
“Are you aware that a disruption in the state’s supply of natural gas would cause real-time immediate disruptions to the state’s energy grid?” state Sen. Paul Newton, a former Duke Energy DUK, +1.43% executive, and his two colleagues wrote.
At least one study suggests wind and solar could meet 85% of current U.S. electricity needs.
The gas industry believes home bans don’t target the right problem.
“This is not really a climate solution,” said Daniel Lapato, senior director of state affairs with the American Gas Association, an advocacy group for the natural-gas industry, talking to the nonprofit Pew. “When you start eliminating these options, you have to look at the cost implications to the homeowner.”
Lapato instead wants industry-driven solutions that he argues will have impacts at a larger scale, such as creating more renewable natural gas. Laws to force electrification could stifle industry efforts to scale up that more climate-friendly option, he said. And he and other groups have noted progress made in capping natural-gas leaks along the pipeline and at the point of capture.
Late last year, the Biden administration joined a global effort to target methane from oil and gas operations as part of its strategy to help curb climate change. The news drew cautious support from both environmental groups and drillers.