[Firestormalpha]

well there's always nuclear power plants, not 100% clean, and everytime someone builds one someone accuses them of starting a weapons program.

Solar power is already pretty effective.

Fusion I think would be a touch difficult seeing as the only place I've heard of it being a sustained reaction is in the core of the Sun (and the other stars)

And from what I've seen and heard hydrogen powered cars have been a good option for some time now.

Essentially many of the technologies that give you clean energy already exist in an efficient form. Have they been optimized? probably not yet, but put them into action first and reduce the dependence on petroleum then work on perfecting them.