Aviation accounts for about 2.5 percent of global CO2 emissions. Sustainable aviation fuel (SAF) is the primary decarbonisation path for the next two decades. This guide covers what SAF is, how it is made, and where the industry actually stands.
What SAF is
SAF is a drop in replacement for conventional jet fuel produced from renewable feedstocks or waste materials. Chemically equivalent to petroleum jet fuel, blendable with fossil jet fuel, and compatible with existing aircraft and airport infrastructure. Certified under ASTM D7566 standard.
Production pathways
| Pathway | Feedstock |
|---|---|
| HEFA (Hydroprocessed Esters and Fatty Acids) | Used cooking oil, animal fats, waste vegetable oils |
| Alcohol to Jet (ATJ) | Ethanol from corn, sugar, cellulose |
| Fischer Tropsch (FT) | Syngas from biomass gasification |
| Power to Liquid (PtL) | Green hydrogen plus captured CO2 |
| Direct Sugar to Hydrocarbons | Microbial fermentation from sugars |
| Catalytic hydrothermolysis | Biomass processing at high temperature |
HEFA dominates current production
HEFA (from used cooking oil and animal fats) produces roughly 95 percent of current SAF. Neste is the largest producer. Feedstock supply constraint limits growth. Other pathways scaling to meet future demand.
Current scale
Emissions reduction
SAF lifecycle emissions typically 50 to 80 percent lower than conventional jet fuel, depending on feedstock and pathway. Power to Liquid can approach 90+ percent reduction if renewable powered.
Regulatory mandates
| Programme | Requirement |
|---|---|
| EU ReFuelEU | 2% by 2025 rising to 70% by 2050 |
| UK Jet Zero | 10% by 2030 |
| US SAF Grand Challenge | 3 billion gallons by 2030 |
| Japan target | 10% by 2030 |
| Korea target | 1% by 2027, 5% by 2030 |
| India target | 1% by 2027 |
Major SAF producers
- Neste (Finland/Netherlands, HEFA leader).
- World Energy (US, largest US HEFA).
- LanzaJet (US, ATJ commercial deployment).
- Fulcrum BioEnergy (US, MSW pathway, insolvent 2024).
- Gevo (US, isobutanol to SAF).
- Aemetis (US, feedstock and ATJ).
- Twelve (US, PtL emerging).
- Infinium (US, PtL emerging).
Airline demand
Major airlines have signed multi billion dollar offtake agreements: Delta, United, American Airlines, Alaska, Southwest, IAG, Lufthansa, JetBlue, and others. Corporate customers driving demand through business travel commitments.
Feedstock limitations
Cost economics
| Fuel | Price USD per gallon |
|---|---|
| Conventional jet fuel | USD 2 to 3 |
| HEFA SAF | USD 4 to 8 |
| ATJ SAF | USD 5 to 10 |
| PtL SAF (early) | USD 8 to 15 |
| Target PtL SAF 2035 | USD 5 to 7 |
US federal support
IRA provides SAF Blender Tax Credit up to USD 1.75 per gallon for high emissions reduction fuels. Additional support through USDA and DOE programmes. State programmes in California, Illinois, Washington, Minnesota provide additional incentives.
EU support
EU ReFuelEU mandates rising SAF blending. EU Innovation Fund grants for production. Corporate procurement supports demand. Alliance for Sustainable Aviation Fuel Deployment coordinates.
Power to Liquid: the future
Power to Liquid uses renewable powered green hydrogen combined with captured CO2 to synthesise jet fuel. Effectively unlimited feedstock potential. Multiple pilot plants operating. First commercial scale plants late 2020s. Higher cost but scalable.
Aviation alternatives
- Hydrogen aircraft: hypothetical, needs new infrastructure and design.
- Electric aircraft: only viable for very short haul currently.
- Hybrid electric: emerging for regional aviation.
- Efficiency improvements: continued incremental gains.
- Operational optimisation: air traffic management, aircraft utilisation.
- Demand reduction: contested political option.
Global aviation emissions
Aviation emissions were about 900 million tonnes CO2 pre pandemic. Projected to grow to 1.5 billion by 2050 without decarbonisation. SAF is the primary tool for this trajectory. IATA aviation industry commits to net zero 2050 with SAF as key lever.
Corporate procurement
Business travel is driving SAF demand. Google, Microsoft, Amazon, and other corporations paying premium to displace their flight emissions. Sustainable Aviation Buyers Alliance coordinates.
Contemporary challenges
- Feedstock supply constraints.
- High production cost.
- Investment financing.
- Certification of new pathways.
- Airport infrastructure adaptation.
- Global supply chain establishment.
- Balancing sustainability criteria.
Where SAF is going
- HEFA production scale up 2025 to 2027.
- ATJ and cellulosic pathways scaling late 2020s.
- PtL first commercial plants late 2020s.
- EU mandates driving demand growth.
- Cost reduction as scale increases.
- Feedstock diversification.
- Global airline commitments strengthening.
Frequently asked questions
What is SAF?
Sustainable aviation fuel. Drop in replacement for jet fuel from renewable feedstocks.
How is SAF made?
HEFA from waste oils; ATJ from alcohol; PtL from renewable power plus CO2.
Does SAF cost more?
Yes 2 to 5x conventional jet fuel currently.
Does SAF reduce emissions?
Yes 50 to 90 percent lifecycle reduction.
Can I fly on SAF today?
Yes but SAF is only about 0.2 percent of jet fuel today.
Will SAF solve aviation emissions?
Primary near term tool. Long term needs additional technologies.
Who produces SAF?
Neste dominates. Growing US producer base.
What is Power to Liquid?
Synthetic jet fuel from renewable hydrogen and CO2.
Is airline SAF real?
Yes major airlines have SAF offtake contracts.
Where can I read more?
IATA, ATAG, SkyNRG, national aviation departments.
Summary
Sustainable aviation fuel is the primary near term decarbonisation tool for aviation. HEFA dominates current production; ATJ and Power to Liquid pathways emerging. EU and US mandates driving demand. Cost premium 2 to 5x conventional currently. Federal and state incentives support production. Feedstock constraints limit HEFA long term; PtL enables scale. Aviation industry committed to SAF as core net zero 2050 strategy.
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