A California technology company says it has successfully converted raw biogas from a dairy manure digester into sustainable aviation fuel (SAF), creating what could become a new market for methane produced on dairy farms.
Circularity Fuels recently announced it completed a six-month pilot project at a California dairy near Madera, converting biogas from manure into jet fuel that meets industry specifications for use in commercial aircraft. The company says the project is the first to produce sustainable aviation fuel using raw biogas generated on a farm.
The pilot was conducted on a dairy with more than 5,000 head, where biogas from a digester was fed directly into Circularity’s processing system. The technology converted the gas into finished jet fuel without the extensive gas cleanup typically required for many renewable energy projects.
A New Pathway for Dairy Digesters?
For dairy farmers, the development could create another potential market for methane generated from manure.
Today, most digesters generate renewable natural gas, but that can require expensive gas-cleaning equipment and pipeline access. Circularity says its system can convert raw biogas directly into jet fuel, creating another potential use for methane produced on dairy farms.
The company’s process combines two reactors that convert biogas into synthesis gas and then into liquid fuel. According to Circularity, the pilot achieved more than 98% methane conversion and more than 90% carbon dioxide conversion.
“The hard part of this industry was never designing a theoretical plant that could make SAF. It was proving you could do it continuously, from real biogas, at a cost that pencils,” says Stephen Beaton, founder and CEO of Circularity Fuels. “We’ve now done that.”
Craig Hartman of Hartman Engineering, which has worked on agricultural biogas projects for years, says the technology could expand opportunities for dairy operators.
“For two decades, we’ve watched dairies flare or vent biogas because the only off-take options required millions in cleanup equipment and a pipeline next door,” Hartman says. “Circularity is the first team I’ve seen take raw biogas straight from a digester and turn it into finished jet fuel on-site.”
Addressing SAF Supply Challenges
Interest in sustainable aviation fuel continues to grow as airlines look for lower-carbon alternatives to conventional jet fuel. However, SAF production currently accounts for less than 1% of global jet fuel demand, according to Circularity.
The company says much of today’s SAF production relies on used cooking oil and other waste fats. Agricultural biogas, by comparison, is widely available and often underutilized.
According to Circularity, the resulting fuel qualifies as Fischer-Tropsch synthetic paraffinic kerosene (FT-SPK), an approved SAF pathway that can be blended at up to 50% with conventional Jet-A fuel. The company also says the fuel could qualify for federal and state renewable fuel incentives, including the Renewable Fuel Standard and California’s Low Carbon Fuel Standard.
Carbon-Negative Potential
Methane is a significantly more potent greenhouse gas than carbon dioxide. By capturing the gas that would otherwise be released into the atmosphere and converting it into fuel, Circularity says the process can achieve a carbon-negative score under California’s life-cycle accounting framework.
Based on internal modeling, Circularity estimates the fuel’s carbon intensity at -350.7 gCO₂e/MJ. The company says each gallon of fuel produced is equivalent to removing roughly 100 lbs. of carbon dioxide-equivalent emissions from the atmosphere.
Looking Ahead
With the pilot completed, Circularity Fuels is now preparing for its first commercial-scale deployment.
The company says its technology can be built at a fraction of the cost of many sustainable aviation fuel facilities currently under development and could eventually produce SAF at a cost competitive with conventional jet fuel. Circularity expects to break ground on its first commercial project in 2027 and plans to target agricultural biogas resources across the United States, Latin America and Europe.
If the technology proves successful at commercial scale, it could provide dairy digesters with another outlet for methane generated from manure while helping meet growing demand for sustainable aviation fuel.
