Sustainable Aviation Fuel Guide: Types, Availability, and Real-World Cost

What Is Sustainable Aviation Fuel?

Sustainable Aviation Fuel (SAF) is a class of aviation fuels produced from non-petroleum feedstocks that can reduce lifecycle greenhouse gas emissions compared to conventional fossil-derived jet fuel. The defining characteristic of SAF is that it qualifies as a "drop-in" fuel — it is chemically compatible with existing aircraft engines, fuel systems, and ground infrastructure, requiring no modification to aircraft or airports. This compatibility is ensured by blending SAF with conventional jet fuel at approved ratios (currently up to 50% for most SAF types, with some pathways approved up to 100%) and by ASTM D7566, the industry standard specification that SAF must meet before it can be used in commercial aviation.

The "sustainable" in SAF refers to the lifecycle greenhouse gas reduction compared to conventional fossil jet fuel. The key metric is lifecycle CO₂ emissions per unit of energy, measured from feedstock cultivation or collection through fuel production and combustion — the well-to-wake emission factor. CORSIA's SAF sustainability criteria require a minimum 10% lifecycle GHG reduction versus fossil jet fuel; most approved SAF pathways achieve reductions of 50–90%, with some reaching near 100% under optimal conditions. The wide range reflects the diversity of feedstocks and production processes: waste cooking oil converted to jet fuel achieves approximately 80% reduction; agricultural residue gasification achieves 70–95%; power-to-liquid (electrofuel) pathways using renewable electricity can achieve near-100% lifecycle reduction in CO₂ emissions.

SAF does not eliminate all aviation climate impacts. Even a 100% lifecycle reduction in CO₂ does not address non-CO₂ forcing effects — contrail formation, NOₓ emissions, and water vapor impacts occur when SAF burns, just as with fossil jet fuel. Some research suggests that SAF's combustion chemistry (particularly lower aromatic content) may reduce the particle precursors that seed contrail ice formation, potentially reducing contrail warming effects. A 2023 study in Nature from researchers at Imperial College London and the German Aerospace Center (DLR) found that alternative fuels with reduced aromatics formed contrails with lower particle number concentrations that warmed the atmosphere less — but this benefit depends on flight conditions and atmospheric state, and is not universally achievable.

The economic and regulatory distinction between SAF and conventional jet fuel (Jet A-1 or Jet A) is important. Jet A-1 is produced from petroleum through a long-established, highly optimized refining process at commodity costs. SAF is produced through newer, more expensive processes from varied feedstocks, with production costs that depend heavily on feedstock availability, plant scale, and technology maturity. The cost premium of SAF over fossil jet fuel is the central barrier to its large-scale adoption, and most of the policy and investment discussion in the industry revolves around how to close this cost gap.

SAF Production Pathways: From Feedstock to Fuel

ASTM D7566 currently approves eight distinct SAF production pathways, each using different feedstocks and conversion technologies. These pathways have different emission reduction profiles, feedstock limitations, and maturity levels, and understanding them is essential to assessing SAF's scalability and climate potential.

Hydroprocessed Esters and Fatty Acids (HEFA) is the most commercially mature and currently dominant SAF pathway. HEFA converts fats, oils, and greases — including used cooking oil (UCO), tallow, soybean oil, camelina oil, and other lipid feedstocks — into jet fuel through hydroprocessing (adding hydrogen at high temperature and pressure to convert lipid molecules to hydrocarbons). HEFA SAF achieves lifecycle GHG reductions of 50–80% depending on feedstock, and it can be blended up to 50% with conventional jet fuel. The main constraint is feedstock availability: UCO production in the EU is approximately 2.6 million tonnes per year, which would produce roughly 1.3 billion liters of HEFA SAF — significant, but still a fraction of the 75 billion liters of jet fuel the EU consumes annually. Scaling HEFA significantly beyond UCO requires food-competing crops (soybean, palm) or would require dedicated energy crops — both problematic from a sustainability perspective.

Fischer-Tropsch Synthesis (FT-SPK) converts any carbon-containing feedstock — biomass, municipal solid waste, coal, or CO₂ — via syngas (a mixture of CO and H₂) into hydrocarbons using the Fischer-Tropsch process. FT-SAF can be blended up to 50% and achieves lifecycle reductions of 40–95% depending on feedstock and process. Biomass-to-liquid FT facilities have been demonstrated at commercial scale (Velocys in the UK, Red Rock Biofuels in the US), but capital costs are high and the process requires large, centralized facilities. Municipal solid waste (MSW)-to-jet fuel via FT gasification is an attractive pathway because it uses non-competing waste feedstocks and simultaneously addresses waste disposal — Fulcrum BioEnergy's Sierra BioFuels plant in Nevada became the first commercial-scale MSW-to-SAF facility to reach production in 2022, though at modest volumes.

Alcohol-to-Jet (ATJ) converts alcohols — ethanol or isobutanol — derived from fermentation of cellulosic biomass or agricultural residues into jet fuel via dehydration and oligomerization. LanzaTech's ethanol fermentation from industrial waste gases (captured from steel mills) combined with an ATJ conversion step is a notable commercial pathway: the steel mill's waste CO is captured, fermented to ethanol by proprietary microorganisms, and converted to jet fuel, achieving lifecycle GHG reductions that can exceed 90%. Virgin Atlantic's SAF100 transatlantic flight in November 2023, which used 100% SAF on one engine (with the other running conventional fuel), used LanzaJet ATJ fuel from this pathway.

Power-to-Liquid (PtL), also called electrofuel or e-fuel, produces jet fuel from CO₂ captured from the atmosphere (or industrial sources) and hydrogen produced by electrolysis of water using renewable electricity. The overall process — capture CO₂, produce green hydrogen via electrolysis, synthesize Fischer-Tropsch jet fuel — results in near-zero net CO₂ emissions because the atmospheric CO₂ used in production is re-emitted at combustion, creating a closed carbon cycle. PtL is the only SAF pathway that is not feedstock-limited in principle — it uses atmospheric CO₂ and renewable electricity, both available in essentially unlimited quantities. The barrier is cost: producing green hydrogen is expensive (currently $4–8 per kg; fossil hydrogen costs $1–2 per kg), and the overall PtL fuel production cost is approximately $4–8 per liter, versus $0.50–0.80 per liter for fossil jet fuel. PtL is currently 5–10 years away from commercial-scale production at any significant volume.

Current SAF Supply: Scale and Key Producers

Global SAF production in 2023 reached approximately 600 million liters, representing roughly 0.2% of global aviation fuel demand of approximately 300 billion liters. This is a significant increase from the 50 million liters produced in 2021, driven by regulatory mandates in the EU, corporate sustainability commitments from airlines, and policy support in the US through the Inflation Reduction Act's SAF blender's tax credit. However, the production trajectory must increase by orders of magnitude — to approximately 30 billion liters by 2030 to meet IATA's aspirational targets — a scaling requirement that most analysts consider highly challenging.

The United States has become the world's largest SAF producer, driven by the Inflation Reduction Act (IRA) provisions that provide a blender's tax credit of $1.25–1.75 per gallon for SAF meeting minimum lifecycle reduction thresholds, plus additional credits for higher-reduction pathways. Major conventional fuel producers including World Energy, SkyNRG USA, and Neste (through its US operations) have expanded SAF production capacity significantly since the IRA's passage in August 2022. Neste, the Finnish refiner that has become the world's largest SAF producer, operates a HEFA SAF facility in Porvoo, Finland and has expanded its Singapore and Rotterdam refineries for SAF production, with total SAF capacity approaching 1.5 million tonnes per year (approximately 1.8 billion liters).

The European Union's RefuelEU Aviation regulation, which entered into force in January 2025, mandates minimum SAF blending percentages for aviation fuel suppliers at EU airports: 2% from 2025, scaling to 6% by 2030, 20% by 2035, 34% by 2040, and 70% by 2050. Critically, sub-mandates within the overall target require minimum shares of synthetic SAF (PtL) — 1.2% from 2030, 35% from 2045 — to drive investment in PtL as the pathway with greatest long-term scalability. Airlines and airports are required to blend the mandate percentages; fuel suppliers must make compliant fuel available. Penalties for non-compliance can reach the equivalent of 10 times the difference between the market price of conventional fuel and SAF for the non-compliant volume.

Asia-Pacific SAF supply is developing more slowly than European and North American production, despite the region's large and rapidly growing aviation market. Singapore Airlines, Cathay Pacific, and Japan Airlines have all made significant SAF purchase commitments, but production infrastructure in the region is limited. Singapore has established an SAF levy that applies to all international departing flights from Changi Airport starting in 2026, with revenues directed to SAF procurement. Japan's Ministry of Land, Infrastructure, Transport and Tourism (MLIT) has set a target of 10% SAF in domestic aviation fuel by 2030. These policies signal demand, but supply development will require more aggressive investment in production facilities.

The SAF Cost Premium: Barriers and Pathways to Parity

SAF currently costs approximately 3–8 times more than conventional fossil jet fuel, depending on feedstock, production pathway, and market conditions. At conventional jet fuel prices of $0.70–0.90 per liter, HEFA SAF from UCO costs approximately $1.50–2.50 per liter; FT-SAF from biomass costs $2.00–3.50 per liter; PtL SAF costs $4.00–8.00 per liter. The cost premium has a direct impact on airline operating economics: aviation fuel represents 20–30% of airline operating costs, and increasing fuel cost by even 50% would eliminate profitability for most carriers at current ticket pricing.

The IRA blender's tax credit in the United States substantially reduces the effective cost premium for airlines purchasing domestic SAF. The $1.25/gallon base credit (approximately $0.33/liter) narrows the gap between UCO HEFA SAF and conventional fuel significantly, and the additional lifecycle performance bonus can bring the credit to $1.75/gallon ($0.46/liter). Combined with Inflation Reduction Act investment tax credits for new SAF production facilities, the US policy support is substantial. EU RefuelEU's mandates will create a compliance demand that allows SAF producers to charge a premium, effectively passing the cost to airlines and eventually to passengers.

The path to cost reduction follows the learning curve logic common to new energy technologies. As SAF production scales, capital costs per unit capacity decline (economies of scale), feedstock procurement becomes more efficient, and process optimization reduces operating costs. BloombergNEF and Rocky Mountain Institute cost modeling suggests that HEFA SAF could reach cost parity with conventional jet fuel by the mid-to-late 2030s if production scales to approximately 10% of global fuel demand, driven by policy mandates and economies of scale. PtL SAF cost parity requires the cost of renewable electricity and electrolytic hydrogen to continue declining — achievable by 2040 if current renewable energy cost trends continue — combined with substantial scale-up in production capacity. The IEA's Net Zero Emissions by 2050 scenario requires SAF to constitute 45% of aviation fuel by 2050, a level that would require an extraordinarily rapid scale-up from current levels.

The consumer cost impact of SAF mandates is more modest than airline fuel economics might suggest. Airlines do not pass fuel costs directly to specific routes; fuel surcharges are applied broadly across the network. IATA's analysis of the EU RefuelEU 2% SAF mandate from 2025 estimated an average ticket price increase of approximately €1.50–3.00 per short-haul flight and €4.00–8.00 per long-haul flight. At higher mandate levels in 2030 (6%), estimated ticket price impacts are €5–10 per flight for short-haul and €15–30 for long-haul. These are significant but not prohibitive amounts, and they are comparable to other environmental levies already applied to aviation in several European countries.

Government Mandates and Policy Landscape

Government policy is the primary driver of SAF scale-up investment, because without mandates or sufficiently high carbon prices, airlines have limited financial incentive to purchase more expensive SAF over conventional fuel. The policy landscape is evolving rapidly, with the EU's RefuelEU regulation setting the most comprehensive mandatory framework currently in force.

The United Kingdom published its Jet Zero Strategy in 2022, including a SAF mandate of 10% by 2030 and 22% by 2040. The UK government worked with industry on a revenue stabilization mechanism to reduce SAF price volatility risk for producers, addressing one of the investment barriers that has slowed production facility construction. The UK mandate applies to all flights departing from UK airports, creating a demand base for UK SAF production.

The United States does not have a federal SAF volume mandate (as of early 2026), relying primarily on the IRA tax credit as a demand incentive. The Biden administration set a goal of 3 billion gallons (approximately 11 billion liters) of SAF production by 2030 — roughly 10% of US aviation fuel demand — and invested in research and supply chain development through the SAF Grand Challenge, a multi-agency initiative coordinated by the Department of Energy. Whether these targets are achievable without a volume mandate is debated; without a legal requirement to purchase SAF, airlines may prefer to use the tax credit to reduce costs rather than scale up purchases significantly above market equilibrium.

Japan's Basic Plan for Aviation includes SAF targets aligned with its broader carbon neutrality commitments, and the Japan-specific SAF production ecosystem is developing with investment from ENEOS (Japan's largest oil refiner) and IHI Corporation. Singapore, Norway, and Sweden have domestic SAF mandates or levies designed to develop domestic supply chains. The proliferation of national and regional policies creates a fragmented regulatory environment for airlines operating globally, with different compliance requirements at different airports — a complexity that IATA is working to harmonize through engagement with ICAO to develop global SAF accounting standards compatible with CORSIA.

The SAF supply-demand trajectory for the next decade will be substantially shaped by the interaction between EU RefuelEU mandates (creating guaranteed demand), IRA tax credits (subsidizing US production), and the investment decisions of major fuel producers who are evaluating multi-billion dollar SAF production facilities. The window in which these investment decisions must be made — 2024–2028 — is now open, and the policy signals being sent in this period will determine whether SAF achieves the 5–10% market share by 2030 that most scenarios require as a stepping stone to the 40–70% shares needed by 2050.