Many a fully electric or hybrid project was launched during the last decade – most of them still under development. Compared to their target dates, entering service is delayed for many, some got cancelled, but some have been certified and are in production.
Fully electric propulsion is used, for example, in VTOLs (vertical take-off and landing), which will open up a completely new market segment as air or transport taxis with a low seating capacity of up to 5, but an MTOW (maximum take-off weight) of 2,000 kg and a max range of 300 km.
Another example of a fully electric experimental aircraft is NASA’s X-57 Maxwell, powered by two 400-pound (181 kg) lithium-ion batteries in the plane’s cabin. Although the X-57 Maxwell project is set to conclude by the end of September 2023, its main objective was to gather knowledge about the electric propulsion design and airworthiness of the aircraft. This valuable information has already influenced and will continue to impact the advancement of certification methods for electric propulsion in emerging markets.
Initiatives for large commercial aircraft are focusing on hybrid-electric propulsion systems that enable longer ranges while saving fuel and reducing emissions. However, their development will take more time, and they are unlikely to enter service before 2030. And while they show promise, they won't necessarily catch on, like the E-FanX project initiated by Airbus, Rolls-Royce, and Siemens in 2017. The idea was to replace one of 4 gas turbines with a 2 MW electric motor. The remaining jet engines powered a generator to produce electricity. The project was discontinued in 2020.
In summary, gas jet turbines will remain the standard long-range propulsion system for the foreseeable future. The use of SAF will help to reduce the climate impact to a certain extent. Longer-range aircraft will use hybrid systems. Their fuel consumption is expected to drop by about 25%. However, fully electric short- and medium-range aircraft with low seating capacity are already operational or will be very soon. And although product life cycles of about 30 years will most likely prevent electric or hybrid propulsion systems from being used comprehensively before 2050, experts predict about 45% of all aircraft will at least be hybrid electric by 2035. The technology seems likely to fundamentally change air transportation.