Two US doctors’ groups have denounced burn of hydrogen-methane blends in indoor spaces on the grounds that it supercharges the symptoms of asthma and dementia and raises the likelihood of fatal gas explosions – with one organisation saying it “puts lives at risk”.
Giant doctors’ union American Medical Association (AMA) and Physicians for Social Responsibility (PSR), a social justice campaign group led by health professionals, separately warned that hydrogen’s low ignition point increases the likelihood of explosions, presenting a significant safety hazard inside buildings.
“Hydrogen ignites more easily and is more explosive than methane, thus increasing the danger of explosions in buildings,” said PSR in a report released yesterday. “It places lives at risk.”
Furthermore, both groups warn that blends of hydrogen and methane increase the emission of nitrogen oxides (NOx) compared to burning methane alone, which will raise the risk of NOx-associated diseases including asthma.
Nitrogen oxide (NO2), a NOx emission, is linked to “emergency department visits and hospital admissions for asthma and is associated with higher rates of dementia in older adults”, PSR noted.
These impacts will disproportionately fall on people from disadvantaged backgrounds, who are more likely to live in rented housing with older and inadequately ventilated stoves that result in higher levels of indoor air pollution, it added.
“I’m deeply concerned about the health and safety risks associated with burning a hydrogen-methane blend in our homes, especially for vulnerable populations and communities who already face disproportionate health burdens due to air pollution and climate change,” said Barbara Gottlieb, director of environment and health, PSR.
“Hydrogen blending will increase, not decrease, our reliance on fossil fuels, and that will perpetuate existing health inequities.”
PSR’s report comes hot on the heels of AMA’s resolution earlier this month condemning hydrogen blending with natural gas on principle, warning that exposure to NOx can cause asthma as well as exacerbate it.
The groups’ position tracks with a report published in March by San Francisco-based climate think-tank Energy Innovation, which also warned about the risks of explosion and NOx emissions in space heating. In fact, NOx emissions via natural gas stoves already increase the risk of asthma in children by 42%, Energy Innovation said.
The AMA, which has resolved to campaign against hydrogen blending, stressed that pure hydrogen emits six times more NOx than methane.
With Californian gas distributor SoCalGas currently constructing a model home to test blending safety in heating appliances, PSR also called for independent research to determine whether hydrogen can be delivered into buildings safely.
“Most hydrogen demonstration projects are co-sponsored by fossil fuel companies and few studies of safety and health are conducted by researchers not receiving funding from fossil fuel interests,” it said, warning that many existing heating appliances are not designed for blends of hydrogen and methane.
But the UK gas industry pointed to the HyDeploy demonstration project at Keele University in England, where 20% blends of H2 have added to the existing gas network since 2019.
Run by UK gas companies Cadent and Northern Gas Networks in collaboration with the country’s safety regulator, the Health and Safety Executive (HSE), and Keele University, the pilot used existing appliances with oxygen deficiency sensors attached to measure the potential fire risk.
“Analysis of the test data concluded no increase in gas fire risk as a consequence of introducing a hydrogen blend,” the project report said.
The issue around NOx remains unclear however. Gas industry sources claimed to Recharge that, depending on the efficiency of the burner, H2 blending can reduce NOx emissions compared to methane alone – however the corroborating data is yet to be published.
“I just can't tally US lab research with real world trials in the UK, trials overseen and signed off on by the HSE,” said the industry source. “The two things just aren't comparable.”
UPDATED to include background information on the HyDeploy demonstration project