Of course they can't. Nuclear is about the only viable way currently, but "greenies" won't have that. I think eventually they'll have to accept it as well the climate skeptics. I certainly hope solar comes up from the rear and surprises me, but unless we have a 100x breakthrough in energy storage (batteries or something more exotic) I don't see it happening. I guess a break through in solar->biofuel energy conversion might also be sufficient for it to replace fossil fuels completely.