22 December 2023 — Scientists in Denmark have designed a methane elimination photochemical system (MEPS) that uses light and chlorine to remove low concentrations of methane from the air. With a removal efficiency of 58% and a flow rate of 30 liters per minute, the technique is said to remove greenhouse gases (GHG) from livestock and biogas production and wastewater treatment plants.
The technology comes amid ongoing efforts by the F&B industry to tackle climate change through initiatives such as methane breakdown feed solutions, methane inhibitors, feed additives, plant and animal genetics and methane vaccines.
Despite such efforts, GHG emissions have continued to rise in recent years, with 2021 and 2022 seeing the most significant spikes in methane emissions ever recorded, according to the Climateworks Foundation and the Global Methane Hub.
„We’re well on our way to beating the 1.5°C limit set out in the Paris Agreement. They say we’ve already crossed that limit globally,” says Matthew Stanley Johnson, a chemistry professor at the University of Copenhagen in Denmark who led the research. First the food items.
„Methane may be our last hope to avoid crossing critical climate tipping points.”
The Findings – Published in Magazine Environmental Research Letters — Presented by Johnson, who advises the US government on science and technology, at the National Academy of Sciences at the recently concluded COP28 in Dubai, UAE and Washington DC, US.
As a preliminary investigation for the study, researchers traveled across the country to see how much methane was leaking from livestock barns, wastewater treatment plants and biogas plants.
“Denmark is a pioneer in the production of biogas. But if only a few percent of methane escapes from this process, it counteracts any climate gains,” says Johnson.
Methane emissions arise from millions of low-concentration point sources, such as cattle and pig sheds, he adds. It is „practically impossible” to concentrate or remove large amounts of methane from these sources.
„Methane has been in the atmosphere for a decade, much less than carbon dioxide,” he says, adding that by stopping its sources, it could quickly be „washed” out of the atmosphere.
„A lot of methane emissions can’t be stopped by capping leaks like cow burps and biomass storage and wastewater treatment and landfills. Those are diffuse, low-concentration sources. We’re coming in.”
The researchers built a reaction chamber, which is like a long metal box with tubes and measuring instruments to remove methane from the air. Inside the box, a chain reaction of chemical compounds takes place, breaking down the methane and removing most of the gas from the air.
On Wednesday, the 40-foot shipping container arrived at the university’s chemistry department. It’s a „large prototype” of the reaction chamber that the researchers have built in the lab and they told us the team will develop the system for field testing.
The system is said to be a „methane cleaner” that will be connected to the ventilation system in the cattle shed.
Are existing methods insufficient?
Despite the urgent need, the study warns that very few methods can „efficiently” remove methane from waste air at low cost and with energy per unit volume.
„There are lots of technologies for capturing and storing carbon dioxide, but few or none for methane, especially at low concentrations. Not because methane is unimportant. It has about two-thirds the climate impact of carbon dioxide and about a hundred times the global warming effect on a mass basis,” he said. He tells us.
„The chemical properties of methane are very different. With carbon dioxide, you can dissolve it in water and turn it into a salt or mineral, compress it into a liquid and stick it in a catalyst.
In contrast, methane does not dissolve in water or form salts or minerals and leach out of the catalysts.
“Of course, methane can be burned as a fuel at high concentrations, above 4.4%. Unfortunately, most methane sources have low concentrations—three-quarters of them have concentrations below 1000 ppm.
Instead, by using light and chlorine, scientists can trigger a reaction and break down the methane „about 100 million times faster than naturally,” Johnson explains.
„Stealing” hydrogen atoms
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 make pure hydrogen gas from the hydrogen that came from the methane,” Johnson says.
In a scientific study, scientists demonstrated that their reactor could remove 58% of methane from chamber air. And since submitting the study, they claim to have improved lab results to take them up to 88%.
„We found ways to increase the efficiency of using light in our photoreactor. It’s a question of making each photon count, and to do that, you need the right gas mixture and the right materials,” Johnson explains.
Johnson said consumers are waking up to the climate impacts of meat and dairy production.
Also, demands for low-carbon or no-carbon, climate-friendly foods are on the upswing.
„The MEPS system can be immediately applied to reduce the GHG emissions of livestock production, and this has an impact throughout the value chain, from milk to cheese to chocolate and meat production.”
As a new technique to combat methane emissions, this method is receiving a positive market reaction.
„The value proposition is very simple: we increase the value of agricultural production, so the system pays for itself,” Johnson underlines.
„We already have strong support from Northern Europe’s largest dairy cooperative, Arla, who is a partner in our project. All signs point to strong demand in the industry.
By Insha Navreen
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„Oddany rozwiązywacz problemów. Przyjazny hipsterom praktykant bekonu. Miłośnik kawy. Nieuleczalny introwertyk. Student.