Methane leaks from sites like rice paddies, landfills, dairy farms and coal mines could be plugged with the help of gas-guzzling bacteria, helping to curb near-term global warming.
Later this year, researchers in the US will deploy a bioreactor filled with a specially bred strain of methane-eating bacteria at a landfill site in Washington.
They hope the field test will prove that these bacteria, known as methanotrophs, can be deployed in bioreactors to harvest methane from the air, even at relatively low concentrations.
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鈥淪ince existing bacteria are designed by nature to carry out this work, the vision is to harness this natural capability in a modular, scalable technology that can be deployed anywhere in the world,鈥� says at the University of Washington. 鈥淥nce it becomes profitable, this solution can scale to multiple megatons of methane per year, providing a nature-based solution to reducing methane in the atmosphere.鈥�
Methane has a relatively short lifespan in the atmosphere, lingering for around seven to 12 years, but it traps much more heat than carbon dioxide. Cutting methane emissions is therefore a key route to slowing near-term warming of the climate, yet methane emissions have been rising in recent years.
The largest sources of methane emissions are agriculture, fossil fuels and landfill waste, all of which the bioreactors will target. The bioreactors are giant tanks similar in size to a shipping container, housing specially bred strains of Methylomicrobium buryatense 5GB1C, a methanotroph originally found in a lake in Russia.
Lidstrom and her colleagues have been working to improve the microbe鈥檚 ability to harvest methane even at relatively low concentrations of around 100 to 1000 parts per million, similar to the levels found near methane leakage sites like landfills.
The methane-laden air will flow through the bioreactor, allowing the methanogens inside to consume the methane, converting it into proteins, which will be harvested and sold for animal feed, and carbon dioxide. While this means small amounts of greenhouse gas will still be released, the net effect is a reduction in the warming capacity of the air. The team expects the bioreactor to cut methane concentrations by 60 to 80 per cent in air that has been treated.
鈥淭his is a technological solution that can work,鈥� says at the University of Utah, who is also working on the project. A second pilot at the landfill is also being planned for this year, alongside another at an agricultural site, probably a dairy or pig farm.
Once they are scaled up, these bioreactors could be removing 24 million tonnes of CO鈧�-equivalent by mid-century. 鈥淚t鈥檚 an exciting approach,鈥� says at Pennsylvania State University, although she cautions that bioreactors won鈥檛 be a 鈥渟ilver bullet鈥� for all methane emissions.
Scaling up the idea will require commercial investment. The team estimates that $3 million in venture capital funding will be needed to get the bioreactors to market. 鈥淲e need funding to get the engineering developed, to get the pilots out, to demonstrate this and show that it works,鈥� says Swanson.
at the University of Alberta in Canada is working on a similar concept that will use methanotrophs encased in hydrogels to extract methane from wetlands. She says methanotrophs have 鈥渉uge potential鈥� to be deployed to tackle real-world methane emissions. 鈥淲e鈥檙e very fortunate that microbes have evolved this enzymatic capacity to bind methane and oxidise it to carbon dioxide and also assimilate it into biomass,鈥� she says.
