JAN 31

The biggest desalination plant in North America just opened in Tampa, Florida, and is expected to provide 10% of the city’s 2.4 million inhabitants with fresh water. A plant twice the size has now been contracted for Southern California.

Which is good, because we’ve been guzzling our aquifers like petroleum. We’re using our aquifers at a rate that far exceeds their ability to replenish themselves –which leads to land instability and broken links between river/aquifer recharge cycles. Never mind questionable water security for us.

So why has there been a drought of desalination plants in North America until now? For the same reason Arizona isn’t covered in solar panels yet.

Let’s be real here – burning coal to boil fresh water away from seawater (thermal desalination) or using high pressure to squish salt out of seawater through selective membranes (reverse osmosis) are both more expensive and energy-intensive than digging a hole.

The Spanish company Acciona Agua, responsible for the two North American plants, has been working on increasing the efficiency of the reverse osmosis process. The plant currently running in Tampa will sell water for 1,100 dollars an acre-foot (enough for a family of four for one year), but the planned plant in California, because of rapid improvements in the technology, will sell water for only 950 dollars an acre-foot. Water currently goes for 700 dollars an acre-foot in Carlsbad.

And desalination technology continues to evolve, with Abu Dhabi recently touting plans for a solar-powered thermal desalination plant. Now that's something we can really get behind.

Although reducing the drain on our aquifers would be a wise thing to do, the environmental impacts of injecting the salt back into the ocean (which is generally what happens with desalination plants) need more research before this particular process can be thought of as “green.” In any case, the simplest, cheapest, and greenest option will always be to create a society that uses less water. Hopefully we'll move forward on that front as well.

Via the Wall Street Journal and Cleantech.com

Comments (15)

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Desalinization and Renewable Energy are
written by Tim, January 31, 2008

As the ideal spot for these plants is generally oceanside and such locales often have some of the most consistent winds, it seems that the two are made for each other. Throw some solar in and you've got a virtual water factory, albeit, an expensive one.

The Achilles heel does seem to be the inordinate amount of salt that is put back in the ocean. Does it have to go back in the ocean?

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Good idea, but...
written by Emily Marshall, January 31, 2008

couldn't we simply use less water? Xeriscaping, shorter showers, etc.? The oceans are vast, but I hate to treat them like just another resource to be tapped and depleted.

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sell the salt?
written by bob, January 31, 2008

I would think that throwing it back into the ocean is the last thing they want to do.
Couldn't they sell the salt to recoup some of the money?
There's got to be all sorts of market potential for "'green' sea salt" that's not produced by oppressed lower-class salt farmers.

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...
written by EV, February 01, 2008

The oceans are vast, but I hate to treat them like just another resource to be tapped and depleted.

If you believe we could deplete the oceans, I've got a perpetual motion machine to sell you.

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...
written by Ken Roberts, February 01, 2008

Lol @ the perpetual motion comment.

Water desalination does seem to be the way to go. Replacing the salt taken out of the water is probably also the right thing to do... because otherwise you will slowly desalinate the oceans. The water will of course be replaced with natural rainfall.

However, it is important to make sure the salt isn't put back into the ocean in too concentrated of a manner.

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Desalination can't add that much salt...
written by Airmon, February 01, 2008

Evaporation IS desalination. The sun already desalinates trillions of gallons every day, leaving the salt behind.

http://earthobservatory.nasa.gov/Library/Water/water_2.html

Annual Evaporation on Earth:495,000 cubic Kilometers

http://www.sciencedaily.com/releases/2003/12/031218075158.htm

Percent that comes from the oceans:86%

There's a LOT of natural desalination already.

According to google calculator, one cubic kilometer is 2.64172051 × 10^11 US gallons. I think that's 264 Billion gallons.

The Tampa plant desalinates 25million gallons per day, so we'd have to make about 11 thousand such plants to desalinate one thousandth of what the sun does.

AND that water isn't gone, it's just back into the cycle and head for the oceans again to be re-united with the salt.

I'm more worried about the fuel burned in desalination plants that are not powered with renewable energy.

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...
written by Angelo, February 01, 2008

Doesn't it make sense to put it back into the oceans? Billions of gallons of fresh water are being melting at the poles and poured into the oceans and diluting the salt content. Might as well put it back into the oceans to compensate.

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fish-facts
written by James Staunton, February 01, 2008

Another issue that I think was discussed here on Ecogeek was that desalination plants can lead to the destruction of lots of fish, but not necessarily so. I read of a plant in Australia that had worked out a slow extraction system that fish can easily swim out of, and thus not get trapped and killed. I hope that is a part of the new plants. We are already stressing the ocean life ecosystem to the max as it is.

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Aussie info
written by James Staunton, February 01, 2008

I found that source for info on the Aussie desalination plant at NPR: www.npr.org/templates/story/st...d=11134967
Its a great read/listen about a well thought out plant. Using wind power, fish-friendly technology, and from plant to tap in about one half hour processing. Impressive.

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abu dhabi plant
written by chuck, February 01, 2008

today on CNN the people there are buying license plates for millions of dollars because they what the lowest plate number. So over there they dream it they pay for it. Nothing hurts their pockets over there. "Dollars" mean noting to them.

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...
written by RhapsodyInGlue, February 02, 2008

Long Beach is developing a new desalination technology. It is supposed to reduce energy requirements. Also... it goes under the sea floor to both extract and then reinject the concentrated salt water. This means no fish lost to intake and reduces the effects of the effluent. I just about used the typo "affluent"... that would have been an ironic slip given that desal plants have got to be one of the most prominent technological monuments to affluence. One of the plants they built here in Southern Cal adds in minerals to the water to exactly duplicate the flavor of Perrier or Fiji or some such bottled water.

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Political changes
written by Kevin Wright, February 02, 2008

I hope that before we all jump on the de-sal bandwagon we can all pause a minute to think what implications the ability to cheaply de-salinate water means. It means irrigation in the Sahara, Australia, and southwestern USA causing massive shifts in farming and grazing structures that will ultimately lead to increased violence in the less stable areas. It means farmers in the midwestern USA, Europe, and Asia being unable to compete in a global market and it means total change to entire ecosystems that are otherwise untouchable by man. This is not a good thing.

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...
written by Mike Jones, April 11, 2008

I understand what K.W. is saying, but if we can create more livable conditions in other parts of the world, maybe it will stop some of the immigration to the United States. It may give people some drinking water, food and a bath. I myself, don't consider that a bad thing.

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greenie
written by Liam O'Brien, September 09, 2008

i'm not a greenie but the destruction that these cause to the enviroment is ridiculous. The death of the great barrier reef will be accelerated by at least ten years
enough said

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written by Andrew Humphries, May 03, 2009

I think de-salination plants are more of a social indicator than an answer to our increasingly scary water reserves. I have not heard any one in the comments mention how water entering the ocean goes through EXTENSIVE salination on it's way through any country, as farmers use it for irrigation. Infact that would be the reason for our plant in Yuma, Arizona... An old water agreement with Mexico (don't hear that mentioned much, eh?). Where we need to start is massive restructuring of our agriculture and living standards.. We need to invest in vertical farming, which offers a closed water cycle, utilizing brackish water, and recycling it through precipitation.

If anyone has input on this topic or wants to talk about it email me at \n This e-mail address is being protected from spambots. You need JavaScript enabled to view it '> This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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