>>1670911By design jet engines are extremely ineficient at very slow speeds when it comes to make thrust, using the apu as a generator (since it alredy does come fitted with a generator) to run an electric engine on the wheels would be far more efficient. (up to 4% fuel saved on average, on an industry where margins are minimal)
The main limitation to early adopters has been upfront cost, airliners will probably only adopt it if it's inbuilt into a new aircraft to maximize lifetime cost savings.
https://www.aviationtoday.com/2019/05/01/electric-taxiing-systems-past-present-possible-future/And the jet is by definition an internal combustion engine, it uses the brayton cycle to burn a fuel air mix that it uses as a working fluid. Something like an steam or a stirling engine isn't an internal combustion engine because the heat sources come externally to it.
