I wonder if you could use your propeller as a "wind turbine" when landing to recapture some energy? Of fly around in thermals and charge your battery??
Helicopters do this, it's called autorotation. They spin up the rotor while descending and then trade the rotational momentum for a little bit of lift to make a safe landing. It's a tricky maneuver but a part of every heli pilot's training.
I doubt that it's a viable strategy for light aircraft, though. The loss of airspeed from extracting energy out of the wind stream is more dangerous than gliding. Thermals aren't powerful enough to keep a non-glider aircraft in flight as far as I know.
Large aircraft use a small windmill or a ram air turbine to keep hydraulics and electrics up in case of a loss of power, though.
The problem, of course, is that it's just not reliable enough to count on.
And i don't think these kinds of aircrafts have the wing surface etc to be floating around on thermals.
I am not aware of any plane that lands without power outside of an emergency.