A new aircraft engine design could cut aviation’s climate impact by 75% while burning the same sustainable fuels already entering use. The problem is that aviation contributes to global warming in three ways: CO₂ emissions, nitrogen oxide pollution, and the condensation trails that trap heat high in the atmosphere. Existing engine designs tackle only CO₂, and only partially. This hybrid Water-Enhanced Turbofan (WET) injects water into the combustor to suppress NOx formation, then recovers that water from the exhaust to remove particles that seed contrails. An integrated electric propulsion system adds 25% energy efficiency and allows electric taxiing, reducing noise and local air pollution around airports. If the project succeeds by 2035, short- and medium-range flights could become nearly climate-neutral without requiring new fuel infrastructure. The engine works with drop-in sustainable aviation fuels and could later burn hydrogen. The consortium—including airframers, engine manufacturers, and researchers—aims to validate the core technologies by 2025 and reach a flight-ready ground demonstration by 2030. This would give airlines a practical path toward the European Green Deal’s 2050 climate neutrality target without waiting for entirely new aircraft or fuel systems.
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SWITCH aims to answer the challenge of climate-neutral short-medium range air transport by developing a revolutionary sustainable gas turbine propulsion system – the hybrid Water-Enhanced Turbofan (hybrid WET). It boosts WET technology with hybridization (Electrical Aircraft Propulsion – EAP) to improve energy efficiency by 25% and reduce climate impact by 75% (using net zero-CO2 sustainable aviation fuel, 50% with conventional Jet-A kerosene) compared to a state-of-the-art engine. It is the only concept to significantly reduce all three major warming effects on our climate: CO2 through unmatched efficiency, NOx through water injection in the combustor, and contrails through particle removal and water recovery. Local air quality and noise levels around airports are improved through electric taxiing. The hybrid WET is fully compatible with drop-in SAF and could also be adapted to burn hydrogen. It addresses all climate-notable market segments: Short-, medium- and long-range. The SWITCH project will meet this challenge with a global consortium, through an unprecedented programmatic effort between airframer, engine and system OEMs, key tier 1 suppliers and leading researchers in combustion and propulsion, leveraging relevant and effective synergies between European and national programs. SWITCH will mature the hybrid WET’s two key innovation concepts by 2025: The WET engine to technology readiness level (TRL) 4 through validation of its key enabling technologies and the EAP system to TRL 5 through flight-ready engine ground demonstration of the full propulsion system. Results from SWITCH will reinforce confidence in the climate reduction potential of the hybrid WET propulsion system and form the technological foundation to achieve TRL 6 by 2030. This will enable the innovation to enter into the market by 2035 on a new short-medium range aircraft to significantly reduce aviation’s climate impact towards the European Green Deal’s goal of climate neutrality by 2050.
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