Methane-busting “reaction chamber” set to slash GHG emissions from livestock farming

22 Dec 2023 --- Scientists in Denmark have devised a methane eradication photochemical system (MEPS) that uses light and chlorine to eliminate low-concentration methane from air. With a 58% removal efficiency and 30 liters per minute flow capacity, the technique can reportedly remove greenhouse gasses (GHG) from livestock housing and biogas production and wastewater treatment plants.

The technology comes amid the F&B industry’s ongoing attempts at tackling climate change through initiatives like methane-busting feed solutions, methane blockers, feed additives, plant and animal genetics and methane vaccines.

Despite such efforts, GHG emissions have continually increased in recent years, with 2021 and 2022 witnessing the most significant spikes in methane emissions ever recorded, according to Climateworks Foundation and Global Methane Hub.

“We are well on our way toward breaking the 1.5 degree Celsius limit stated in the Paris Agreement. They say we have even already exceeded that limit, globally, for shorter periods,” Matthew Stanley Johnson, professor of chemistry at the University of Copenhagen in Denmark, who led the research, tells Food Ingredients First.

“Methane may be our last best hope to avoid crossing important climate tipping points.” 

The findings — published in the journal Environmental Research Letters — were presented by Johnson virtually at the recently concluded COP28 in Dubai, UAE, and Washington DC, US, at the National Academy of Sciences, which advises the US government on science and technology.

The methane trap
As a preliminary investigation for this study, the researchers traveled around the country measuring how much methane leaks from cattle stalls, wastewater treatment plants and biogas plants.

“Denmark is a pioneer when it comes to producing biogas. But if just a few percent of the methane from this process escapes, it counteracts any climate gains,” says Johnson.

Almost 90% of GHG emissions from agriculture in Denmark come from cattle and swine breeding, Copenhagen Economics analysis suggests.He adds that methane emissions arise from millions of low-concentration point sources like cattle and pig barns. Methane from these sources has been “practically impossible” to concentrate or remove at higher levels. 

“Methane stays in the atmosphere for a decade, much shorter than carbon dioxide,” he says, adding that by stopping its sources, it can be “washed out” of the atmosphere in the near term. 

“A lot of methane emissions can’t be stopped by plugging a leak, such as cow burps and biomass storage and wastewater treatment and garbage dumps. They are diffuse, low-concentration sources. That’s where we come in.”

The researchers have built a reaction chamber that looks like an elongated metal box with heaps of hoses and measuring instruments to remove methane from air. Inside the box, a chain reaction of chemical compounds takes place, breaking down the methane and removing a large portion of the gas from the air.

On Wednesday, a 40 foot shipping container arrived at the University’s Department of Chemistry. It is a “larger prototype” of the reaction chamber that the researchers built in the laboratory and the team will build its system into it for the field test, they told us.

The system is touted to be a “methane cleaner,” which will connect to the ventilation system in a livestock barn.

Are existing methods not enough?
The study warns that despite the urgent need, very few methods can “efficiently” remove methane from waste air with low cost and energy per unit volume.

“There are a lot of technologies for capturing and storing carbon dioxide, but few or none for methane, especially at low concentrations. It’s not because methane isn’t important. It has two-thirds of the climate impact of carbon dioxide and around a hundred times higher global warming effect on a per-mass basis,” he tells us.

The laboratory prototype of the MEPS technology reportedly removes methane by 58% (Image credit: University of Copenhagen).“The chemical properties of methane are very different. With carbon dioxide, you can dissolve it in water and turn it into a salt or a mineral, compress it into a liquid and you can get it to stick to a catalyst.”

In contrast, methane doesn’t dissolve in water or form salts or minerals and bounces off of catalysts.

“Of course, if methane is at high concentration, above 4.4%, it can be burned as fuel. Unfortunately, most methane sources have low concentrations — three-quarters of them have a concentration under 1000 ppm.”

Conversely, by using light and chlorine, the scientists can trigger a reaction and break down the methane “roughly 100 million times faster than in nature,” explains Johnson.

“Stealing” hydrogen atoms 
The researchers use chlorine atoms, which “seek out” methane and steal a hydrogen atom from it, leaving it open for reaction with atmospheric oxygen.

“We trap the product of this reaction, hydrogen chloride, recycle the chlorine and produce a stream of pure hydrogen gas from the hydrogen that came from methane,” says Johnson.

In the scientific study, the scientists proved that their reaction chamber could eliminate 58% of the methane from the air. And, since submitting the study, they claim to have improved the laboratory results to take it up to 88%.

“We found ways to increase the efficiency of using light in our photoreactor. It is a question of making every photon count, and to do that, you need the right gas composition and the right materials,” explains Johnson.

F&B implications
Consumers are waking up to the climate impacts of meat and dairy, flags Johnson. 

Moreover, demands for low-carbon or carbon-free, climate-friendly foods are on an uphill climb.

“The MEPS system can be used right away to cut the GHG emissions of livestock production and this has impacts throughout the value chain from milk to cheese to chocolate and meat production.”

As a novel technique that combats methane emissions, the method is reportedly garnering a positive market reaction.

“The value proposition is very simple: we increase the value of the agricultural product so the system pays for itself,” underscores Johnson.

“We already have strong support from Arla, the largest dairy cooperative in Northern Europe, which is a partner in our project. All indications are that there is a strong demand in the industry.”

By Insha Naureen