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This is no longer an experiment on paper, but a working technology.
California startup Circularity Fuels showed how the manure from a dairy farm can be turned into aviation fuel. The company completed a six-month pilot near Madera in California: gas from a sled tank reactor on a farm with more than 5000 cows was recycled into a stable SAF aviation fuel, suitable for mixing with conventional Jet-A.
The SAF idea is not new. Airlines are looking for fuel with a smaller climatic footprint, because flights are difficult to transfer to batteries: batteries for large aircraft are still too heavy. The problem is different. There is little sustainable aviation fuel in the world, the output covers less than 1% of the demand, and most of the current production depends on limited raw materials like used deep oil.
Circularity Fuels offers another source: agricultural biogas. On dairy farms, manure is often sent to anaerobic reactors, where organics decompose without oxygen and emit a mixture of gases. The pilot used raw biogas of about 65% of methane and 35% carbon dioxide. Usually, before further use, such a flow needs to be cleaned, but the Circularity system worked with gas directly from the reactor.
Methane is important here not only as a raw material for fuel. If it enters the atmosphere, then in a short period it holds heat much stronger than carbon dioxide. Therefore, the capture of farm biogas gives a double effect: the company receives carbon for fuel and at the same time removes the release, which could otherwise enhance the greenhouse effect.
The pilot plant worked on the farm for thousands of hours. First, the electrified bio-forming reactor converted the original mixture of methane and CO2 into a synthesis gas. This is a mixture from which more complex hydrocarbons can then be collected. After that, the compact Fischer-Tropsch reactor transferred the synthesis gas to liquid fuel, suitable for aviation.
The Fisher-Tropsch process has long been known in the chemical industry. Its meaning is simple: liquid hydrocarbons are obtained from gas, close in properties to fuel. For aviation, this is not enough in itself. The final product must pass the quality standard because the fuel falls into existing aircraft and engines. Circularity states that the resulting product complies with ASTM D7566 Annex A1 and can mix with regular Jet-A in a fraction of up to 50%.
The company separately emphasizes the economy of the project. According to its calculations, commercial installations on this technology can cost less than $ 100 000 per barrel per day of installed capacity. This is about five times lower than the capital costs of comparable SAF plants, which are currently being built in Europe. If the assessment is confirmed on an industrial scale, the fuel from the farm biogas will be able to compete with conventional jet fuel is not only for subsidies.
The reason for the possible savings is associated with the size and placement of the installation. Biogas on farms occurs in small distributed streams. To send it to normal processing, you need cleaning, compression, pipelines or transportation. Circularity is betting on modular reactors that can be placed closer to the gas source. The installation processes the raw materials on the spot and does not require expensive infrastructure for pre-cleaning.
During the tests, the reforming unit showed a conversion of methane above 98%, and carbon dioxide above 90%. For a system that works with unprocessed biogas, this is an important indicator. Farm gas usually contains variable impurities and is not like perfectly prepared industrial raw materials. If the technology can withstand such a flow, it has a better chance of working not only on a demonstration platform, but also on real farms.
The climate assessment is even bolder, but it should be analyzed carefully. Internal analysis of the Circularity life cycle gives a carbon intensity of minus 350.7 g of CO2 equivalent to megajoule according to California rules. A negative value does not appear because the aircraft stops throwing CO2 when fuel is burned. The main contribution is given by the preventable release of methane, which could otherwise go into the atmosphere.
For dairy farms, this technology can create a new source of income. There is a biogas on the farm, but not every farm has enough money for complex cleaning and connecting to gas infrastructure. If recycling can be placed next to the dung reactor, the farmer is getting a way to monetize the flow that previously remained underutilized or required additional investments.
For airlines, interest in another. They need more SAF, and not only from raw materials that are no longer enough for everyone. Used vegetable oil, animal fats and other familiar sources are limited. Biogas from farms does not solve the whole problem of aviation fuel, but can add another supply channel, especially in regions with large dairy and agricultural production.
Circularity Fuels plans to begin construction of the first commercial plant in 2027. The company looks at the dairy and agricultural regions of the United States, and is exploring opportunities in Latin America and Europe. The next check will no longer be laboratory and not pilot: the technology needs to prove that it is able to consistently produce aviation fuel at a commercial facility, with real costs, raw materials and requirements of the aviation market.
California startup Circularity Fuels showed how the manure from a dairy farm can be turned into aviation fuel. The company completed a six-month pilot near Madera in California: gas from a sled tank reactor on a farm with more than 5000 cows was recycled into a stable SAF aviation fuel, suitable for mixing with conventional Jet-A.
The SAF idea is not new. Airlines are looking for fuel with a smaller climatic footprint, because flights are difficult to transfer to batteries: batteries for large aircraft are still too heavy. The problem is different. There is little sustainable aviation fuel in the world, the output covers less than 1% of the demand, and most of the current production depends on limited raw materials like used deep oil.
Circularity Fuels offers another source: agricultural biogas. On dairy farms, manure is often sent to anaerobic reactors, where organics decompose without oxygen and emit a mixture of gases. The pilot used raw biogas of about 65% of methane and 35% carbon dioxide. Usually, before further use, such a flow needs to be cleaned, but the Circularity system worked with gas directly from the reactor.
Methane is important here not only as a raw material for fuel. If it enters the atmosphere, then in a short period it holds heat much stronger than carbon dioxide. Therefore, the capture of farm biogas gives a double effect: the company receives carbon for fuel and at the same time removes the release, which could otherwise enhance the greenhouse effect.
The pilot plant worked on the farm for thousands of hours. First, the electrified bio-forming reactor converted the original mixture of methane and CO2 into a synthesis gas. This is a mixture from which more complex hydrocarbons can then be collected. After that, the compact Fischer-Tropsch reactor transferred the synthesis gas to liquid fuel, suitable for aviation.
The Fisher-Tropsch process has long been known in the chemical industry. Its meaning is simple: liquid hydrocarbons are obtained from gas, close in properties to fuel. For aviation, this is not enough in itself. The final product must pass the quality standard because the fuel falls into existing aircraft and engines. Circularity states that the resulting product complies with ASTM D7566 Annex A1 and can mix with regular Jet-A in a fraction of up to 50%.
The company separately emphasizes the economy of the project. According to its calculations, commercial installations on this technology can cost less than $ 100 000 per barrel per day of installed capacity. This is about five times lower than the capital costs of comparable SAF plants, which are currently being built in Europe. If the assessment is confirmed on an industrial scale, the fuel from the farm biogas will be able to compete with conventional jet fuel is not only for subsidies.
The reason for the possible savings is associated with the size and placement of the installation. Biogas on farms occurs in small distributed streams. To send it to normal processing, you need cleaning, compression, pipelines or transportation. Circularity is betting on modular reactors that can be placed closer to the gas source. The installation processes the raw materials on the spot and does not require expensive infrastructure for pre-cleaning.
During the tests, the reforming unit showed a conversion of methane above 98%, and carbon dioxide above 90%. For a system that works with unprocessed biogas, this is an important indicator. Farm gas usually contains variable impurities and is not like perfectly prepared industrial raw materials. If the technology can withstand such a flow, it has a better chance of working not only on a demonstration platform, but also on real farms.
The climate assessment is even bolder, but it should be analyzed carefully. Internal analysis of the Circularity life cycle gives a carbon intensity of minus 350.7 g of CO2 equivalent to megajoule according to California rules. A negative value does not appear because the aircraft stops throwing CO2 when fuel is burned. The main contribution is given by the preventable release of methane, which could otherwise go into the atmosphere.
For dairy farms, this technology can create a new source of income. There is a biogas on the farm, but not every farm has enough money for complex cleaning and connecting to gas infrastructure. If recycling can be placed next to the dung reactor, the farmer is getting a way to monetize the flow that previously remained underutilized or required additional investments.
For airlines, interest in another. They need more SAF, and not only from raw materials that are no longer enough for everyone. Used vegetable oil, animal fats and other familiar sources are limited. Biogas from farms does not solve the whole problem of aviation fuel, but can add another supply channel, especially in regions with large dairy and agricultural production.
Circularity Fuels plans to begin construction of the first commercial plant in 2027. The company looks at the dairy and agricultural regions of the United States, and is exploring opportunities in Latin America and Europe. The next check will no longer be laboratory and not pilot: the technology needs to prove that it is able to consistently produce aviation fuel at a commercial facility, with real costs, raw materials and requirements of the aviation market.
