But it isn't efficient, that's the problem! It's grossly inefficient, because of the high capital costs necessary to build a plant, the fact that it takes years and years of lead time to add power to the grid, and the problems of waste disposal and decommissioning plants that have become too radioactive to use.

Plus, as Andrew pointed out, fissionable material is a nonrenewable resource, too, so in the end we will run into one of the same problems with nuclear power that we do with oil.

And finally, it is necessarily a highly centralized source of power requiring control by big utility companies, where renewable energy tends to be more decentralized and places control with small companies and individuals.

All in all, the only good things you can say about nuclear power are that it is a source of energy, however dubious, and that it doesn't contribute to global warming. As I said already, the second point makes it preferable to a coal plant. But it should really be our last resort, not our first choice.