Morten Krogsbøll
University of Copenhagen researchers have used UV light and chlorine to reduce the amount of low-concentration methane in air.
The result gets us closer to being able to remove greenhouse gases from livestock housing, biogas production plants and wastewater treatment plants to benefit the climate.
Methane is the greenhouse gas contributing most to climate change after carbon dioxide. It has more than 80 times the warming potential of CO2 over two decades and is responsible for about 30 percent of the rise in global temperatures, highlighting the importance of tackling its impact to avoid the worst impacts of climate change.
Methane can be burnt off from air if its concentration exceeds 4 per cent. However, most human-caused emissions are below 0.1 per cent.
To remove methane from air, the researchers designed a chain reaction of chemical compounds that relies on chlorine and the energy from light to break down the methane and remove 58 per cent of the gas from air, and as much as 88 per cent in certain tests.
“A large part of our methane emissions comes from millions of low-concentration point sources like cattle and pig barns,” said Matthew Stanley Johnson, the University of Copenhagen atmospheric chemistry professor who led the study. “In practice, methane from these sources has been impossible to concentrate into higher levels or remove. But our new result proves that it is possible using the reaction chamber that we’ve have built.”
The method designed by the team is able to break down the methane roughly 100 million times faster than in nature.
The researchers will now test their experiment in a 40ft shipping container that could become a ‘methane cleaner’: a larger prototype of the reaction chamber built in the laboratory. The device will be connected to the ventilation system in a livestock barn to test the feasibility of installing methane removal mechanism in air purification systems.
“Today’s livestock farms are high-tech facilities where ammonia is already removed from air,” Johnson said. “As such, removing methane through existing air purification systems is an obvious solution.”
Biogas and wastewater treatment plants could also benefit from such systems, as they have been found to be some of the largest human-made sources of methane emissions in Denmark after cattle production.
Earlier this year, the International Energy Agency (IEA) called for the implementation of additional targeted actions to tackle methane emissions. The agency said 75 per cent of methane emissions from oil and gas operations, and half of that produced by coal, could be abated with existing technology at a cost of “less than 2 per cent of the net income earned by this industry in 2022”.
Cutting methane emissions will also have additional benefits, such as preventing nearly a million premature deaths due to ozone exposure and the loss of 90 million metric tons of crops by 2050, the IEA added. This would also translate to roughly $260bn in direct economic benefits.
Moreover, rapid cuts in methane emissions from fossil fuels could avoid up to 0.1°C in global temperature rise by 2030, the agency found.
Johnson has presented the research results at COP28 in Dubai, and his team's findings have been published in the journal Environmental Research Letters.
