The Rise of Sustainable Aviation Fuel

What Is Sustainable Aviation Fuel?

Sustainable aviation fuel (SAF) is a liquid fuel used to power aircraft that is produced from renewable or waste-based feedstocks rather than petroleum. Chemically, SAF is engineered to be a "drop-in" fuel, meaning it can be blended with conventional Jet A or Jet A-1 fuel and used in existing aircraft engines and airport fueling infrastructure without modification. Under current international standards, SAF blends are certified up to 50% with conventional jet fuel, depending on the production pathway used.

Common Feedstocks

SAF can be produced from a range of sustainable feedstocks, including:

• Used cooking oil and waste animal fats
• Municipal solid waste
• Agricultural and forestry residues
• Non-food energy crops
• Captured carbon combined with hydrogen (power-to-liquid pathways)

The diversity of feedstocks is important because it reduces competition with food production and allows SAF production to be adapted to regional resource availability.

Why SAF Matters for Decarbonization

Aviation is one of the harder sectors to decarbonize because long-haul flights require energy-dense liquid fuels that batteries and current hydrogen technology cannot yet practically deliver at scale. SAF addresses this gap by offering a lower-carbon alternative that works within existing aircraft and fuel infrastructure.

Lifecycle Emissions Reduction

SAF's environmental benefit comes primarily from its lifecycle carbon footprint rather than tailpipe emissions at the point of combustion. Because SAF is derived from biomass or waste that previously absorbed carbon dioxide during its growth or was otherwise destined for disposal, its net lifecycle emissions are lower than those of fossil-derived jet fuel. The degree of reduction depends heavily on the feedstock and production process used, but SAF is broadly recognized by aviation and climate bodies as one of the few near-term levers available for reducing aviation's carbon footprint.

Industry and Policy Alignment

The International Air Transport Association (IATA) has identified SAF as the largest single contributor toward the industry's stated goal of achieving net-zero carbon emissions by 2050. Governments have responded with policy support: the European Union's ReFuelEU Aviation regulation mandates increasing minimum shares of SAF at EU airports starting in 2025, with the requirement rising over subsequent decades. In the United States, the SAF Grand Challenge, a joint initiative of several federal agencies, has set targets for scaling domestic SAF production through the 2030s and beyond.

How SAF Is Produced

Several certified production pathways exist under ASTM International's D7566 standard, which governs synthetic aviation fuel blends. The most widely deployed pathway today is Hydroprocessed Esters and Fatty Acids (HEFA), which converts fats, oils, and greases into jet fuel through hydrogenation. Other approved pathways include Fischer-Tropsch synthesis, which converts syngas derived from biomass or waste into liquid hydrocarbons, and Alcohol-to-Jet (ATJ), which converts alcohols such as ethanol into jet fuel.

Certification and Safety

Before any SAF pathway can be used commercially, it must undergo rigorous testing and certification to ensure it meets the same performance and safety specifications as conventional jet fuel. This certification process, overseen by bodies such as ASTM International, is what allows SAF to be blended and used in commercial aircraft without requiring engine or airframe modifications.

Current Challenges Facing SAF Adoption

Despite growing momentum, SAF still represents a very small fraction of total global jet fuel consumption. Several structural challenges continue to limit widespread adoption.

Cost

SAF is generally more expensive to produce than conventional jet fuel, largely due to feedstock costs, limited production scale, and the capital-intensive nature of refining facilities. This price premium is a significant barrier for airlines operating on thin margins.

Feedstock and Production Scale

Available volumes of waste oils and fats are finite, and scaling up SAF production to meaningfully offset global jet fuel demand will require diversifying into additional feedstocks, including agricultural residues and synthetic fuels produced from captured carbon and renewable hydrogen. Building new refining capacity also requires significant investment and lead time.

Policy and Investment Certainty

Long-term offtake agreements, government incentives, and clear regulatory frameworks are widely viewed as essential to giving fuel producers the investment certainty needed to build new SAF production facilities at scale.

The Path Forward

Airlines, fuel producers, aircraft manufacturers, and governments are increasingly aligning around SAF as a central pillar of aviation's decarbonization strategy. Numerous airlines have signed offtake agreements with SAF producers, and aircraft manufacturers such as Boeing and Airbus have stated that their aircraft are designed to be compatible with increasing SAF blend ratios, with an industry goal of certifying aircraft and engines for 100% SAF use.

Continued progress will depend on scaling production capacity, diversifying feedstocks, reducing costs through technological improvement, and maintaining supportive policy frameworks across major aviation markets. While SAF alone will not fully decarbonize aviation, it remains one of the most immediately actionable tools available to the industry as it works toward its long-term climate goals.

Conclusion

Sustainable aviation fuel represents a practical bridge between today's fossil-fuel-dependent aviation sector and a lower-carbon future. As production scales and policy frameworks mature, SAF is expected to play an increasingly central role in how the aviation industry addresses its climate impact over the coming decades.