The electrification of non-propulsion systems has been a continuous evolution of airplanes and helicopters for decades, while the electrification of propulsion systems promises a real revolution. This implies a new way of designing aircraft, their architecture, their aerodynamics, not to mention their operating model.
Current research and innovation projects on the electrification of propulsion promise a profoundly renewed aeronautical landscape in the decades to come. This landscape will be highlighted by a greater diversity in the format and use of aircrafts. This diversity will depend in particular on the degree to which electricity is used as a propulsive energy source.
Hybrid electric propulsion:
Some aircraft will use micro-hybrid technologies. This involves combining current combustion engines with small intelligent electric motors, like the “start & stop” system already common in the automotive world. But in aeronautics, this technology allows the pilot to put one of the two engines on standby during the cruise phase. And when necessary, for example during acceleration, landing or an emergency maneuver, the engine on standby is reactivated at maximum power by an electric motor.
In other words, the hybridization technology will consist in developing more powerful thermoelectric systems, directly involved in the aircraft’s lift and propulsion, in addition to powering its non-propulsive functions.
Hybridization : an alternative to hydrogen
A few months ago, Airbus presented three hydrogen-powered aircraft concepts following the French government’s announcement of a €15 billion support plan for aeronautics in return for the launch of a green hydrogen-powered aircraft by 2035.
However, last February, the aircraft manufacturer also announced that it was working on hybrid electric propulsion technology as part of its plans to reduce CO2 emissions from its airliners. This is because hydrogen could initially only be used on small aircraft due to the problems of storing it in large quantities and filling the tanks, which requires liquefying the hydrogen and transporting its liquid state to the airports. The best option for the future replacement for the 150-seat A320 (Airbus’ best-selling model), which will probably enter service in the 2030s, would be a hybrid electric power solution. Hydrogen is only expected to power such large aircraft at a later time.
To apply the hybridization option, Airbus would use a Daher-Socata TBM 900 turboprop to study distributed propulsion by a standard engine complemented by electric motors mounted on the wings.
100% electric propulsion:
The ultimate step in the process will be 100 percent electric propulsion, in which the combustion engine disappears entirely in favor of a purely electric primary energy source. Projects exploring all these possibilities are multiplying around the world, from established industry players like Safran and Airbus to start-ups. In fact, Wright Electric and its partner EasyJet are aiming to fly a 186-seat electric aircraft by 2030.
However, there are challenges to this type of propulsion. One of the hurdles to overcome is obtaining certification for this type of aircraft, as we would be unable to accept a system in which there is a risk of the batteries catching fire. The 737 MAX tragedies have reminded us of the challenges of aviation safety.