Cooking with natural gas in South America, an underestimated environmental and health risk

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The natural gas stoves used by much of South America to cook are more toxic to health and the environment than previously thought. This is confirmed by a recent analysis carried out in homes in Chile, Colombia and Brazil, which found a constant that runs through all three countries: the value of methane emissions measured around the stoves exceeds between six and 49 times the estimated data used by countries to build their national inventories of greenhouse gas emissions.

Natural gas, explains Ricardo Morales Betancourt, a professor at the University of the Andes in Bogotá and co-author of the report, “is almost 90% methane , a fossil fuel. But when burned, just like gasoline and diesel, it is basically converted into carbon dioxide.” That is, no matter how you look at it, gas stoves play an important role in climate change. The surprise, says the expert, is that this responsibility is greater than countries usually report.

When creating what are known as greenhouse gas inventories — basically a report that each country makes detailing what its emissions are and where they come from — governments have two options. One is to calculate them from actual measurements they have made. And the second is to use data held by the Intergovernmental Panel on Climate Change ( IPCC ) to estimate them. In the case of Chile, Colombia and Brazil, emissions from gas stoves have never been quantified in practice, so the countries have chosen the second option.

The analysis, led by the Global Methane Hubs consortium, aims to begin to fill this gap: it assessed the emissions from the stoves of 45 homes in Chile (30 in Santiago and 15 in Temuco), 30 in São Paulo and 23 in Bogotá, and compared the results with those from inventories. While in the Colombian capital methane emissions were six times higher than reported values, in Chile they were 14 times higher and in the Brazilian city up to 49 times higher.

Another warning sign they found, says Morales, is that most emissions do not occur while the stove is in use, but when it is off. “Combustion represents only 25%. And the other 75% comes from small leaks, from the gas that is escaping all the time, even when the stove is off.”

In Colombia, in the days preceding the publication of this report, the country's largest distribution company, Vanti, reported that natural gas prices would rise by 36%. The end of gas reserves has been an inconvenient truth — and one that has been announced — for more than ten years. But the transition, including the one that must happen in homes, is going at a slow pace.

Health alert

Experts also warn that this is not just an environmental alert, but also a health one. Franco Morales, from EBP Chile, an international engineering consulting firm, and coordinator of the analyses in Brazil, says that they also studied pollutants that gas stoves generate — such as nitrogen dioxide, carbon monoxide and benzene — that affect human health. Breathing them in excess can cause everything from headaches to dizziness and unconsciousness. Benzene has even been classified by the International Agency for Research on Cancer (IARC) as carcinogenic to humans.

“Other studies have already warned that emissions inside homes cause respiratory problems, such as asthma in the long term. And it is a significant social cost that no one assumes and that ultimately burdens health systems,” says Morales, from EBP. In Bogotá, for example, low efficiency in gas combustion may be raising nitrogen oxide concentrations above the recommended limits in poorly ventilated environments, according to the report.

Although there is much talk in South America about the energy transition, there is little discussion about how it should be done at the residential level. Wood stoves that are still used in various parts of the region are highly polluting, but gas is no less so. Therefore, this project, says the document, seeks to provide inputs for the gradual elimination of “the use of solid fuels and natural gas appliances in favor of fully electric and efficient alternatives.”

Chile , adds Nicola Borregaard, also from EBP, could take the lead. “Of the three countries analysed, it is the most advanced country towards preparing for this energy transition at the residential level,” he says. “Until June 2024, the assessment we made is that the scenario is very favourable towards electricity, implying that its prices are competitive.” The energy transition, he insists, also has to do with those who consume energy, in whatever form it comes. And the use of gas in kitchens, heating and boilers must also begin to be reconsidered, especially in large cities.