Scientists from China’s Northwestern Polytechnical University and the Chinese University of Hong Kong have presented a concept for an innovative hybrid engine for wide-body aircraft. The new propulsion system combines a gas turbine and high-temperature hydrogen fuel cells. If successfully implemented, the engine will increase flight duration without refueling to 17 hours and completely eliminate CO₂ emissions.
The need for electrification in aviation is driven by the growing share of this industry in global carbon dioxide emissions. Kerosene-fueled jet engines remain the biggest source of pollution. However, fully electric battery-powered aircraft are currently an impossibility: batteries are too heavy and do not provide the required range. Hydrogen fuel cells are much more efficient, but they require a complex storage system and cannot always handle the load during critical phases, such as takeoff.
The Chinese researchers have proposed a compromise: integrating a high-temperature proton-exchange fuel cell into a turbofan engine. This means creating an engine that can operate in two modes. A hybrid mode is activated during takeoff and climb: the gas turbine and fuel cells turn on at the same time to deliver maximum power. At cruising speed, the system switches to electric mode, where the fuel cells perform most of the work.
To test their hypothesis, the scientists built a detailed mathematical model of the engine and the aircraft’s entire power system. The calculations covered aerodynamics, fuel cell operation and processes occurring in cryogenic tanks filled with liquid hydrogen. The model allowed the scientists to track how the system’s performance changes at different speeds, altitudes and loads. They paid particular attention to fuel storage: since liquid hydrogen requires a much larger volume than kerosene, the researchers considered extending the fuselage to accommodate additional cryogenic tanks.
The results were impressive. At cruising speed, specific fuel consumption was 12.6% lower than that of a traditional turbofan, and when throttled, thrust increased by 10%.
However, the most unexpected results had to do with the use of hydrogen. According to calculations, the aircraft could switch entirely to hydrogen fuel if the fuselage were to be extended by 20%. Such a transition would mean a complete elimination of CO₂ emissions, which currently exceed 301 tons per flight. The new engine will also reduce the aircraft’s weight by almost 97 tons and increase its flight endurance to over 17 hours without refueling, which is 20% longer than that of a conventional plane.
The researchers are confident that the hybrid engine concept could be implemented in the very near future. At the same time, they suggest viewing the project itself as a transitional step: potentially, these technologies could form the basis for the creation of fully hydrogen-powered long-haul aircraft.
