This same study, which tested the emissions from stoves in houses, raised new concerns about indoor air quality due to the high levels of nitrogen oxides.
A team of researchers from California found that U.S. gas stoves emit 2.6 million tonnes (2.4 million metric tons), of methane each year even when they're not in use. This was according to a study published in the journal Environmental Science & Technology. This is equivalent to the annual emissions of greenhouse gases from 500,000 cars, or the amount the United States releases into the atmosphere every three-and-a half hours.
Rob Jackson, a Stanford University climate scientist and co-author of the study, said that "they're constantly bleeding some methane into atmosphere all the time."
The study found that methane is in addition to 6.8 million tonnes (6.2 million metric tons), of carbon dioxide gas stoves release into the atmosphere when they are used and burned. Methane, a greenhouse gas, is more potent than carbon dioxide, but it doesn't last as long in the atmosphere and isn't nearly as abundant in the air.
The researchers looked at 53 California home kitchens, many of which were in bed and breakfasts that they rented. The researchers sealed the majority of the rooms with plastic tarps, and measured the methane emissions to determine when the stoves were operating and when they weren't. Jackson stated that the surprising part was that almost three quarters of methane was released while the stoves were turned off. Jackson said that these are emissions releases the government does not account for.
Eric Lebel (a scientist at PSE Healthy Energy in Oakland) said that the study was a major deal as we are trying to reduce our carbon footprint. He said that much of the benefit is lost when there are leaks.
Jackson stated that many communities have banned the use of gas stoves in new construction. This includes New York City, San Francisco, Oakland and San Jose in the Bay Area.
Frank Maisano, a Washington-based policy and public relations specialist who represents appliance and gas interests, stated that "people can already choose electric appliances" People love gas appliances, especially for their superior performance in colder climates.
Maisano stated that natural gas appliances are more cost-effective and energy efficient than electric ones.
Jackson estimated that about 100 million tons (91,000,000 metric tons) of natural gas leaks into our atmosphere, after taking into account all natural gas extraction and use. The couple million tons of gas stoves is also significant. It's a significant part, and one that we haven’t included in an accurate way in the past.
According to Zachary Merrin, a researcher with the Illinois Applied Research Institute's Indoor Climate Research & Training, the leakage finding is "a very significant takeaway" that ties in with other research that has found large leaks that can account for large amounts of emissions.
Merrin, who was not part of the study's results, stated that the un-combusted methane emissions are "clearly harmful." Emissions-wise, cooking with gas directly is better than using an electric stove powered by fossil fuels but worse than using an electric stove powered by solar energy.
Jackson stated that the methane leak isn’t hazardous to human health and doesn’t pose a threat as an explosive. Researchers found that the methane leak was not dangerous to human health or a potential explosive. However, they discovered high levels of nitrogen oxides in the test results, more than 100 parts per million. Jackson stated that the U.S. Environmental Protection Agency does not have indoor air quality standards for this gas. However, the measurements Jackson took exceeded its outdoor air quality standards. He said that methane does not contain nitrogen but that the byproducts of natural gas oven combustion are the nitrogen oxides.
Maisano advised that people use hood ranges to ensure proper ventilation. Jackson, who owns a gas stove he wants to replace, stated that he has been using ventilation since the beginning of this study.