How Sustainable Aviation Fuel (SAF) Is Transforming Aviation

The fueler hands you the delivery note in Amsterdam and there it is, halfway down the page: a sustainable aviation fuel blend share, certified and logged. The aircraft does not notice. The engines do not notice. The paperwork notices a great deal — and behind that quiet line on the fuel docket sits the biggest change in what we burn since the jet age began.

When this article first ran, the EU’s 2 percent blend mandate had just taken effect. Eighteen months later the picture is sharper, and not all of it is good news: production has doubled but its growth rate is already slowing, the next mandate steps are dated and priced, and the gap between what regulators demand and what refineries deliver has become the central story. Every figure below was re-verified in June 2026, with sources listed at the end.

Where SAF Production Actually Stands

Start with the honest numbers. IATA’s outlook of 9 December 2025 puts global SAF production at 1.9 million tonnes for 2025 — double the 1 million tonnes of 2024, but a downward revision from earlier forecasts and only 0.6 percent of all jet fuel burned worldwide. For 2026, IATA forecasts 2.4 million tonnes, about 0.8 percent of global jet fuel use.

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Source: IATA SAF outlook, 9 December 2025.

The headline behind the headline: growth is slowing. IATA flagged in December 2025 that production keeps falling short of industry expectations, mainly because weak policy support and a stubborn price premium leave existing capacity under-used. The fuel works; the economics still limp.

The Mandates: ReFuelEU, the UK Rule, and CORSIA

ReFuelEU Aviation: the EU blend ladder

Since 1 January 2025, ReFuelEU Aviation requires fuel suppliers at EU airports handling more than 800,000 passengers (or 100,000 tonnes of freight) a year to blend at least 2 percent SAF. The ladder is written into law, and the steps are steep.

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Source: European Commission, ReFuelEU Aviation regulation, checked June 2026.

One flexibility worth knowing: until the end of 2034, suppliers may average their SAF obligation across all the EU airports they serve instead of hitting the percentage at every single hydrant. That is why the actual blend share varies from airport to airport even inside the EU.

The UK mandate: close to target, watched closely

The UK runs its own scheme, also live since January 2025: 2 percent in year one, rising on a straight line to 10 percent in 2030 and 22 percent in 2040. Department for Transport data reported by GreenAir News shows SAF reached 1.63 percent of UK jet fuel between January and late October 2025 — close to target, though final compliance figures are only due in late 2026. A revenue certainty mechanism to underwrite new UK SAF plants is expected to be in place by the end of 2026, and the UK’s synthetic e-SAF obligation starts earlier than the EU’s, in 2028.

CORSIA: the voluntary years end in 2026

CORSIA, ICAO’s global carbon offsetting scheme, is flying the final year of its voluntary first phase (2024–2026), with 130 states participating as of 2026 — Vietnam joined on 1 January 2026. From 1 January 2027, the second phase makes participation effectively mandatory for most international aviation. SAF is one of the main ways airlines can shrink their offsetting bill, which keeps long-term demand pointed firmly up (IATA CORSIA fact sheet, June 2026).

How SAF Is Made: Four Pathways, One Specification

All certified SAF ends up in the same place: blended with conventional fuel and released as standard Jet A-1. How it gets there differs.

• HEFA (hydroprocessed esters and fatty acids) — refined from used cooking oil and waste fats. The workhorse: the overwhelming majority of SAF flying today is HEFA-based.
• Alcohol-to-Jet — converts ethanol and other alcohols made from agricultural residues into jet fuel.
• Fischer-Tropsch — gasifies municipal waste and forestry residues into synthetic crude, then refines it into jet fuel.
• Power-to-Liquid (e-SAF) — synthesizes fuel from captured CO2 and green hydrogen. The long-term prize, and by far the priciest: IATA warned in December 2025 that e-SAF can cost up to 12 times conventional jet fuel today.

Across pathways, IATA uses up to 80 percent lifecycle CO2 reduction as the working figure for SAF versus fossil jet fuel; the exact number depends on feedstock and process. E-SAF made with renewable power and captured carbon approaches full lifecycle neutrality on paper — which is exactly why regulators wrote it a dedicated quota.

What Airline Crew Actually Notice on the Line

Flight deck: a drop-in fuel, by design

SAF is certified under ASTM D7566 and, once blended — currently up to a maximum of 50 percent — the batch is re-identified as ordinary ASTM D1655 Jet A-1. That one sentence does all the operational work: same fuel specification, same performance numbers, same FCOM, same MEL. There is no SAF checklist, no SAF NOTAM, and no special entry in your flight plan. If a blend did not meet the specification, it would simply never be released as Jet A-1.

Where you will see it is paper. Fuel delivery notes and station documentation increasingly show the blend share, because every mandated litre has to be tracked through a certified chain of custody. Expect more of that, not less, as the EU ladder climbs.

Tankering into the EU just got harder

Here is the piece of ReFuelEU most crews have not read: the anti-tankering clause. Aircraft operators must uplift at least 90 percent of their yearly fuel requirement at each EU airport, a rule written specifically to stop carriers hauling cheaper, unblended fuel into mandate territory. If your airline’s fuel policy on EU rotations has shifted recently, this rule is one reason why (European Commission, ReFuelEU Aviation, checked June 2026).

The road to 100 percent SAF

Virgin Atlantic flew the first 100 percent SAF transatlantic crossing by a commercial airline in November 2023, using an 88 percent HEFA and 12 percent synthetic aromatic kerosene blend on a Boeing 787. Rolls-Royce confirmed in 2023 that all its in-production civil engines are compatible with 100 percent SAF, and Boeing and Airbus have both committed to delivering aircraft ready for 100 percent SAF around 2030. The remaining hurdle is the specification itself: the 50 percent cap exists largely because conventional fuel supplies the aromatics that keep certain fuel-system seals tight, and ASTM certification work on fully synthetic blends continues.

The Money Problem

SAF remains roughly twice the price of conventional jet fuel on average — and up to five times more expensive in mandated markets, where compliance costs stack on top, according to IATA’s December 2025 assessment. IATA also warned that with e-SAF obligations approaching (UK in 2028, EU in 2030), European compliance costs could escalate to 29 billion euros by 2032 if production does not scale fast enough.

Airlines keep signing anyway, because the mandates leave no choice and the net-zero math does not work without it: IATA’s roadmap attributes around 65 percent of the emissions cuts aviation needs by 2050 to SAF. Air France-KLM is contracted toward a 10 percent SAF share by 2030, including multi-year deals for 1.6 million tonnes from Neste and DG Fuels. United Airlines reported growing its SAF supply to six of its hubs during 2025. Commitments like these are what eventually pull new refineries out of the ground.

SAF will keep showing up in your briefings, your fuel paperwork, and your company comms for the rest of your career — that much is now locked in by law. For the human side of a sustainable operation, our pilot fatigue safety guide covers the part of the equation nobody mandates: sustainable rosters.

Sustainable Aviation Fuel: Crew FAQ

Sources: IATA SAF production outlook, 9 December 2025; IATA CORSIA fact sheet, June 2026; European Commission, ReFuelEU Aviation; UK Department for Transport SAF mandate data (January–October 2025) as reported by GreenAir News; ICAO CORSIA state listings 2026; Air France-KLM newsroom; United Airlines 2025 results filing. All figures checked 12 June 2026.

Disclosure: this article contains no sponsored links. AirlineCrewDiscount.net earns affiliate commission on selected partner links elsewhere on the site, at no extra cost to you. Mandates, forecasts, and programme details change; always confirm current rules with your operator and the primary sources above.