Having discussed some similar implications for the grandiose solar plans in South Africa, here's a snippet from an interview with Bright Source Energy CEO, John Woolard. Talking to Yale Environment 360, he discusses the company's experiences from building solar-thermal plants in California's parched Mojave Desert:
e360: BrightSource’s Ivanpah project is not only the first large-scale solar thermal project to break ground, it is the first to deploy a new power tower technology. Why is that significant?
Woolard: [snip] The big [problem] is water. What is the world going to look like over the next 20, 30, 40 years? Water in the desert is going to become a much more challenging proposition. So we’ve gotten water usage down to a minimum — the lowest of anybody in the world, basically.
e360: It seems that one thing BrightSource did that avoided a lot of controversy was the water issue. You chose to use “dry” cooling, which uses substantially less water than “wet” cooling.
Woolard: Best decision we ever made as a company. We were the only one that did it early. The fact that we’re doing it has forced others to do it. If you use 2,000 or 3,000 acre-feet of water [the equivalent of nearly 1 billion gallons] in the desert on an annual basis, that’s obscene.
We’re providing power for 150,000 homes, and we’re using water for 300 homes. That’s as water-efficient as anything you can do. Fossil plants still use wet cooling and everybody ought to know that. That needs to change. It ought to be a level playing field. It shouldn’t just be renewables that do this. Energy and water are so inextricably linked.
Clearly, the 150,000 homes vs 300 homes stat is a tremendously impressive trade-off for anyone concerned about water scarcity.
I'm too lazy to look it up now I can't comment with absolute certainty, but I'm pretty sure these plants will be tapping groundwater for their water needs. Further, I guess Woolard's claim about about other companies being forced to adopt dry cooling is down to direct quantity regulation than any market mechanism... I wonder how their cost figures are lining up?
For the record, according to the US Department of Energy:
Analyses indicate that the use of either direct or indirect dry cooling can eliminate over 90% of the water consumed in a water-cooled concentrating solar power plant. However, a combination of a reduction in power output and the added cost of the air cooling equipment is estimated to add roughly 2 to 10% to the cost of generating electricity, depending on the plant location and other assumptions. [Editors Note: From what I've read elsewhere, I think the figure ought generally to be closer to 10% than 2%...]THOUGHT FOR THE DAY: Using less water can increase costs, but not as much as running out of water.