Dairy methane removal: Ambient Carbon leverages “table salt” to enhance system efficiency

Tackling greenhouse gas (GHG) emissions is a priority of the European Green Deal, including methane—the second most important GHG contributor to climate change following carbon dioxide, as per the EC. Danish company Ambient Carbon is targeting its reduction with a Methane Eradication Photochemical System (MEPS) that can “dilute” methane sources like dairy cattle, wastewater treatment, waste and biogas.

According to the International Energy Agency, the annual increase in methane concentration from 2020 to 2021 was the highest on record and continued to increase in 2022. In 2023, agriculture accounted for 142 metric tons of methane emissions.

Additionally, methane is 84 times more powerful a GHG than carbon dioxide when measured over a 20 years, and livestock emits approximately 30% of worldwide anthropogenic methane, with dairy cattle generating half of those emissions, states Ambient Carbon.

Food Ingredients First speaks with Matthew Johnson, the company’s co-founder and CSO, to understand the challenges in tackling methane emissions and how the business plans to scale the MEPS technology.

“The US National Academy of Science just released a major report about atmospheric methane, which emphasized the urgent need to bring down methane immediately by methane mitigation (source control), and also explored the options for removing methane directly from the atmosphere.”

MEPS translates into the least amount of power per gram of methane, says Johnson.He adds that while the report states there are currently no technologies to address methane emissions sources with a methane concentration below 1000 ppm, Ambient Carbon’s MEPS “unlocks a long list of methane mitigation sectors.”

“MEPS technology is the number one in the world as far as quantum efficiency for destroying methane, and this translates into the least amount of power per gram of methane. This differential advantage gets larger and larger at lower methane concentrations.”

Tapping table salt

Ambient Carbon’s methane eradication system uses a patented gas-phase photochemical process that combines chlorine atoms and UV light in a reaction chamber.

“We put in salt, activate it with electrolysis and UV light, and that removes the methane. The whole system is outside of the barn, so it doesn’t disturb the cows — cow comfort is the number one concern for these operations,” explains Johson.

However, the team faced technical challenges owing to methane being the least reactive hydrocarbon. “Unlike CO2, it doesn’t want to dissolve in water, form salts or minerals, or stick to catalysts.”

The company’s first system was based on the radical hydroxyl, which led to long treatment times. Ultimately, they designed a system that uses common “table salt (sodium chloride) as the source of chlorine,” he shares.

The company uses table salt as a chlorine source for the methane eradication system.“We work with it at very low concentrations. Using chlorine has been the key to reducing treatment times and increasing system efficiency.”

Supporting methane reduction methods

The dairy industry is leveraging techniques like adding feed additives to cattle feed to reduce enteric methane emissions. Scientists also recommend cover cropping, solid separation and anaerobic digestion for manure management in dairy operations to contain methane emissions.

When asked if MEPS can complement such methods, Johnson says: “Yes, we are complementary. For example, MEPS needs an enclosed or semi-enclosed barn to collect methane, whereas feed additives would work for free-range cattle.”

“One difference is that MEPS is a total solution — we plan to remove virtually all methane from the operation and not just the enteric methane from the cows, but also the methane coming from manure, which is about ¼ of the total.”

“Feed additives are a partial solution, and while they do not address methane from manure, there are potentially other technologies that could do that. Another difference is that we do not interrupt the normal operation of the farm or the cows, we sit outside the barn,” he adds.

Eyeing efficiency and scale

The company is now working on scaling the MEPS system from its current lab and portable test rig to the large-scale prototype it plans to install at Benton Farms in the US and improving the process engineering, such as the photoreactor design and the placement and design of the UV lights,” Johnson shares.

The company is now working to scale the system’s current performance, targeting nearly €190 (US$207.6) per metric ton of CO2e for methane destruction.Meanwhile, it aims to scale the system’s current performance, targeting nearly “€190 (US$207.6) per metric ton of carbon dioxide equivalent for methane destruction.”

“Our cost estimates come in at a few euro cents per liter of low carbon milk, which is right where the dairies (we are working with Arla in Europe) say we need to be.” This includes the treatment system, operating expenses, insurance and end-of-life destruction.

“We believe, with the improvements currently on the drawing board, that we will destroy methane for under €50 (US$54.6) per metric ton of CO2 equivalent by the time we reach commercial production,” concludes Johnson.

The company has received positive market reaction to the technology. As part of the project, Ambient Carbon has a Memorandum of Understanding with Danone North America, which sources milk from Benton Farms.