There's a large desal plant in Florida too, it supplies part of the water that I drink. You're right in that it's energy intensive, but at least in our part of the world the largest problem was water quality. There's a lot of biomass floating around in sea water and it means having to constantly repair the filters. I believe there was a big issue with an invasive species of mussels as well that do quite a bit of damage.

http://www.tampabaywater.org/facilities/desalination_plant/i...