An aviation biofuel, also called bio-jet fuel, sustainable aviation fuel (SAF), or bio-aviation fuel (BAF), is a type of fuel used to power airplanes. The International Air Transport Association (IATA) sees it as a key way to reduce the environmental impact of flying. Aviation biofuel helps reduce carbon emissions from medium and long-haul flights, which produce the most pollution. Synthetic paraffinic kerosene (SPK) is a type of fuel that replaces traditional kerosene jet fuel. SPK is often, but not always, made from plant or animal materials.

Biofuels are fuels made from plants, animals, or waste. Depending on the source, they can reduce carbon dioxide (CO₂) emissions by 20–98% compared to regular jet fuel. The first flight using a mix of biofuel and regular fuel happened in 2008. In 2011, flights using 50% biofuel were allowed on commercial airplanes. In 2023, 600 million liters of SAF were produced, which was 0.2% of all global jet fuel use. By 2024, SAF production was expected to reach 1.3 billion liters (1 million tonnes), or 0.3% of global jet fuel use and 11% of global renewable fuel production. This increase happened because some major U.S. production facilities delayed their plans until 2025, as they had originally aimed to produce 1.9 billion liters.

Aviation biofuel can be made from plants or animals, such as Jatropha, algae, waste oils, palm oil, Babassu, and Camelina (bio-SPK). It can also be made from solid plant material using a process called pyrolysis and then refined with a Fischer–Tropsch process (FT-SPK). Another method uses an alcohol-to-jet (ATJ) process from waste fermentation. A solar reactor and synthetic biology are also used to create biofuel. Small engines can be modified to burn ethanol.

Sustainable biofuels are an alternative to electrofuels. SAF is checked by third-party organizations to ensure it is produced sustainably.

SAF technology faces challenges because of limited supplies of materials needed to make it. Oils and fats called hydrotreated esters and fatty acids (Hefa), which are important for SAF, are in short supply as demand grows. Although new technology called e-fuels, which combines waste CO₂ with clean hydrogen, may help, it is still being developed and is expensive. To solve these problems, SAF developers are looking for easier-to-find materials, such as wood and waste from farms or cities, to create cleaner and more efficient jet fuel.

History

The first flight using blended biofuel happened in 2008. Virgin Atlantic used this fuel to operate a commercial flight, using materials like algae. Airlines that represent more than 15% of the industry created the Sustainable Aviation Fuel Users Group, with help from groups like the Natural Resources Defense Council and The Roundtable For Sustainable Biofuels by 2008. These airlines promised to develop sustainable biofuels for aviation. In 2008, Boeing was co-chair of the Algal Biomass Organization, along with airlines and a company called UOP LLC (Honeywell).

In 2009, the IATA committed to achieving carbon-neutral growth by 2020 and to cutting carbon emissions in half by 2050.

In 2010, Boeing announced a goal to use 1% of global aviation fuel from biofuels by 2015.

By June 2011, a new standard called ASTM D7566 allowed commercial airlines to mix up to 50% biofuels with regular jet fuel. ASTM International checks the safety and performance of jet fuel used in flights. After many years of testing by aircraft makers, engine companies, and oil firms, biofuels were approved for use in commercial flights. Some airlines then tested biofuels on regular flights. By July 2020, seven updates to D7566 were published, including these biofuel types:

• Fischer-Tropsch Synthetic Paraffinic Kerosene (FT-SPK, 2009)
• Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene (HEFA-SPK, 2011)
• usHydroprocessed Fermented Sugars to Synthetic Isoparaffins (HFS-SIP, 2014)
• Fischer-Tropsch Synthetic Paraffinic Kerosene with Aromatics (FT-SPK/A, 2015)
• Alcohol to Jet Synthetic Paraffinic Kerosene (ATJ-SPK, 2016)
• Catalytic Hydrothermolysis Synthesized Kerosene (CH-SK, or CHJ; 2020).

In December 2011, the FAA gave $7.7 million to eight companies to develop sustainable fuels, especially from alcohols, sugars, biomass, and organic materials like pyrolysis oils, through its CAAFI and CLEEN programs.

A company called Solena went bankrupt in 2015.

By 2015, scientists were studying how to grow fatty acid methyl esters and alkenones from algae called Isochrysis.

By 2016, Thomas Brueck of Munich TU predicted that growing algae could meet 3–5% of jet fuel needs by 2050.

In fall 2016, the International Civil Aviation Organization announced plans to use sustainable aviation fuels.

Many companies received hundreds of millions of dollars in funding from 2005 to 2012 to make fuel from algae. Some claimed they could produce fuel at a low cost by 2012 and make 1 billion U.S. gallons by 2012–2014. However, by 2017, most of these companies had stopped working on this or changed their goals.

In 2019, only 0.1% of fuel used was sustainable aviation fuel (SAF). The IATA supported SAF, aiming for 2% of fuel to be SAF by 2025, which would be 1.8 billion U.S. gallons.

In early 2021, Boeing’s CEO, Dave Calhoun, said sustainable aviation fuels are the only way to reduce carbon emissions between now and 2050. In May 2021, the IATA set a goal for the aviation industry to reach net-zero carbon emissions by 2050, with SAF as a key part of this plan.

The 2022 Inflation Reduction Act created the Fueling Aviation's Sustainable Transition (FAST) Grant Program. This program gives $244.5 million in grants for activities related to SAF, such as production, transportation, blending, and storage. In November 2022, sustainable aviation fuels were discussed at COP26.

As of 2023, 90% of biofuel was made from oilseed and sugarcane, which are grown specifically for this purpose.

The European Union requires that 6% of all aviation fuel sales be biofuel by 2035 and 70% of sales be biofuel by 2050.

Production

Jet fuel is a mixture of different hydrocarbons. The type of mixture depends on product needs, such as freezing point and smoke point. Jet fuels are sometimes classified as kerosene or naphtha-type. Kerosene-type fuels include Jet A, Jet A-1, JP-5, and JP-8. Naphtha-type jet fuels, sometimes called "wide-cut" jet fuel, include Jet B and JP-4.

"Drop-in" biofuels are biofuels that can be used in place of regular fuels. Creating "drop-in" jet fuel from plant-based sources is approved by ASTM through two methods. ASTM has found it safe to mix 50% synthetic paraffinic kerosene (SPK) into regular jet fuels. Tests showed that blending SPK in much higher amounts is also possible.

Several research projects and companies have developed technologies to produce synthetic hydrocarbons and sustainable aviation fuels (SAF).

The SUN-to-LIQUID project (2016-2019) was a European Union-funded research initiative that demonstrated the production of sustainable aviation fuel directly from sunlight, water, and carbon dioxide. The project used a process involving a solar reactor to create synthesis gas (syngas), which was then turned into jet fuel using Fischer-Tropsch synthesis. On June 13, 2019, researchers in Spain successfully completed the full production chain, a major step in solar fuel technology. The project included partners from seven European countries and Switzerland, led by Bauhaus Luftfahrt, and received support from the Swiss State Secretariat for Education, Research, and Innovation. While the project proved that producing drop-in aviation fuel from renewable sources is technically possible without using agricultural land, the technology was still in early stages and needed more work to improve scalability and cost-effectiveness.

Alder Fuels developed a method to convert lignocellulosic biomass, such as forestry and agricultural waste, into a hydrocarbon-rich product called "greencrude" through pyrolysis. This greencrude can then be processed in existing petroleum refineries to create drop-in aviation and transportation fuels. The process uses waste materials that do not compete with food production, solving a sustainability issue linked to earlier biofuels.

Universal Fuel Technologies created Flexiforming technology, a chemical process that turns various materials, including byproducts from renewable fuel production, into sustainable aviation fuel. The technology can handle multiple types of biomass inputs through one process.

Arcadia eFuels built a power-to-liquid facility in Denmark that uses renewable electricity to split water into hydrogen and oxygen through electrolysis. The hydrogen is then combined with captured carbon dioxide to create synthesis gas (syngas), which is converted into jet fuel using Fischer-Tropsch or similar methods.

Small piston engines can be modified to burn ethanol. Swift Fuel, a biofuel alternative to avgas, was approved as a test fuel by ASTM International in December 2009.

Nitrile-based rubber materials expand when exposed to aromatic compounds in regular petroleum fuel. Pure biofuels without petroleum or paraffin-based additives may cause rubber seals and hoses to shrink. Synthetic rubber alternatives, such as Viton, are available and are not affected by biofuels.

The United States Air Force discovered harmful bacteria and fungi in their biofueled aircraft and used pasteurization to clean them.

As of May 2025, SAF is generally required to be mixed with fossil fuel because jet fuel needs certain chemicals, such as cycloalkanes and aromatics, which are less common in SAF. SAF also contains more n-alkanes and isoalkanes, which are more prevalent in SAF than in regular jet fuel.

Economics

In 2019, the International Energy Agency predicted that sustainable aviation fuel (SAF) production would increase from 18 to 75 billion liters between 2025 and 2040. This growth would mean SAF would make up 5% to 19% of all aviation fuel during that time. In 2019, fossil jet fuel cost between $0.30 and $0.60 per liter when crude oil prices were between $50 and $100 per barrel. Aviation biofuel, however, cost between $0.70 and $1.60 per liter and required crude oil prices of $110 to $260 per barrel to break even. As of 2024, SAF accounts for only 0.3% of global aviation fuel.

In 2020, aviation biofuel was more expensive than fossil jet fuel when considering taxes and subsidies at that time.

According to a 2021 analysis, the break-even cost for VFA-SAF was $2.50 per US gallon ($0.66 per liter). This calculation included credits and incentives available at the time, such as California’s Low Carbon Fuel Standard (LCFS) credits and the US Environmental Protection Agency (EPA) Renewable Fuel Standard incentives.

Sustainable aviation fuels

Sustainable biofuels do not use food crops, the best farmland, or fresh water. Sustainable aviation fuel (SAF) is checked by independent organizations, such as the Roundtable on Sustainable Biofuels.

As of 2022, about 450,000 flights had used sustainable fuels as part of their fuel mix. However, these fuels cost about three times more than traditional fossil jet fuel or kerosene. In 2023, SAFs made up less than 0.1% of all aviation fuel used. In 2024, Alaska Airlines used the most SAF among U.S. airlines, with SAF making up 0.68% of its fuel. Other major airlines, such as United, Delta, and JetBlue, used SAF in about 0.3% of their fuel.

A SAF sustainability certification means the product meets standards for environmental, social, and economic factors. In some emission rules, like the European Union Emissions Trading Scheme (EUTS), certified SAF may not need to pay for carbon emissions. This helps make SAF more economically competitive compared to fossil fuels.

The first group to create a sustainable biofuel certification system was the Roundtable on Sustainable Biomaterials (RSB), an organization based in Europe. Airlines and other groups in the Sustainable Aviation Fuel Users Group (SAFUG) agreed to support RSB as their main certification provider.

Some SAF producers used RIN pathways under the U.S. renewable fuel standard. These RINs can act as a form of certification if they are Q-RINs.

As more carbon rules are created, some biofuels may be exempt from compliance costs if they show they are sustainable. For example, in the EUTS, SAFUG proposed that only fuels certified by RSB or similar groups would be exempt. SAFUG was started in 2008 by airlines interested in SAF, with support from Boeing Commercial Airplanes. These airlines represented more than 15% of the industry and promised to work toward using SAF.

Besides SAF certification, the quality of aviation biofuel producers and their products can be checked by groups like Richard Branson’s Carbon War Room or the Renewable Jet Fuels initiative. These groups work with companies such as LanzaTech, SG Biofuels, AltAir, Solazyme, and Sapphire.

Candelaria Bergero of the University of California’s Earth System Science Department, along with her co-authors, said that challenges to producing more sustainable fuel include high technology costs and inefficient processes. Large-scale production could also harm food security and land use.

By 2019, Virgin Australia had used Gevo’s alcohol-to-jet fuel for over 700 flights and more than one million kilometers, both domestically and internationally. Virgin Atlantic worked with LanzaTech to use fuel made from steel mill waste gases. British Airways aimed to make jet fuel from household waste with Velocys. United Airlines committed to using 900 million U.S. gallons of SAF from Fulcrum BioEnergy over 10 years, after investing $30 million in 2015.

Starting in 2020, Qantas planned to use a 50/50 mix of SG Preston’s biofuel on flights between Los Angeles and Australia. SG Preston also planned to supply fuel to JetBlue over 10 years. Neste, based in Finland, planned to increase its renewable fuel production capacity from 2.7 to 3.0 million tons per year by 2020, and to expand its Singapore capacity to 4.5 million tons by 2022 after investing €1.4 billion.

By 2020, International Airlines Group invested $400 million to create SAF from waste using Velocys.

United Airlines has used SAF at airports worldwide, including Amsterdam in 2022, San Francisco and London in 2023, and Chicago O’Hare and Los Angeles in 2024.

In March 2024, JetBlue began regularly using SAF at John F. Kennedy International Airport in the Northeastern United States. Southwest Airlines started using sustainable jet fuel at Chicago Midway International Airport in October 2024.

Fuel supplier Avfuel expanded its SAF offerings in Texas in November 2025 through its partner Million Air at Austin-Bergstrom International Airport (AUS). Earlier in 2025, Avfuel and Million Air had already provided SAF at an FBO at Albany International Airport (ALB) in New York.

Environmental impact

Plants take in carbon dioxide as they grow, so biofuels made from plants release the same amount of greenhouse gases that the plants absorbed. However, making, processing, and transporting biofuels also release greenhouse gases, which reduces the overall benefit. Biofuels that save the most emissions are those made from photosynthetic algae (98% savings), though this technology is not yet fully developed, and those made from non-food crops and forest waste (91–95% savings).

Jatropha oil, a non-food oil used as a biofuel, reduces CO₂ emissions by 50–80% compared to Jet-A1, a kerosene-based fuel. Jatropha plants grow well on land that is not ideal for other crops and produce good yields there. A study on jatropha found that using land previously used for farming and grazing could reduce greenhouse gas emissions by up to 85%, while using land from natural woodlands could increase emissions by up to 60%.

Palm oil production is limited by limited land availability, and expanding it into forests harms biodiversity and causes emissions from changing land use. Neste Corporation uses waste oil from food-grade palm oil production, used cooking oil from fryers, and animal fats to make its renewable products. Neste’s sustainable aviation fuel is used by Lufthansa, and Air France and KLM announced goals to use 2.4 million tonnes of sustainable aviation fuel by 2030, sourced from Neste, TotalEnergies, and DG Fuels.

Aviation fuel made from wet waste, such as landfill waste, wastewater sludge, agricultural waste, and fats, offers environmental benefits. Wet waste can be turned into volatile fatty acids, which are then upgraded into sustainable aviation fuel. This waste is low-cost and plentiful, with the potential to replace 20% of U.S. fossil jet fuel. Using wet waste reduces the need to grow crops for fuel, which uses energy and increases emissions. Diverting wet waste from landfills could eliminate 17% of U.S. methane emissions. This fuel’s carbon footprint is 165% lower than fossil fuel. This technology is still new, but companies like Alder Renewables, BioVeritas, and ChainCraft are working to develop it.

NASA found that mixing 50% biofuel with regular aviation fuel can reduce particulate emissions from air travel by 50–70%. Biofuels do not contain sulfur, so they do not release sulfur dioxide. However, some production methods, like pyrolysis, can create sulfur compounds and other pollutants, such as hydrogen sulfide, hydrogen cyanide, ammonia, and nitrogen dioxide. Other production methods may avoid these emissions.

Making aviation biofuel on a large scale requires significant land, which is a challenge for the industry. Possible solutions include algae farms, which produce more biofuel per area than crops. In 2008, Lufthansa and Virgin Atlantic tested algae as a biofuel source. By 2015, research was underway to use fatty acid methyl esters and alkenones from algae called Isochrysis as a possible jet fuel ingredient.

Technological pathways and economic challenges

To help reduce greenhouse gas emissions globally, the aviation industry is focusing on using Sustainable Aviation Fuels (SAF). In countries with plenty of plant material, such as Brazil, the main methods for reducing carbon emissions are Hydroprocessed Esters and Fatty Acids (HEFA) and Alcohol-to-Jet (AtJ).

Using vegetable oils to make aviation fuel has been studied for many years. A study by Dunn in 2001 showed that these oils could be used as a source for jet fuel, which forms the basis of the modern HEFA method. However, cost has been a big challenge. Earlier research by Lander and Reif in 1986 noted that making jet fuel from alternative sources would require more money than traditional petroleum refining methods.

Today, experts believe that to solve these cost issues, SAF production should be part of biorefineries that also make other renewable chemicals. This approach can create more income sources.

Currently, less than 1% of all liquid biofuels worldwide are used for aviation, and biojet fuel powers less than 0.5% of all flights. Most biofuels are used for cars and trucks. Even if all biofuel production were used for aviation, it would still meet only about one-third of the industry’s needs.