Key Takeaways
- Circularity Fuels has completed the world's first end-to-end conversion of raw agricultural biogas into sustainable aviation fuel (SAF), following a six-month pilot at a California dairy farm of more than 5,000 head near Madera.
- The fuel meets ASTM D7566 Annex A1 (FT-SPK) specifications and can be blended at up to 50% with conventional Jet-A fuel in commercial aircraft today.
- Internal life-cycle analysis puts the fuel's carbon intensity at -350.7 gCO₂e/MJ under California's regulatory framework — net carbon-negative, with each gallon produced equivalent to removing roughly 100 pounds of CO₂e.
- The system uses two modular, skid-mounted reactors — the Ouro bi-reforming reactor and the Aion Fischer-Tropsch synthesis reactor — designed to operate at individual farm scale without pipeline access or expensive biogas cleanup infrastructure.
- At commercial scale, Circularity Fuels estimates installed capacity at under $100,000 per barrel-per-day — approximately one-fifth the capital cost of SAF plants currently under construction in Europe — with first commercial deployment targeted for 2027.
From Dairy Waste to Jet Fuel: How Circularity Fuels Did It
Circularity Fuels has announced the completion of what it describes as the world's first end-to-end conversion of raw agricultural biogas into sustainable aviation fuel. The six-month pilot drew biogas directly from the manure digester of a California dairy farm, processing it without pre-treatment through an integrated system developed entirely by the company.
The raw biogas — roughly 65% methane and 35% CO₂ — was fed directly into Circularity's on-site system over thousands of operating hours. The resulting fuel meets ASTM D7566 Annex A1 (FT-SPK) specifications, the international standard required for blending with conventional Jet-A in commercial aircraft. It can be blended at up to 50% with Jet-A fuel and used in existing aircraft today with no engine modifications.
Under California's regulatory framework, internal life-cycle modelling puts the fuel's carbon intensity at -350.7 gCO₂e/MJ — firmly net carbon-negative. The negative figure is driven by avoided methane emissions: by consuming gas that would otherwise be vented or flared, each gallon produced is climate-equivalent to removing roughly 100 pounds of CO₂e from the atmosphere.
The Ouro and Aion Reactors
Circularity's system is built around two modular, skid-mounted reactors designed for the small, distributed scales at which agricultural biogas is actually produced.
The Ouro bi-reforming reactor is an electrified unit that achieved more than 98% methane conversion and more than 90% CO₂ conversion in a single step. High CO₂ content has historically been the main barrier to economical biogas processing — the Ouro reactor addresses this directly. The Aion Fischer-Tropsch synthesis reactor then converts the reformed gas into finished jet fuel on-site.
Because both reactors are modular and designed for farm-scale deployment, the system does not require expensive biogas cleanup infrastructure or proximity to a gas pipeline — removing two of the most significant barriers that have prevented dairy operators from monetizing their biogas output.
Capital Costs That Compete with Fossil Jet Fuel
The pilot puts commercial SAF production within reach at under $100,000 per barrel-per-day of installed capacity at commercial scale — approximately one-fifth the capital cost of SAF plants currently under construction in Europe. That cost structure allows Circularity Fuels to sell its jet fuel at fossil parity even from a first-of-a-kind commercial plant.
The fuel qualifies for both federal and state biofuel incentive programmes, including the EPA's Renewable Fuel Standard and California's Low Carbon Fuel Standard (LCFS) — the same policy mechanisms that enabled renewable natural gas, ethanol, and biodiesel to reach commercial scale. For those following how agricultural waste streams are being converted into commercial energy products, this pilot represents one of the more technically complete proofs of concept to date.
“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. We've now done that. The full stack works end-to-end on real feedstock from a real dairy farm, and the economics put commercial SAF from dairy waste within reach of fossil jet fuel.” — Dr. Stephen Beaton, Founder and CEO, Circularity Fuels
Why Agricultural Biogas Is the Right Feedstock
Agricultural biogas is among the lowest-cost feedstocks available for SAF production, largely because most of it currently goes to waste. The global waste biogas resource is theoretically large enough to supply the entire global jet fuel market, yet most dairy and livestock operations today vent or flare their biogas because conventional cleanup and off-take infrastructure is prohibitively expensive.
Current SAF production meets less than 1% of global aviation fuel demand and is dominated by used cooking oil — a feedstock with limited scalability and significant import dependency. Circularity Fuels targets an abundant, domestic, and largely untapped resource instead.
Circularity Fuels Eyes Commercial Deployment from 2027
With its integrated technology stack validated in the field, Circularity Fuels is preparing for its first commercial-scale build. The company expects to break ground on its first commercial site in 2027, targeting agricultural biogas resources across the United States, Latin America, and Europe.
