Try the APU (auxilary power unit)

[Cal W]

Go on the internet and search for it. Military choppers and airliners have a, around 30 hp turbine with built in gear reduction out put, spinning the generating system to supply all the power needed in the passanger area.

On the net they also show a fellow that has installed one on a home built plane. Question is, replacement parts and costs , maintainase, maybe nothing that a common person can deal with. But interesting.