Sustainable Aviation: Hydrogen’s Dual Role in the thriving future of Europe’s skies 

Key Takeaways 

• In the EU, Sustainable Aviation is guided by mandatory sustainable aviation fuel (SAF) targets, starting with 2% sustainable aviation fuel in 2025 and increasing to 70% by 2050, with a growing share coming from synthetic aviation fuels (eSAF). 
• Hydrogen supports Sustainable Aviation in two complementary ways: direct onboard use in future aircraft and indirect use as a feedstock for SAF. 
• eSAF creates near-term hydrogen demand because EU regulation requires increasing shares of hydrogen-derived fuels from 2030 onward. 
• EU policy combines demand and supply measures, including ReFuelEU Aviation and the €720 million first auction of the European Hydrogen Bank. 
• Climate performance in Sustainable Aviation includes both CO₂ and non-CO₂ effects, and hydrogen changes the emissions profile while EU monitoring expands. 
• The period from 2025 to 2050 will determine scale, with milestones in SAF production, hydrogen supply, airport readiness, and aircraft certification. 

Why Hydrogen Matters for Sustainable Aviation 

Sustainable Aviation in Europe is no longer driven by voluntary commitments alone. It is anchored in binding regulation, public funding mechanisms, and aircraft development programs with defined timelines through to 2050. 

Hydrogen supports Sustainable Aviation in two interconnected ways: 

First, it can be used directly onboard the aircraft, either burned in modified turbines or converted into electricity through fuel cells. This pathway aims at eliminating operational CO₂ emissions from the flight itself. 

Second, hydrogen serves as a feedstock for synthetic aviation fuel, often referred to as e-kerosene or eSAF. In this pathway, renewable hydrogen is combined with captured CO₂ to produce a drop-in fuel that can be used in today’s aircraft interchangeably with fossil fuel-derived aircraft fuel. 

These two roles use different timelines but reinforce the same goal: reducing aviation’s climate impact within a structured European policy framework. 

SAF and eSAF: Explaining the differences 

Sustainable aviation fuel, SAF, is a broad category that includes all aviation fuels produced from non-fossil or lower-carbon pathways that meet approved sustainability criteria. This can include advanced biofuels made from waste oils, agricultural residues, or other sustainable biomass, as well as synthetic fuels.  

E-SAF, short for electro-sustainable aviation fuel, is a specific type of SAF produced using renewable electricity. In the e-SAF pathway, renewable power is used to produce hydrogen via electrolysis, and that hydrogen is then combined with captured CO₂ to synthesise a drop-in jet fuel. E-SAF is chemically and physically identical to conventional fossil fuel counterparts and is the most seamless way to cut CO₂ emissions while continuing to use the same aircraft fleet. 

In simple terms, all e-SAF is SAF, but not all SAF is e-SAF. 

The key difference lies in the production route: SAF can be bio-based or synthetic, while e-SAF specifically refers to fuels made from renewable hydrogen and electricity. 

Frequently Asked Questions 

Is Hydrogen the Future of Sustainable Aviation? 

Hydrogen is positioned as a central pillar of Sustainable Aviation in Europe. It supports near-term emissions reduction through synthetic fuels mandated under ReFuelEU Aviation and long-term propulsion innovation through direct hydrogen aircraft. EU policy and funding instruments reinforce this dual pathway. 

What Is the Difference Between Hydrogen-powered Aircraft and E-Kerosene (eSAF)? 

Hydrogen aircraft use liquid hydrogen onboard and require new airframes and infrastructure. E-kerosene is produced using renewable hydrogen and captured CO₂ and can be used in existing aircraft. Both contribute to Sustainable Aviation but operate on different integration timelines. 

How Does ReFuelEU Aviation Affect Airlines and Fuel Suppliers? 

ReFuelEU Aviation requires minimum SAF shares at EU airports, rising from 2% in 2025 to 70% in 2050, including synthetic fuel sub-shares. This creates long-term demand for hydrogen-based fuels within the Sustainable Aviation framework. 

When Could Hydrogen-Powered Commercial Flights Start in Europe? 

Technology demonstrations are underway. Entry into service depends on certification progress, infrastructure readiness, and industrial scale-up. Early commercial operations in the 2030s align with current Sustainable Aviation roadmaps. 

The Two Roles of Hydrogen in Sustainable Aviation 

For Sustainable Aviation in the EU, both pathways are relevant. Synthetic fuels address near-term compliance and fleet-wide impact. Direct hydrogen aircraft address long-term propulsion transformation. 

EU Regulation: Creating a Market for Sustainable Aviation Fuels 

ReFuelEU Aviation is a European Union regulation that requires a gradual increase in the use of sustainable aviation fuels at EU airports. It forms part of the EU’s Fit for 55 climate package and is designed to reduce the climate impact of air transport by shifting away from conventional fossil-based jet fuel.  

Rather than relying on voluntary airline initiatives, the regulation establishes binding obligations for fuel suppliers, creating a structured and predictable pathway for Sustainable Aviation across Europe. 

ReFuelEU Aviation: Targets Through to 2050 

By combining binding demand targets with strict sustainability criteria, including rules for renewable fuels of non-biological origin, ReFuelEU Aviation provides regulatory clarity for investors, fuel producers, and infrastructure developers. It reduces market uncertainty, discourages practices such as fuel tankering*, and aligns aviation fuel supply with EU climate objectives. 
 
* Fuel tankering is an airline operational strategy when an aircraft carries more fuel than is strictly needed for its immediate flight (trip fuel + reserves) to avoid or reduce refuelling at the destination airport. 

From 2030 onward, the regulation creates a measurable pull for hydrogen-based fuels. For project developers, this means hydrogen production assets must be designed to follow EU renewable fuel criteria, including renewable fuel of non-biological origin (RFNBO) requirements. 

Hydrogen that does not meet these criteria will not count toward Sustainable Aviation targets. This distinction shapes project structuring, electricity sourcing strategies, and contracting models. 

Direct Hydrogen Flight: Engineering Implications 

Direct hydrogen propulsion represents a structural change in aircraft architecture. Sustainable Aviation in this context is not limited to fuel switching; it involves rethinking airframe design, propulsion systems, and airport interfaces. 

Hydrogen Combustion vs Hydrogen Fuel Cells 

Two propulsion routes are under active development. 

Hydrogen combustion uses modified gas turbines designed to burn hydrogen instead of kerosene. Operational CO₂ emissions can be eliminated. However, combustor design must address flame characteristics and nitrogen oxide formation. Integration with liquid hydrogen storage systems is essential. 

Hydrogen fuel cell propulsion converts hydrogen into electricity, which powers electric motors driving propulsors. This configuration removes combustion from the propulsion chain and increases efficiency of using the fuel. Airbus has stated that after evaluating both combustion and fuel cell pathways under its ZEROe program, it selected hydrogen fuel cell technology in 2025 as the propulsion method for its future hydrogen aircraft concept. 

The two approaches differ technically and operationally. 

Both approaches are part of the Sustainable Aviation research portfolio in Europe. 

Aircraft Design Implications 

Liquid hydrogen has approximately three times more energy per kilogram than kerosene. This gravimetric advantage explains why hydrogen attracts interest in aviation. However, its lower volumetric energy density means tanks must be larger. 

Instead of fitting fuel within existing wing structures, designers often consider fuselage-integrated tanks. This influences structural layout, center of gravity management, and aerodynamic performance. 

Cryogenic storage might require in some cases, insulated tanks, boil-off management, safety zoning, and revised maintenance protocols. Thermal management also becomes central, particularly in fuel cell architectures where waste heat must be dissipated efficiently. 

These factors demonstrate that direct hydrogen Sustainable Aviation solutions are aircraft programs, not incremental retrofits. 

Certification and Ecosystem Coordination 

Certification pathways are advancing alongside technological development. The Alliance for Zero Emission Aviation, launched in June 2022, was created to prepare the aviation ecosystem for hydrogen and electric aircraft entry into service. 

Its work includes: 

• Infrastructure alignment. 

• Safety and regulatory coordination. 

• Industrial readiness assessments. 

For Sustainable Aviation to progress beyond prototypes, these institutional frameworks are as important as propulsion breakthroughs. 

Hydrogen-to-E-Fuels: Scaling Sustainable Aviation Today 

While hydrogen aircraft mature, hydrogen-derived synthetic fuels provide an immediate integration pathway. 

Power-to-Liquid Process Overview 

Synthetic aviation fuel production typically follows these steps: 

1. Renewable electricity generation. 

2. Electrolysis to produce renewable hydrogen. 

3. Combination of hydrogen with captured CO₂. 

4. Synthesis into hydrocarbons. 

5. Refining aviation-grade fuel. 

This chain links power markets, hydrogen production, carbon capture, and refining. Sustainable Aviation therefore becomes an energy system integration challenge, not only an aviation challenge. 

The International Energy Agency has highlighted that low-emissions of hydrogen and hydrogen-based fuels are especially relevant for sectors reliant on energy-dense fuels, including aviation. 

Cost Drivers and Competitiveness Signals 

The cost of hydrogen-based synthetic fuel depends on multiple variables. Electricity price is typically the dominant factor, followed by electrolyser capital expenditure, plant use rates, and CO₂ sourcing costs. 

Modelling by the International Council on Clean Transportation suggests that a carbon price of around $630 per tonne of CO₂ equivalent could make e-kerosene cost-competitive in 2030 under certain assumptions. This estimate illustrates the scale of policy support needed, while actual outcomes depend on technology learning rates and market conditions. 

The table below summarises major cost levers. 

Within Sustainable Aviation, hydrogen-based fuels move toward competitiveness as both technology costs decline and carbon pricing signals strengthen. 

EU Hydrogen Bank and Supply-Side Signals 

The European Hydrogen Bank’s first auction awarded approximately €720 million to seven renewable hydrogen projects, with six signing grant agreements in October 2024. Projects must begin production within five years. 

This supply-side de-risking mechanism expands renewable hydrogen availability. For Sustainable Aviation, a larger hydrogen supply base reduces upstream constraints and strengthens confidence in synthetic fuel scaling. 

Climate Performance: CO₂ and Beyond 

Sustainable Aviation increasingly addresses full climate impact rather than CO₂ alone. 

European environmental reporting finds aviation climate impact as a combination of CO₂ and non-CO₂ effects, including nitrogen oxides, particulate matter, sulfur oxides, water vapour, and contrail-cirrus formation. 

Hydrogen alters this profile: 

• Operational CO₂ from combustion can be eliminated. 

• Hydrogen combustion produces roughly 2.6 times more water vapour than kerosene combustion. 

• The absence of carbon cuts soot formation. (Soot is a fine, powdery black or brown substance primarily composed of carbon, produced through the incomplete combustion of fuels.) 

EU monitoring frameworks are expanding to include structured non-CO₂ assessment for intra-EEA flights. This broader accounting ensures that Sustainable Aviation solutions are evaluated against comprehensive climate metrics. 

What to Watch Next: 2025–2050 

Sustainable Aviation in Europe is now driven by binding targets. The key question is how quickly industry, infrastructure, and technology can scale to meet them. The period from 2025 to 2050 will determine whether hydrogen and sustainable fuels expand in line with EU requirements. 

2025–2030: Turning Targets into Capacity 

In 2025, the 2% SAF requirement begins. By 2030, the share increases to 6%, including a synthetic fuel sub-share. This is the first point at which hydrogen-based fuels become structurally relevant for compliance. 

During this phase, progress will depend on: 

• Large-scale synthetic SAF plants are reaching the final investment decision. 

• Renewable hydrogen projects following RFNBO rules and entering operation. 

• Long-term supply agreements between airlines and fuel producers. 

• Early hydrogen airport infrastructure pilots. 

This period marks the shift from policy design to measurable production capacity. 

2030–2040: Industrial Scale and Aircraft Readiness 

Between 2030 and 2040, SAF requirements rise to 20% in 2035 and 34% in 2040, with synthetic sub-shares increasing to 5% and 10%. Hydrogen demand linked to Sustainable Aviation grows accordingly. 

Focus areas in this decade include: 

• Scaling renewable hydrogen and power-to-liquid facilities. 

• Advancing hydrogen aircraft for certification under EASA oversight. 

• Expanding airport cryogenic storage and refuelling infrastructure beyond pilot projects. 

By 2040, hydrogen should be embedded both in fuel supply chains and in selected aircraft programs. 

2040–2050: System Integration at Scale 

From 2040 onward, the targets accelerate further. SAF reaches 42% in 2045 and 70% in 2050, with synthetic fuels accounting for 15% and 35%, respectively. At this level, hydrogen-derived fuels are a substantial share of aviation energy use. 

The central questions become whether renewable hydrogen production can meet cross-sector demand, whether hydrogen aircraft operate commercially in defined segments, and whether full climate accounting, including non-CO₂ effects, is integrated into operations. 

By 2050, Sustainable Aviation in Europe will depend on how effectively hydrogen production, fuel synthesis, aircraft technology, and infrastructure have scaled together under the EU’s long-term framework. 

Conclusion 

Sustainable Aviation in Europe is defined by regulation, engineering progress, and capital allocation. Hydrogen connects these dimensions, linking renewable power to fuel production and new propulsion systems. For organisations planning hydrogen production, synthetic fuel integration, or aviation-linked infrastructure, strategic alignment with EU criteria and long-term demand signals is essential. 

Stargate Hydrogen supports renewable hydrogen deployment tailored to European regulatory requirements and industrial scale. To assess how your hydrogen production strategy can contribute to Sustainable Aviation, contact our team of experts and explore solutions designed for performance, compliance, and long-term value creation.