Leaking methane from natural gas-burning stove tops is releasing the greenhouse-gas equivalent of hundreds of thousands of cars, and cooking on gas stovetops is posing a risk to health, according to new research.

ABC Science By environment reporter Nick Kilvert

In findings that have taken researchers by surprise, more than three quarters of methane emissions from stovetops were leaking into houses while the appliances were not in use.

They’re the results from a study published in the journal Environmental Science and Technology, which looked at natural-gas emissions from stovetops in households in the United States.

The researchers are hoping to replicate the study in Australia, and believe the US results are largely comparable with the situation here.

“COVID-willing, we hope to sample in Australia over the next year or two, probably in 2023,” said study co-author, Professor Robert Jackson from Stanford University.

"Our biggest surprise was that most of the methane we measured leaked to the air while the stoves were off."

While the rate of methane leakage was higher while the stoves were in use, the amount of time spent not in use meant the overall volume of methane leaked was greatest during this time.

Previous studies have found methane emissions from gas stovetops to be lower than this one, but they only measured emissions when the stoves were on, Professor Jackson said.

According to today’s results, gas leaks from stovetop cookers in 40 million homes in the US produced about 28,000 tonnes of greenhouse gases every year, or the equivalent of the emissions from around 500,000 petrol cars. That’s comparing methane and vehicle emissions over a 20-year period.

The research did not include finding where the leaks were coming from, but Professor Jackson said they most likely originated from leaking fittings or couplings near the stoves.

Children most at risk

The researchers based their projections on the emissions from stovetops from 53 homes across California. While methane is emitted while the stove is not in use, nitrous oxides and fine particulate matter (as well as methane) are released during combustion. They build up quickly in the household while the stoves are on and contribute to respiratory diseases, especially in children and the vulnerable, according to public health physician Dr Kate Charlesworth. “Children are for a range of reasons more at risk from air pollution,” said Dr Charlesworth, who also works at the Climate Council.

"They have smaller lungs … and a higher respiratory rate."

She worried that equity issues meant that more vulnerable individuals and renters may be most impacted.

“It’s the most vulnerable that are being hit hardest — the young, the elderly, the asthmatic,” Dr Charlesworth said.
Energy and climate change policy expert Donna Green from UNSW said she wasn’t surprised by the findings, and the fact we’re still burning fossil fuels in our homes “is nuts”.

“We’ll be in shock in decade’s time that we actually did this,” Associate Professor Green said.

"There's no excuse other than a lack of awareness and a really good campaign by the fossil fuel industry to sell us something we [don't need]." "Every [house] from now on should be putting in induction, especially because the price of induction stove tops is so cheap now."

The Climate Council published a report last year that estimated that cooking with gas was responsible for around 12 per cent of the “burden of childhood asthma” and was comparable to household cigarette smoke.

Households the tip of the iceberg

The issue of fugitive gas emissions from post-meter appliances is just the tip of the iceberg when it comes to Australia’s overall methane emissions, according to Tim Baxter, a climate solutions researcher with the Climate Council. There is little monitoring of fugitive gas emissions in Australia — from the point of extraction, right through the supply chain — and it’s very probable that we’re underestimating our methane emissions as a result, he said.

"This is a broadly unmeasured problem and it's an instance of what is not measured is not managed."

“This [starts at] the very, very broad scale — entire gas basins,” he said.

Methane is a powerful greenhouse gas with a global warming potential of more than 80 times that of carbon dioxide over its first 20 years. However, it doesn’t persist in the atmosphere for as long as CO2. Based on its global warming potential and current rates of emission, methane is considered the second-most significant greenhouse gas behind CO2.

Satellite data analysis from a London-based data analytics company last year raised serious questions about the accuracy of Australia’s methane emissions reporting. According to their analysis of mines in the Bowen Basin, Australia had only accounted for about one third of our methane emissions from the region.

At the time, a spokesperson for The Department of Industry, Science, Energy and Resources said the department was developing its own national methane monitoring system using Sentinel data. Dr Charlesworth said the health and climate impact of methane meant that moving from gas to electric and induction stovetops was an imperative in decarbonising.

"At the very least, open windows, use an extraction fan, keep the kids out of the kitchen." "From a health perspective, as a doctor and mother, there's a double impact from gas." "Not only is it a major source of health pollution in peoples' homes, but it's also a fossil fuel."