Actually, it turns out that oil is the best source for renewable energy.
The earth manufactures it, the technology for finding, extracting, refining, distributing and burning it is well-defined and advanced.
For some reason, politically, we just don't want to use it.
Try as I might, I can't understand why, other than there's a bunch of sandal-wearing, bicycle riding, patchouli-breathing FM types that think it is a bad thing for some reason.