Add this to the list of environmental worries: The generation
of electricity is a highly water-intensive process. It takes
three times as much water to produce the electricity needed for a home,
than the water used in that home.
href="http://www.csmonitor.com/2007/0417/p01s02-wogi.html">Trade-off
looms for arid US regions: water or power?
Water consumed by electric utilities could account for up to 60 percent
of all nonfarm water used in the US by 2030.
face="Helvetica, Arial, sans-serif">Albuquerque, N.M. - The
drive to build more power plants for a growing nation – as
well as the push to use biofuels – is running smack into the
limits of a fundamental resource: water.
Already, a power plant uses three times as much water to provide
electricity to the average household than the household itself uses
through showers, toilets, and the tap. The total water consumed by
electric utilities accounts for 20 percent of all the nonfarm water
consumed in the United States. By 2030, utilities could account for up
to 60 percent of the nonfarm water, because they use water for cooling
and to scrub pollutants.
This water-versus-energy challenge is likely to be most acute in
fast-growing regions of the US, such as the Southeast and the arid
Southwest. Assuming current climate conditions, continued growth in
these regions could eventually require tighter restrictions on water
use, on electricity use, or both during the hottest months, when demand
for both skyrockets, researchers say. Factor in climate change and the
projections look worse. This is prompting utilities to find ways to
alleviate the squeeze...
There is a fair amount of technical detail in the piece, but the bottom
line is this:
face="Helvetica, Arial, sans-serif">In the end, "there is no
single silver bullet" for coping with the projected effects of global
warming, Mr. Jones says. "Renewables will play an important role, but
energy efficiency is the only way you can deal with it without
environmental impacts."
There is research being done at an avid pace, to find various ways to
reduce the water consumption in power plants. No one solution
will work everywhere. But this is another area where good
R&D is needed. It is also an area where the USA could
develop exportable technologies that the rest of the world is going to
need. With the trade imbalance being what it is, this could
help us in more than one way.
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It strikes me that most of the water used for steam generation and cooling could be (and should be) recirculated, requiring only modest replacement. I'm not sure how that applies to scrubbing, but I think some recovery should be possible there as well, probably via fractional distillation which could be at least partially driven by heat exchange from cooling steam.
Well whether it be by the additional cost of water recycling, or an increased charge for the water, it looks like irrespective or some sort of carbon tax, fossil fuel based energy in arid regions is going to be more expensive.
If all costs of producing electricity were factored in, perhaps we would find that solar and wind, especially in arid climates, are not at all cost prohibitive but quite cost effective even in a short timeframe.
It would be interesting to see an evaluation of water consumption for growing biofuels (or crops to produce the fuels). It might appear, that growing the biofuels is much more expensive than it appears to be.
"It strikes me that most of the water used for steam generation and cooling could be (and should be) recirculated, requiring only modest replacement. I'm not sure how that applies to scrubbing, but I think some recovery should be possible there as well, probably via fractional distillation which could be at least partially driven by heat exchange from cooling steam."
Most is (water for steam or cooling needs treatment, and so is recycled as much as possible), but I'm suspecting the losses are evaporation from cooling towers.