Europe has finally decided that using sustainable aviation fuel (SAF) is no longer a niche experiment and should become a legal requirement. Under the new ReFuelEU Aviation regulation, this initiative is part of the EU’s “Fit for 55” package, aiming to significantly reduce the aviation sector’s greenhouse gas emissions to meet climate targets.

In this, fuel suppliers at EU airports will be required to blend a minimum share of SAF into all jet fuel sold at the airports: 2% in 2025, 6% until 2030 and then steep increases up to 70% by 2050.

With this regulation, the EU effectively rewrites the rules of fuel use in aviation, pushing airlines, fuel suppliers and investors to redesign how flights to and from Europe are planned and financed.

What ReFuelEU Does Pragmatically?

ReFuelEU addresses itself on the supply side. Any provider of jet fuel at an EU airport must comply with a minimum percentage of SAF on their deliveries. Airlines have no alternative, if they’re refueling in the EU, they’re buying a blend that includes some SAF by default.

SAF utilization is still in its very early stages. – around 1 million tonnes in 2024 versus over 300 million tonnes of jet fuel demand. Hitting 2% and then 6% in Europe alone means the SAF production needs to ramp up very quickly, with Europe becoming a core guaranteed market for producers.

The Cost Gap: Why Is This Important to Airlines?

SAF is much more expensive than fossil jet fuel. Industry estimates usually set the price of SAF to that of fossil based jet fuel at 2-5x more. Even small blends increase the average cost of fuel per tonne. At 2% SAF blend the cost impact is still modest, but once the share rises to 6% and beyond it starts to reshape the fuel cost structure. IATA already estimates that, at current low volumes, SAF adds billions of dollars to the annual fuel bill of airlines. As mandates scale, that premium cannot be ignored in pricing, fleet planning and route decisions.

How Airlines Are Adapting to ReFuelEU?

1. Pricing and Revenue Strategy

Airlines are already attempting to distribute the increased cost of fuel throughout the revenue base by:

• Slightly increased average fares on routes encountering EU airports.
• Specially devoted “sustainability” or fueling surcharges.
• Business travel deals where companies pay extra to support SAF use.

Because they cannot simply raise fares too much, airlines will try to fly with fuller planes, earn more from extras like baggage and seat fees, and charge higher prices mainly to passengers who can afford to pay more (such as last-minute business travellers).

• Fleet Renewal and Efficiency

Because every tonne of fuel is ever more expensive once SAF is blended in it, burning less fuel per seat is more valuable than ever before.

New-generation aircraft (A320neo, 737 MAX, A350, 787, etc.) typically cut fuel burn per seat by 15–25% compared with older models. Under ReFuelEU, that works out to lower SAF and carbon cost per passenger. Even though the policy doesn’t mention aircraft types, but it tilts the economics strongly toward newer fleets and away from ageing  jets.

• Fuel Procurement and SAF Deals

Even though the law formally targets fuel suppliers, airlines still feel the impact because they depend on how much SAF is available and at what price. Big airlines are already signing long-term contracts to reserve SAF in advance, and some are even investing in SAF production plants with energy companies. At the same time, fuel suppliers, airlines and ultimately, passengers are all negotiating how to share the extra cost of SAF.

This means that large airline groups that secure early, reliable SAF supply may end up with a cost and availability advantage, while smaller carriers could face higher prices or tighter supply.

• Network and Hub Choices

Any airline that fuels at an EU airport must use the SAF blend, but the route they choose still makes a difference:

• Some long-haul traffic can be diverted through hubs outside the EU and escape the EU climate rules to a certain extent but not completely.
• EU airlines that adopt SAF and efficient fleets early can present themselves as the ‘greener’ choice for business travelers.
• Very price-sensitive intra-EU routes could see pressure on capacity if SAF-driven fuel costs cannot be covered.

Risks and Opportunities

For airlines, ReFuelEU is both a risk and a forced innovation driver. For fuel producers and investors, it provides a regulated demand floor that can make SAF projects, which would otherwise be too risky to proceed.
For policymakers, ReFuelEU also shows both the benefits and trade-offs of strict climate rules:

• On the positive side, it pushes aviation towards genuine emission cuts, because airlines are using cleaner fuel instead of only buying carbon offsets.
• On the downside, if SAF remains expensive or hard to get, Europe could see higher average airfares and fewer flights on remote routes. To avoid this, the SAF mandate needs to be matched with support for new SAF plants, clear rules on what counts as sustainable, and regular checks on how the policy is affecting prices and connectivity.

Conclusion

ReFuelEU Aviation is a concrete rule that changes how aviation in Europe actually operates. By mandating a growing proportion of SAF to be sold at European airports, it changes the cost structure of flying to, from and in Europe. And the airlines now have to treat the fuel strategy, fleet efficiency and access to SAF as the central pillars of their business models and not side issues. How quickly they adapt and how well policymakers support SAF supply and manage side effects will help decide which carriers and hubs are strongest in the next phase of global aviation.