Dealing with Drought (water usage by power plants)

[OKIsItJustMe]

http://blogs.tnr.com/tnr/blogs/the_plank/archive/2007/11/13/living-with-drought.aspx

13.11.2007

Dealing with Drought

It's kind of talking-pointy, but Daniel Weiss and Zoe Brown have a nice analysis of the ongoing droughts in both the Southeast and Southwest. Beyond flogging the usual (sensible!) conservation measures, they also make the good point that energy use is a major culprit here:

Power plants are voracious water users. Nuclear plants use 830 gallons of water per megawatt hour, and coal plants are right behind at 750 gallons per megawatt hour. If current power generation and energy demand trends continue, power plants will use 7.3 billion gallons a day by 2030. The Department of Energy reports that this equals all U.S. water consumption a decade ago.

The Atlanta Journal-Constitution caught onto this a few weeks ago, arguing that, seeing as how Atlanta's Lake Lanier is drying up, maybe it wasn't such a keen idea for the state to grant permits for a new coal plant that will consume "nearly 20 million gallons of water a day" from the Chattahoochee River, "putting an additional strain on metro Atlanta's major source of drinking water." (There's also that whole global warming thing, which is only going to dry out the region further.)

Conversely, wind and solar power use little water. But many states in the Southeast have strongly opposed renewable energy mandates—claiming that they can't live without coal. Georgia Governor Sonny Perdue commissioned an energy task force last year that, in the end, recommended a big push toward renewable power, but that proposal's now gathering dust in a filing cabinet. I wonder, though—if the AJC's any indication—if the water crisis could finally prompt folks to rethink their energy stance. (OK, more likely, they'll just conjure up a way to cool power plants without using so much water, but one can always hope...)

--Bradford Plumer

[Massacure]

1. That is what cooling towers are for.

Wikipedia has an examples of a 700 MW coal fired power plant. One with a cooling tower circulates about 71,600 cubic metres an hour with about 5% of that needing to be replenished. One without a cooling tower requires about 100,000 cubic meters an hour.

[XemaSab]

2. I smell a rat...

My understanding of the "use" of water by power plants is that it's more like "using" water to take a shower, and notsomuch like "using" water on your lawn.

It pretty much goes in one end and out the other without much loss, no? :shrug:

Oh, and on edit, solar thermal plants USE a shitload of water to wash the mirrors off with. So much for all the solar thermal in the mojave desert. :P

[OKIsItJustMe]

3. Those figures seem about right (so far as I can tell)

Most of the losses appear to be in the cooling tower.

http://www.netl.doe.gov/technologies/coalpower/gasification/pubs/pdf/WaterReport_IGCC_Final_August2005.pdf

Power Plant Water Usage and Loss Study

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