Electric self-launching gliders have been around for years–and they WORK.
That doesn’t mean that technology works in heavier, multi-passenger trainers. Self-launching gliders calculate their range in FEET–most have 6 to 9 thousand feet of climb capability–only a few minutes. Launch and climb to 3000 feet–find a thermal, and have a great time. Lose lift and getting low? Climb another couple of thousand feet–you now have 1-4000’ of climb in reserve.
That’s for a very efficient single place glider of 40 or 50 to one glide efficiency–operating at best L/D–hardly a cross country cruiser. Many people pin their hopes on “better battery efficiency”–yet most of that has already happened, and it gets harder and harder to exact higher percentage of improvements year by year. People USED to pine for perpetual motion–but over 100 years later, the theory still hasn’t worked.