Well, if we ARE at peak oil, and the lefties want to go fossil fuel free, the problem will solve itself over time as oil becomes scarce and expensive, and we have to replace it. Of course, if you say no nukes, then a lot of the new electricity will likely be provided by coal. (see Japan)
And if they demand the end of oil production they better be the first ones to peal off all their oil produced clothing and go live naked in an alley eating weeds.