Energy is fungible at an efficiency loss. If solar gets cheap enough we'll use it, water, and atmospheric CO2 to synthesize hydrocarbons. At that point your b

Energy is fungible at an efficiency loss. If solar gets cheap enough we'll use it, water, and atmospheric CO2 to synthesize hydrocarbons. At that point your boats and planes are net carbon neutral. It's getting carbon-free energy that cheap that's the challenge. EDIT: I hope the OP wasn't getting downvotes. It was a reasonable thing to worry about.