Aviation moves about 4% of global CO₂ emissions. Unlike road transport, it can't electrify · batteries are too heavy, hydrogen infrastructure doesn't exist at scale, and nothing beats the energy density of liquid hydrocarbons for anything flying more than 1,000 km. The industry has exactly one viable decarbonisation lever for the next 15–20 years: replace fossil kerosene with sustainable aviation fuel.
SAF is not a new molecule. It's jet fuel · chemically identical to the Jet A-1 running through today's aircraft · produced from non-petroleum feedstocks. That last part is what does the work. Where the carbon in the fuel came from before it became fuel determines the lifecycle emissions. SAF pathways reduce CO₂ by 50–99% compared to fossil jet, depending on feedstock and production route.
The drop-in principle
The single most important thing to understand about SAF is this: you can pour it into any existing jet engine, today, with zero modifications. No new fuel trucks. No new pipelines. No airport retrofits. No aircraft certification work beyond what's already been done.
That's the drop-in principle. ASTM D7566 · the fuel specification · allows SAF to be blended with conventional jet up to 50% (the cap is regulatory, not technical; several pathways have been flown at 100%). Physically the molecules behave the same as fossil jet because they are the same molecules, just synthesised from different starting materials.
This is why aviation is taking SAF seriously while it continues to argue about hydrogen. Every kilo of SAF that enters the system today reduces emissions from day one, using infrastructure that already exists.
The five pathways you need to know
SAF can be produced through a handful of industrial processes, each using different feedstock. The commercially relevant routes in 2026:
| Pathway | Feedstock | TRL | Typical cost (USD/t) |
|---|---|---|---|
| HEFA | Used cooking oil, tallow, palm residues | 9 (commercial) | 1,500–2,000 |
| ATJ | Ethanol, isobutanol, other alcohols | 8 (early commercial) | 2,000–2,800 |
| FT | Biomass or MSW syngas | 7–8 (demonstration) | 2,200–3,200 |
| PtL (e-SAF) | Green H₂ + captured CO₂ | 6–7 (pre-commercial) | 3,000–5,500 |
| PBtL | Plasma-gasified biomass + H₂ | 5–6 (pilot) | Not yet commercial |
HEFA (Hydroprocessed Esters and Fatty Acids) is the workhorse of today's market · almost every operating commercial SAF plant runs HEFA. Fats and oils are hydrogenated into straight-chain alkanes, then isomerised into jet fuel. Cheap, proven, but feedstock-constrained: the world doesn't have enough waste oil to meet aviation demand.
ATJ (Alcohol-to-Jet) converts ethanol or isobutanol into jet fuel via dehydration, oligomerisation, and hydrogenation. Its advantage is feedstock flexibility · any ethanol source will do. LanzaJet's first commercial ATJ plant came online in Georgia in 2024.
FT (Fischer-Tropsch) is a hundred-year-old gas-to-liquids process. Biomass or municipal solid waste is gasified to syngas, then synthesised into liquid hydrocarbons. Expensive, but it can handle messy feedstock that nothing else can touch.
PtL (Power-to-Liquid), also called e-SAF, is the structural long-term answer. Green hydrogen (from renewable electricity) reacts with captured CO₂ to produce synthetic kerosene. No biogenic feedstock required, so it scales with electricity capacity · which scales infinitely. Expensive today; the cost curve depends on electrolyser CAPEX and green electricity prices.
PBtL (Plasma-Biomass-to-Liquid) is the newcomer. Plasma gasification handles feedstock other routes struggle with and combines with green hydrogen for better carbon efficiency. Still pilot-stage.
Why the price gap exists
Fossil jet fuel costs roughly 700–900 USD per tonne. SAF costs 1,500–5,500 USD per tonne depending on pathway. That's a 2–6× multiple, concentrated mostly in feedstock cost and, for PtL, green hydrogen cost.
The premium is not a technology problem. It's a feedstock problem for biogenic routes, and an electricity-cost problem for PtL.
No innovation breakthrough closes that gap. What closes it is (a) scale, (b) feedstock-cost reductions as markets mature, and (c) regulation that makes the fossil alternative more expensive or the SAF alternative cheaper. All three are happening. None of them happen quickly.
Why airlines are buying anyway
Three reasons, in order of weight:
- Regulation. ReFuelEU Aviation mandates 2% SAF blend at EU airports in 2025, 6% in 2030, 20% in 2035, 70% by 2050. The UK, Japan, India, and Brazil are drafting similar mandates. CORSIA creates a global offsetting floor. Non-compliance is more expensive than compliance.
- Corporate reporting. Scope 3 disclosures, SBTi targets, and customer-facing ESG commitments push airlines toward emissions reduction on a fixed timetable. SAF is the only lever that actually moves those numbers.
- Hedge against future price shocks. Long-term offtake at today's premium locks in supply certainty. When mandates bite and availability tightens, early signers keep their allocations.
The result is a market where 582 production facilities are now tracked globally at various stages, roughly 95% of them still pre-FID (pre-Final Investment Decision). The capital gap to get that pipeline funded through 2030 is around $45B. That's the shape of the opportunity: demand is mandated, supply is scarce, and most of the projects that need to exist don't exist yet.
What a decision-maker actually needs to know
If you're an airline or offtake buyer:
- Secure offtake now, at today's premium, for allocation certainty post-2030.
- Diversify pathway exposure. HEFA is cheapest today but constrained long-term. PtL is expensive today but unconstrained. Book-and-claim (buying the sustainability attribute without physical delivery) lets you separate the two.
- Watch feedstock prices · UCO, tallow, green H₂. They're the leading indicator of SAF cost, 6–12 months ahead.
If you're an investor:
- The 2024–2030 window is HEFA-heavy. The 2030–2040 window is PtL. Portfolio construction should bridge both.
- Offtake contracts are the collateral. No offtake, no financeable project.
- Regulatory exposure is the tailwind, but also the risk: mandate design is evolving, and poorly-structured mandates (price caps, loose sustainability criteria) can collapse margins.
If you're a producer:
- You need visibility to buyers and capital before FID, not after. The capital gap is on early-stage projects.
- Certification matters. ISCC, RSB · buyers require a sustainability certificate that matches their reporting framework.
- Feedstock strategy is the differentiator. Everyone is chasing UCO. Nobody has solved the PtL electricity-sourcing problem.
Bottom line
SAF is the aviation industry's only decarbonisation answer for the next two decades, it's substantially more expensive than fossil jet, and the world is going to buy a lot of it anyway because regulation requires it. The winners on both sides of that trade · producers who get their capacity financed, and buyers who secure allocation early · are making their decisions now.
The market the industry is missing isn't supply of fuel. It's a place where real producers, real buyers, and real capital can find each other with verified data. That's the gap e-fuels·com was built to close.