Sustainable Aviation Fuel (SAF) is a low-carbon alternative to conventional jet fuel, produced from renewable or waste-derived feedstocks. Designed to be used in existing aircraft engines and infrastructure, SAF offers a practical and immediate way to reduce the aviation sector’s carbon footprint—one of the hardest sectors to decarbonize due to its reliance on high-energy-density liquid fuels.
SAF can reduce lifecycle greenhouse gas emissions by up to 80% compared to fossil-based jet fuel, depending on the feedstock and production pathway. It is one of the key levers to help the aviation industry meet global climate targets and transition to more sustainable air travel.
What is SAF?
Sustainable Aviation Fuel refers to jet fuel substitutes produced from non-fossil sources, such as:
- Used cooking oil
- Agricultural residues
- Forestry waste
- Municipal solid waste
- Algae
- CO₂ captured from the atmosphere combined with green hydrogen (e.g. e-Kerosene)
SAF is chemically similar to traditional Jet A-1 fuel and can be blended with it up to 50%, depending on certification standards. The fuel must meet strict technical and safety requirements defined by ASTM International (ASTM D7566) before being approved for use in commercial aircraft.
How is SAF produced?
There are several approved and emerging production pathways for SAF. The most prominent include:
- HEFA (Hydroprocessed Esters and Fatty Acids): The most mature and widely used process, converting waste oils and fats into jet fuel.
- FT-SPK (Fischer-Tropsch Synthetic Paraffinic Kerosene): Converts biomass or waste gases into syngas, which is then processed into liquid hydrocarbons.
- Alcohol-to-Jet (ATJ): Converts ethanol or butanol into jet fuel.
- Power-to-Liquid (PtL): Produces e-SAF by synthesizing captured CO₂ and green hydrogen into hydrocarbons like e-Kerosene.
Each of these pathways is evaluated for sustainability, feedstock availability, and emissions reduction potential.
Why is SAF important?
Aviation accounts for approximately 2-3% of global CO₂ emissions, but its share is expected to grow as demand for air travel increases. While electrification and hydrogen may eventually play a role in decarbonizing short-range flights, long-haul aviation will continue to rely on liquid fuels for the foreseeable future.
SAF provides a drop-in solution that can be adopted immediately, allowing airlines and airports to reduce emissions without waiting for new aircraft designs or infrastructure.
Key use cases include:
- Commercial flights: SAF is already being used in blended form on scheduled flights by major airlines.
- Military and cargo aviation: Offers fuel security and sustainability for non-commercial fleets.
- Airport operations and ground vehicles: SAF can sometimes also be used in supporting infrastructure, depending on the setup.
Benefits of SAF
SAF is widely regarded as one of the most viable short- to medium-term solutions for decarbonizing air travel. Its benefits include:
- Lower carbon emissions: Depending on the feedstock and method, SAF can reduce total lifecycle emissions by 60–80%.
- Compatibility with current systems: SAF can be blended with conventional jet fuel and used without modifying aircraft or fuel infrastructure.
- Improved air quality: SAF burns more cleanly, reducing particulate matter and sulfur emissions.
- Supports circular economy: Many SAF feedstocks are derived from waste or byproducts, contributing to resource efficiency.
- Energy diversification: Reduces reliance on fossil fuels and enhances fuel supply security
Challenges
Despite its advantages, SAF faces several obstacles:
- Limited supply: Current SAF production represents less than 1% of total jet fuel consumption worldwide.
- High cost: SAF is currently 2–4 times more expensive than conventional jet fuel, due to feedstock costs and processing technologies.
- Feedstock availability: Sustainable sourcing of waste or biomass feedstocks must be balanced with food security, land use, and biodiversity considerations.
- Policy and investment needs: Widespread adoption requires regulatory support, incentives, mandates, and significant infrastructure investment.
