Something’s not right here.

Some solar thermal plants heat an oil instead of water. As far as storing heat, water, oil and molten salt are being used. Salts can be heated to over 1000 F and are extremely efficient at storing heat. The salts melt at about 450 F

Solar thermal plants need to cool the vaporized water, so it can condense and be reheated. This is done either with water cooling or air cooling. Air cooling loses some of the efficiency, but has the advantage of not using water in desert conditions. Where water cooling is appropriate, the system can double as a way to purify brackish or polluted water. This could be a big factor, especially for some third world countries like India.
Even when they are cooled by water, the amount required is miniscule when compared with the cooling water required for a nuclear plant.
A must read article on solar thermal is at:
http://www.salon.com/news/feature/2008/04/14/solar_electric_thermal/index.html

This article shows why solar thermal is the best replacement for coal fired plants.

Another good article is at Scientific American. ” A Solar Grand Plan” This proposal advocates using concentrating PV power plants more than solar thermal, which I disagree with,(I think maybe they had people from First Solar on their board, since they emphasize Cadmium Teluride cells) but the overall plan is good and they show the cost analysis of doing this. They envision having a 69% solar powered grid by 2050.
http://www.sciam.com/article.cfm?id=a-solar-grand-plan

Also, Green Wombat has lots of articles on the development of solar thermal, just go to the archives to find them.
http://greenwombat.blogs.fortune.cnn.com/

It should be noted that the application appropriate for these solar farms is large scale. They become much more cost effective when they are over 100 megawatts.
Brightsource has proposals for plants up to 900 megawatts in the Mojave desert.

The three power companies in California have already signed up for 2 gigawatts of solar thermal plants. It’s just the begining.
One gigawatt would power San Francisco, or about 770,000 homes. By comparison, Hoover Dam is about 2 gigwatts. Nuclear plants are usually 1 or 2 gigawatts.
The average coal plant is about 600 megawatts
1000 megawatts = 1 gigawatt