Opinion: Europe's Aviation Decarbonisation Gamble: Why Clean Fuel Mandates Won't Be Enough

The European Union's ReFuelEU Aviation regulation represents one of the bloc's most ambitious attempts to decarbonise a notoriously difficult sector. From January 2025, fuel suppliers at EU airports must blend at least 2% alternative aviation fuels into their kerosene mix, rising to 70% by 2050. It's a bold policy signal that should catalyse billions in clean fuel investment. But recent modelling suggests Brussels may be setting itself up for a climate reckoning.

The arithmetic is sobering. Meeting the 2050 mandate through synthetic e-fuels alone would require 44-64 million tonnes of green hydrogen annually—consuming up to 45% of the EU's projected domestic hydrogen production. That's hydrogen Europe also needs for steel, chemicals, and heavy transport. Aviation would effectively be competing with half the industrial economy for the same constrained resource.

Introducing hydrogen-powered aircraft eases the squeeze somewhat, reducing the sector's hydrogen appetite by up to a quarter. But here's the problem: fleet turnover moves at glacial pace. Even if airlines ordered only hydrogen planes from tomorrow, they'd represent just 10% of intra-European traffic by 2040 and barely 60% by 2070. Wide-body hydrogen aircraft for long-haul routes remain firmly in the conceptual phase. The transition timeline simply doesn't align with climate urgency.

The CO₂ picture looks deceptively encouraging. ReFuelEU compliance could slash aviation's net carbon emissions to roughly a fifth of current levels by 2060. Add hydrogen aircraft and you squeeze out another quarter by mid-century. Technically, if the electricity powering this transformation is genuinely low-carbon, European aviation could approach net-zero CO₂ without offsets—a genuine achievement.

But carbon dioxide represents only part of aviation's climate impact, and arguably not the largest part. Nitrogen oxides and persistent contrails currently drive nearly five times more warming than aviation's CO₂. Hydrogen combustion cuts NOx by around 90%, and synthetic fuels produce less soot, reducing contrail formation. Yet even optimistic deployment scenarios show aviation's temperature contribution rising again after 2060 under high traffic growth.

This exposes the fundamental flaw in Europe's approach: ReFuelEU treats aviation decarbonisation purely as a supply-side challenge. The regulation mandates cleaner fuels but remains conspicuously silent on demand. Analysis by CE Delft suggests European aviation has roughly 2.4 gigatonnes of CO₂ budget remaining to stay within Paris Agreement limits. Both high and low-growth traffic scenarios exhaust this budget by the early 2040s—well before the clean fuel infrastructure matures.

Only a managed decline pathway, reducing demand to 70% of 2019 levels by 2035, keeps cumulative emissions within limits while maintaining consistency with 1.5°C targets. That's the conversation European policymakers seem determined to avoid, despite mounting evidence it's unavoidable.

The policy silence around demand management reflects political reality. Ticket taxes, frequent flyer levies, and airport capacity caps are electoral dynamite in a continent that views cheap flights as a social entitlement. Yet without such measures, ReFuelEU risks becoming an expensive exercise in futility—delivering impressive fuel blend percentages while overshooting climate targets.

The biomass alternative offers no escape hatch. While bio-based sustainable aviation fuels can meet half the mandate until 2030, sustainable supply chains face hard limits from land-use and biodiversity constraints. Biomass might reduce hydrogen requirements, but delivers similar overall climate benefits to e-fuels when replacing equivalent fossil kerosene volumes.

What Europe needs is policy honesty. ReFuelEU should be presented for what it is: a necessary but insufficient first step. The regulation creates vital investment certainty for alternative fuel producers and signals where aviation must eventually arrive. But it cannot, alone, keep European skies within their carbon budget.

The next decade will prove decisive. If Brussels couples fuel mandates with credible demand-side policies—perhaps starting with business jet restrictions or differential pricing that makes short-haul flying genuinely expensive—Europe might chart a realistic path to climate-aligned aviation. Infrastructure investment, carbon pricing, and traffic management must advance in concert.

The alternative is predictable: spectacular success in alternative fuel deployment accompanied by spectacular failure in meeting climate commitments. Europe's aviation sector will boast the world's cleanest fuel mix while its absolute emissions continue destabilising the climate. That would represent policy failure dressed up as environmental leadership—an outcome neither the industry nor the planet can afford.

The technology exists to decarbonise aviation. What's missing is the political courage to acknowledge that cleaner planes flying more often still equals climate breakdown. Until Europe confronts that arithmetic honestly, ReFuelEU will remain an ambitious gamble with disturbingly long odds.