Does anyone recognize this story?
Starts in space as a military (dictator) ship gets energy from a sun/nova? When they return to the moon base (a prison) years later. It is deserted. Everyone seems to have left in a planned, slow manner, as thought it just was no longer needed.
When they get to Earth, the cities are also deserted. Everyone seems to live a rural life. A prisoner had invented cheap energy from just a few coils of wire. It transformed the way of life. Son of the inventor? is given more time to adjust. His father created the library system.
It may have been a short story, from the 60's or 70's