I found this post on Green Wombat very interesting. Apparently there’s a new type of solar thermal plants that could supply all of the United States’ power needs by covering just 92 by 92 mile square. They work by heating tubes of liquid, and the steam powers turbines.
It’s not a simple solution. That’s a huge area, and the plan would also involve going from AC to DC power.
Of course, this is merely a thought experiment right now. No word as to whether or not it will really happen. But Ausra, the company working on this, expects to have solar storage technology available in 18 months. So we’ll just have to wait and see what happens. I don’t know that a centralized solution really will be the best option.