Circularity Fuels Produces Jet Fuel From Dairy Manure Biogas in California Trial, Raises $7 Million
Why It MattersFarm-based biogas conversion widens the feedstock base for sustainable aviation fuel, though the 75-barrel-a-day commercial design shows the approach is still far from meeting airline demand.
Circularity Fuels, a San Francisco Bay area startup, has converted gas from decomposing cow manure into jet fuel at a dairy farm near Madera in California's San Joaquin Valley. The company says its six-month trial was the first to take raw biogas from a dairy's leftover manure and produce synthetic kerosene that meets aviation standards for blending with conventional jet fuel. The dairy has about 5,000 head of cattle. Its digester releases methane and carbon dioxide as manure breaks down, and Circularity's equipment uses both gases, drawing biogas directly without first removing the carbon dioxide. An electrically powered reactor converts the gases into synthesis gas, a mixture of hydrogen and carbon monoxide, and a second reactor uses the Fischer-Tropsch process to turn that into liquid hydrocarbons. Both reactors mount on skids.
Circularity reported the results in June 2026, saying the fuel met ASTM D7566 Annex A1, the specification for synthetic kerosene made using the Fischer-Tropsch process. Fuel produced under that specification can account for up to 50% of a blend with conventional jet fuel. The company estimates that capturing methane that would otherwise escape from cow manure prevents more warming than making and burning the jet fuel causes, which by its calculation makes the fuel carbon-negative.
The company has recently raised $7 million in seed funding, led by Trucks Venture Capital and DCVC, with Sum Ventures and Automotive Ventures also participating. The money will go toward a demonstration plant that can produce the fuel daily and the design of a first commercial plant with a capacity of 75 barrels a day, a little over 3,000 US gallons. Circularity has raised about $17 million to date, including nearly $7 million in grants, and says the US Department of Agriculture has advanced its application for a federal loan guarantee to the second stage. Over the next 18 months, it intends to run the demonstration plant, finish the commercial plant design and secure fuel purchase agreements with airlines before breaking ground on a production facility.
