A Danish start-up has developed a technology to remove enteric methane emitted by cattle and prevent it from turning into greenhouse gas.
Developers of the technology say positive research results could soon translate into a scalable, workable solution for dairy farms globally as a way to significantly decrease their climate change impacts.
Why it matters: Methane is more than 28 times as potent as carbon dioxide at trapping heat in the atmosphere.
The technology — called the Methane Eradication Photochemical System (MEPS) — was shown to capture 90 per cent of the enteric methane emitted by cattle in a conventional open-sided dairy barn at a research farm in Denmark.
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MEPS was co-invented by Dr. Matthew Johnson, a transplanted Minnesotan who has served for 26 years as a professor of chemistry at the University of Copenhagen. Johnson is the Chief Science Officer and co-founder — along with fellow American David Miller, a communications expert — of Ambient Carbon. The Denmark-based start-up put together the government and industry partnerships funding the research.
“I’m very optimistic about this technology,” Johnson told Farmtario in a recent interview. “The tests are very strong and we’re making sure we’re not missing anything.”
An Aug. 12 news release from Ambient Carbon added the success of the research at the Hofmansgave Foundation research farm “marks a significant scale-up from the previous laboratory prototype, demonstrating the technology’s viability for commercial deployment.”
Johnson said his first successful patents for pollution-fighting technology came in the wake of the Fukushima nuclear disaster in 2011, when a massive tsunami damaged a nuclear reactor in Japan. With governments across Europe searching for alternatives to nuclear power, an earlier start-up founded by Johnson installed greenhouse gas-capturing technology on a massive factory in Poland manufacturing wind turbines.
A second, similar unit was installed at an Italian auto manufacturing plant.
But that technology targeted chemicals that can be described as the low-hanging fruit of greenhouse gases. Production of the styrene required for the wind turbines, for example, produces carbon dioxide, which can be captured relatively effectively and cost-efficiently from exhaust chimneys.
Methane, Johnson said, is much more difficult to target for pollutant extraction.
“It’s the least reactive of any hydrocarbon,” he explained, noting that methane won’t readily dissolve in water and doesn’t react easily with most other compounds. If it’s in high concentrations, it’s flammable and can be ignited and flared off. At somewhat lower concentrations, it can be put through what amounts to a catalytic converter to alter the methane. This process takes a lot of energy, however, and at some point as the methane gets more diluted it simply takes too much energy to remove it to make it worthwhile.
Johnson said a global climate change science organization recently determined that the “tipping point” when it’s no longer energy-efficient to remove methane through the catalytic converter technology is at 1,000 parts per million in the air.
Methane concentrations inside livestock barns typically hover between 40-400 parts per million. Johnson said three-quarters of all sources of methane contributions to greenhouse gases globally come from dilute sources — not just livestock barns but also landfills, water treatment plants and biodigesters.
With more companies bringing to market solutions for the capture of other greenhouse gases, Johnson turned his research efforts towards methane. The breakthrough came, he said, when he combined his team’s research with knowledge handed down from one of his former university professors, Dr. Rudy Marcus, a Montreal-born chemist and winner of the 1992 Nobel Prize for Chemistry.
How it works
The key for the MEPS is chlorine. “It’s kind of like the Achilles heel of methane,” Johnson commented. The technology utilizes light to split chlorine into free radicals, which then bind to the methane and create hydrochloric acid.
“Methane decomposes at a snail’s pace because the gas isn’t especially happy about reacting with other things in the atmosphere,” Johnson said in a 2023 article on the University of Copenhagen website as the Hofmansgave Foundation farm research project was launched. “However, we’ve discovered that, with the help of light and chlorine, we can trigger a reaction and break down the methane roughly 100 million times faster than in nature.”
“The first unit I built was in a six-millimetre quartz tube,” Johnson told Farmtario. Later, his team worked in a swine barn using a “laboratory prototype in a piece of ventilation pipe.” The filter they’re now working with on the Danish research farm is a 5.5 cubic-metre “reaction tube” installed inside a standard 40-foot shipping container situated outside the 250-head dairy barn.
In all cases, the prototypes feature light projected through the cylinder from the ends, the pollutant-laden air pumped into the cylinder, and the light bouncing off reflective material on the cylinder’s walls to repeatedly bombard the chlorine to release its free radicals that will bind to the methane.
“It’s basically like a big tanning salon,” Johnson joked.
A side benefit is that hydrochloric acid, when combined with ammonia, creates ammonium chloride — a salt that’s present in many fertilizers and can be effectively and safely directed to the farm’s manure pit. So ammonia, which can be a problematic emission from livestock barns, is also reduced and/or eliminated.
In the research dairy barn, a tube running the length of the roof near the vents at the ridge collects the warm air as it rises from the cattle. During winter periods when the curtains were closed on the barn, Johnson said the system diverted as much as 90 per cent of the outgoing air to the methane treatment unit.
With the curtains open during warmer weather, that outgoing air capture sometimes dropped closer to 50 per cent.
Johnson stressed that the true test for the technology’s effectiveness will come when it gets installed in a commercial dairy facility. That will happen soon, thanks to a partnership with global dairy processor Danone.
A scaled-up version of the MEPS, housed “in a shipping container that will fit on the bed of a semi-trailer — but barely” is set to be installed next to a 4,600-head dairy barn in Indiana, home of a major supplier for Danone’s North American division.
Johnson’s conservative estimate for methane removal at the Indiana site is 72 per cent of enteric emissions annually. Even at that rate, he said, this will far outstrip the greenhouse gas emission reduction targets of numerous dairy processors globally — which typically fall around 30 per cent over the next two decades.
