Green Flying Costs You Twice: What Sustainable Aviation Fuel Actually Costs in 2026

There is a line item on European airfares that most travellers have never noticed, and it is the closest thing aviation has to a green tax. Sustainable aviation fuel — SAF, jet fuel refined from waste oils and, eventually, synthesised from green hydrogen and captured carbon — is mandated by EU law, it costs roughly twice what ordinary jet fuel costs, and in 2026 you pay for it in two separate places.

The interesting part is not that SAF is expensive. It is why the maths looks the way it does: the price gap between SAF and jet fuel actually narrowed in 2026, and almost nobody noticed, because the thing that narrowed it was an oil shock.

The headline number: SAF costs about 2x to 2.5x jet fuel

Three dated, independent sources land in the same band:

• IATA, June 2026: SAF at USD 2,872/tonne (USD 374/barrel) against a 2026 jet fuel forecast of USD 152/barrel — a 2.5x multiple. IATA’s own time series shows the multiple moving 2.4x (2024) to 3.1x (2025) to 2.5x (2026).
• BloombergNEF, 16 July 2026: Northwest Europe Q2 2026 averaged USD 2,830/tonne for SAF (USD 8.58/gallon) against USD 1,404/tonne for jet fuel — ~2.0x, the cleanest like-for-like regional comparison available.
• IATA, December 2025: “SAF prices exceed fossil-based jet fuel by a factor of two, and by up to a factor of five in mandated markets.” Synthetic e-SAF, which the EU will require from 2030, is quoted at up to 12x.

At the extreme end, the EU’s own compliance price — what a supplier effectively pays to satisfy the mandate rather than to trade the fuel — was modelled by IATA at USD 560/barrel in March 2026, against traded SAF at USD 360 and jet at USD 220. IATA’s blunt summary: airlines pay “double the market price of SAF” in mandated markets.

So where does the premium land? IATA puts the SAF premium at USD 3.6 billion added to industry fuel costs in 2025 and USD 4.3 billion in 2026. For 2025 that works out to a USD 2.9 billion premium on 1.9 million tonnes, of which USD 1.4 billion was the ordinary price gap and the rest was compliance fees.

The 2026 twist: the gap closed for the wrong reason

Here is the part that inverts the obvious story.

SAF did not get cheaper in 2026. Jet fuel got more expensive. The Strait of Hormuz closed on 28 February 2026, and IATA’s June forecast has jet fuel averaging USD 152/barrel for 2026 against USD 90 in 2025 — a 69% jump. BloombergNEF recorded SAF in Northwest Europe rising 31% since the war began, to that USD 2,830/tonne average.

Put those together and the multiple compresses: SAF’s absolute price went up while its ratio to jet fuel fell from 3.1x to 2.5x. A casual reading of “the SAF premium is narrowing” concludes the transition is maturing. It is not. The denominator doubled. If the Hormuz disruption reverses, the gap reopens to three times or more, and every fare built on the current ratio under-budgets.

The rule that creates the cost: ReFuelEU, verbatim

The EU mandate is Regulation (EU) 2023/2405, and its Annex I schedule is worth reading exactly as written, because the intermediate years are what people get wrong. The regulation sets checkpoint values, not a smooth curve:

Effective from	Minimum SAF share	Of which synthetic (e-SAF)
1 January 2025	2%	—
1 January 2030	6%	1.2% (averaged 2030-31, 0.7%/yr minimum)
1 January 2035	20%	5%
1 January 2040	34%	10%
1 January 2045	42%	15%
1 January 2050	70%	35%

Two things follow from the text itself. First, the obligation sits on aviation fuel suppliers, not on you or the airline directly — suppliers who miss the minimum share face fines plus an obligation to supply the shortfall in the next reporting period. The cost is recovered commercially down the chain, which is why it surfaces as a fare component. Second, the synthetic sub-mandate is the expensive part: the regulation’s own recitals note e-SAF production costs are “currently estimated at three to six times higher than the market price of conventional aviation fuel.”

Who is affected: the regulation covers airports handling the large majority of EU traffic (its stated scope is at least 95% of departures from EU airports), and it applies to commercial air transport — not military, humanitarian, or state flights. No amendment to the 2023/2405 percentages had been enacted as of October 2026.

The UK legislated separately: the Sustainable Aviation Fuel Act 2026, whose explanatory notes record that SAF achieves lifecycle emissions savings of over 70% versus kerosene, and — the sentence that explains the whole price problem — that commercial plants typically cost GBP 600 million to GBP 2 billion to build and “tend to run at a loss during their first years.”

You pay for it twice, and the airline’s own terms say so

This is the receipts finding, and it comes straight from KLM’s Terms and Conditions for its SAF Option:

“The SAF Option complements the environmental surcharge already included in the fare, where applicable.”

Read that again. The optional SAF contribution you can add at checkout sits on top of a surcharge that is already inside your ticket price. It is not an alternative to paying — it is a second payment.

The same T&C states the SAF price is “adjusted regularly to follow market developments,” which is the airline telling you the number moves with the BloombergNEF index above, and that KLM’s SAF must cut CO2 by at least 65% over its full lifecycle.

What the mandatory surcharges look like, by airline:

• Lufthansa Group — Environmental Cost Surcharge covering both the ReFuelEU SAF mandate and the EU ETS. The group’s own newsroom: the amount “varies depending on the flight route and fare and is between 1 euro and 72 euros.” Long-haul business runs EUR 18-36, first class up to EUR 72. Caveat: the EUR 1-72 band is the last primary-sourced range (June 2024 announcement); a 2026 increase has been reported second-hand but not confirmed against a Lufthansa release.
• Air France — a “Contribution to Sustainable aviation fuel” line in every ticket since 1 January 2025, quoted at EUR 2-10 economy, EUR 3-30 business.
• KLM — environmental surcharge on all Schiphol departures, in the EUR 1-12 range by class and distance.
• United — a genuinely voluntary contribution with fixed tiers of USD 1.00 / USD 3.50 / USD 7.00, not tied to your specific flight’s fuel.
• Delta — no passenger-facing SAF fee found. Delta buys SAF commercially (23 million+ gallons in 2025) and offers no contribution line item. Do not assume one exists.

The structural point: Lufthansa’s and Air France-KLM’s surcharges are mandatory and bundled into the fare — you cannot decline them — while United’s is optional and SAS sells its SAF in 20-minute flight-time blocks. Same fuel, three different commercial models.

What it adds to your ticket: the honest range

The most credible fare-impact estimate comes from Transport & Environment (March 2026), which puts the mandate’s effect on average ticket prices at “limited to 4%” by 2030, with roughly EUR 3 added to a short-haul flight carrying the 1.2% e-SAF blend — “roughly the price of a coffee.”

That is an advocacy organisation arguing the mandate is affordable. The counterweight is IATA, an industry association arguing the opposite, warning that EU e-SAF compliance costs could reach EUR 29 billion by 2032 if the synthetic targets are not met. Both are quoted here with their interest attached; neither is neutral, and the truth sits between a coffee and a crisis.

There is also a real subsidy flowing the other way that almost no traveller knows about: the EU allocated EUR 1.5 billion of ETS allowances to offset airline SAF costs across 2024-2030, worth roughly EUR 100 million to 53 airlines in 2024 alone — covering about 100% of Lufthansa Group’s SAF use and about half of Air France-KLM’s.

The carbon side of the ledger

SAF is not the only green cost on your ticket. The EU Emissions Trading System puts a price on aviation carbon directly, and EU carbon permits closed at EUR 86.85/tonne on 8 October 2026 (cross-checked against ICE December-2026 futures at EUR 85.77 the same day). Flights departing EU airports sit inside that system; long-haul flights beyond the EEA fall under ICAO’s CORSIA offsetting scheme instead, which moves from its voluntary phase to mandatory participation for most states in 2027.

Scale matters when you judge these numbers: global SAF production is expected to reach about 2.4 million tonnes in 2026 — 0.8% of total jet fuel consumption (IATA). The fuel that will cut 70% of aviation’s carbon is, right now, under one percent of what aircraft burn. That is the entire cost problem in one ratio.

What people are actually saying

The reaction to airline SAF fees is split along a predictable line: travellers resent paying a mandatory surcharge for a fuel that is under 1% of supply, while aviation-campaigners argue the surcharge is too small to matter. Two dated, attributable posts capture both ends — verified directly against the platforms’ own APIs, not through search snippets:

• George Monbiot (@georgemonbiot.bsky.social, Bluesky, 16 September 2026): “For years I’ve been told that aviation emissions are negligible, so don’t worry your little head about them. But I’ve kept pointing out that there are - and will be - no good technical solutions, and they’ll keep growing. Now we know just how big the problem is.” (849 likes, 393 reposts)
• ICCT Europe (@iccteu.bsky.social, Bluesky, 3 March 2026): “How can EU Member States reduce the cost gap between sustainable aviation fuels (#SAF) and fossil kerosene? New ICCT research assesses national and EU policy levers to support production of synthetic e-kerosene and cellulosic SAF—fuels needed to meet future EU targets.”
• Aviation Environment Federation (@theaef.bsky.social, Bluesky, 22 April 2026): “Getting sustainable aviation fuel (SAF) right isn’t just about using any alternative fuel — it’s about using the right ones.” (thread header, 1 of 5, pointing at a Greenpeace Unearthed investigation; 2 likes, 1 repost)

The tension across these three is the whole debate in miniature. Monbiot’s position is that no fuel solves aviation’s growth problem — which the 0.8%-of-supply figure above supports. ICCT’s is that the cost gap is a policy problem with policy answers — which the EUR 1.5 billion ETS subsidy and the UK’s revenue-certainty legislation also support. Both can be true, and neither changes what you pay at checkout this year.

The AEF line is the one worth sitting with, because it is the sharpest version of the objection the cost table above cannot express: not all SAF is equivalent, and the 2-2.5x premium buys different things depending on the feedstock. A waste-oil biofuel and an e-kerosene synthesised from green hydrogen both count toward the same EU percentage, and they do not have remotely the same lifecycle savings, land footprint, or price. The EU’s own sub-mandate exists precisely because of that distinction — which is also why the synthetic slice (1.2% from 2030, rising to 35% by 2050) is the expensive part of the schedule.

Sourcing note: Reddit is blocked to our tooling and logged-out search on X and Bluesky returns nothing usable, so these quotes were retrieved by reading specific posts directly through Bluesky’s public AT Protocol, each confirmed for account name and createdAt timestamp. We publish only quotes we could date and attribute this way; everything else we found was undated and is excluded. The buckets we could NOT fill: airline-specific passenger opinion on SAF fees, and any dated discussion of ReFuelEU’s effect on fares.

What this means for you

• Check whether your fare already includes a surcharge. On Lufthansa Group and Air France-KLM tickets it does, and it is not optional. The amount is usually broken out in the ticket’s trip details, labelled something like “Environmental Cost Surcharge.”
• Do not buy an optional SAF contribution and assume you have now paid for green fuel. KLM’s own terms say the option complements a surcharge already in your fare. Ask what the base fare covers first.
• Expect the surcharge to move with oil, in the counterintuitive direction. The 2026 compression of the SAF premium came from jet fuel rising, not SAF falling. A calm oil market reopens the gap.
• The 2030 step is the one to watch. The blend goes 2% to 6% on 1 January 2030, and that is when the synthetic (e-SAF) sub-mandate starts — the component the regulation itself prices at three to six times conventional fuel, and IATA at up to twelve times.
• Voluntary offsets and SAF contributions are not the same thing. A SAF fee buys lower-carbon fuel for a flight; a carbon offset funds a project elsewhere. Airlines sell both, and conflating them is the most common greenwashing move in the industry.

What we could not verify

• The 2026 Lufthansa surcharge amount. A third increase in 2026 has been reported, but only through a secondary source we could not confirm against a Lufthansa or Reuters release. The EUR 1-72 band stands as the last primary-sourced range.
• KLM’s and Air France’s exact current surcharge amounts. Both come from trade press rather than a current airline-published tariff; the T&Cs confirm the charge exists and “is adjusted regularly” but publish no figure. Treat the ranges above as indicative.
• SAS’s per-block SAF price. Sold in 20-minute blocks, but the price is not published on the SAS page.
• IATA’s USD 2,872/tonne versus USD 374/barrel. These two published figures are not exactly consistent under standard conversion; both are quoted as published rather than reconciled.
• Social sentiment beyond three quotes. Reddit is blocked to our tooling, and logged-out search on X and Bluesky returns nothing citable, so community reaction is represented by the three dated posts above — retrieved directly through Bluesky’s public API — rather than a broad sample. Airline-specific passenger opinion on SAF fees and dated discussion of ReFuelEU’s fare impact both came up empty under the dated-and-attributed rule. A fuller social read would need platform access we do not have.

Every figure above carries its source and date. Where sources disagree — the SAF multiple, the fare impact, the surcharge amounts — both are shown with attribution rather than averaged.