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.
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.