Until today, the only person I had heard raise this issue has been Richard Doctor of Argonne National Laboratory. In a talk I saw him give a couple of years ago, he pointed out that increasing water supply takes energy, and increasing energy supply takes water, so that the once demand reaches a certain point one can't treat the problems separately.
It turns out I should have asked the question as it would have been a real softball pitch for Webber. He has written an article on the subject [link to abstract only; article is behind a pay wall] appearing in Scientific American. (While it lasts: here is a scan of the text.)
This raises a question which I did not put to Richard nor to Michael Webber but which has been puzzling me. Webber's article makes it explicit:
We cannot build more power plants without realizing that they impinge on our freshwater supplies. And we cannot build more water delivery and cleaning facilities without driving up energy demand. Solving the dilemma requires new national policies that integrate energy and water solutions and innovative technologies that help to boost one resource without draining the other.So here's my question: why do power plants require fresh water? Is the dominant purpose of water not cooling? If not, why is water such a big issue? On the other hand, if cooling and quenching and thermal conduction is the issue, why use precious freshwater instead of sea water?
I note that Austin Energy's part-owned nukes are on the seashore. Of course, there is sea level rise to contend with... Yikes!
I suppose that renewable energy (except biofuel) doesn't require significant water in operations. (Capital costs aside.) Isn't this a strong argument for wind and solar? Why aren't they making it?
Note, the following appears in an information-poor infographic (that doesn't make it into the scanned text) in Webber's article:
Water Required to Generate One MW-hr
- Gas/Steam: 7,400-20,000 gallons
- Coal or Oil: 21,000-50,000 gallons
- Nuclear: 25,000-60,000 gallons
Another argument for natural gas rather than nuclear as the bridge to renewables.
Drop the thousands to convert into the easier to think about KW-hr, which is about the draw from watching a big screen TV for an evening. That would be, depending where you live, between 7 and 60 gallons. (25 to 225 liters). As much as a bathtub's worth on the high side.
So anyway. Is sea water usable instead of fresh water in power plants?