Asked for a comment, Andrew Sullivan said that Obama's position was actually the conservative position. "He talked about markets, and that's conservative."
So if somebody wants to build a coal-powered plant, they can; it's just that it will bankrupt them because they're going to be charged a huge sum for all that greenhouse gas that's being emitted.
That will also generate billions of dollars that we can invest in solar, wind, biodiesel and other alternative energy approaches.
It's kind of like the logic that says raising taxes further on cigarettes will not only stop people from smoking, but will generate lots of revenues.