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posted by Cactus on Monday February 17 2014, @07:01PM   Printer-friendly
from the It's-getting-hot-in-here dept.
similar_name writes:

As part of a project developed by San Francisco area start-up WaterFX, a giant solar receiver in Firebaugh, CA, rotates to track the sun and capture its energy. The 377-foot array, however, does not generate electricity, but instead creates heat used to desalinate water. The goal is to tap the abundant, if contaminated, resource in this parched region: the billions of gallons of water that lie just below the surface.

The water is tainted with toxic levels of salt, selenium and other heavy metals that wash down from the nearby Panoche foothills, and is so polluted that it must be constantly drained to keep it from poisoning crops. This, coupled with the record-breaking drought that California is facing means that irrigation costs are going to double or triple as farms are forced to buy water on the spot market.

"Food prices are going to go up, absolutely", said Dennis Falaschi, manager of the Panoche Water District. "This year, farmers in the Panoche district will receive no water. Last year, they received only 20 percent of their allocation", Mr. Falaschi said. In 2012, the allocation was 40 percent. Farmers elsewhere who rely on the State Water Project to irrigate 750,000 acres of farmland will also receive no water in 2014.

 
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  • (Score: 2, Insightful) by ArhcAngel on Monday February 17 2014, @07:10PM

    by ArhcAngel (654) on Monday February 17 2014, @07:10PM (#953)

    If you are generating heat to desalinate the water presumably by turning it into steam to separate it from the salt why couldn't you also generate electricity by having the steam turn a turbine?

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  • (Score: 5, Informative) by dx3bydt3 on Monday February 17 2014, @07:36PM

    by dx3bydt3 (82) on Monday February 17 2014, @07:36PM (#980)

    Doing both would be possible, but not as effective for producing the maximum quantity of clean water. All the energy extracted by the turbine could have been devoted to converting more water to steam. In order to get energy out of a turbine you have to add that much energy to superheat the steam, if that energy was instead devoted to making more steam, you'd get more clean water in the end.

  • (Score: 3, Informative) by Anonymous Coward on Monday February 17 2014, @07:59PM

    by Anonymous Coward on Monday February 17 2014, @07:59PM (#1008)

    To generate electricity from a gas turbine, the water needs to be heated to well above the boiling point, otherwise water will condense on the blades of the turbines and cause huge corrosion problems. In any situation where you have water that is already very hot, you can install some additional equipment to heat it enough for use in a steam turbine, but the additional expense is not always worthwhile.

    • (Score: 3, Interesting) by sl4shd0rk on Monday February 17 2014, @08:02PM

      by sl4shd0rk (613) on Monday February 17 2014, @08:02PM (#1012)

      Seems to be working for these guys*. "The boilers superheat steam to temperatures of up to 550° C (over 1,000° F), which drives standard turbines to generate electricity."

      * - http://www.gizmag.com/ivanpah-fully-operational/30 862/ [gizmag.com]

      • (Score: 3, Interesting) by VLM on Monday February 17 2014, @08:46PM

        by VLM (445) Subscriber Badge on Monday February 17 2014, @08:46PM (#1059)

        The problem is their future plant is only generating about a million bucks in water revenue per year, its really a very small plant, and high pressure boilers and turbines don't scale well to small size. So maybe 2 or 4 generations in the future, maybe if they successfully expand by a factor of ten each generation of plant...

        In the long run it is probably a good idea for a future much larger plant.

  • (Score: 3, Informative) by dr zim on Monday February 17 2014, @08:57PM

    by dr zim (748) on Monday February 17 2014, @08:57PM (#1069)

    The amount of heat produced is finite. Heat is removed from the water when it turns a turbine or when it is distilled. The water would be too cold to run either process efficiently if you tried to run both with the same water without another trip through a heater in between.

    • (Score: 1) by ArhcAngel on Monday February 17 2014, @09:51PM

      by ArhcAngel (654) on Monday February 17 2014, @09:51PM (#1109)

      Steam rises. If the reservoir of the resultant clean water is higher than the turbine there is no need for the heated water (steam) to be the power source but the force of gravity. The reservoir could be expelled after sunset to generate the electricity. Gravity is going to pull the water down at some point anyway.

    • (Score: 0) by Anonymous Coward on Wednesday February 19 2014, @06:37AM

      by Anonymous Coward on Wednesday February 19 2014, @06:37AM (#2191)

      > The amount of heat produced is finite.

      Really? Are you sure it's not infinite..?

      • (Score: 1) by dr zim on Friday April 04 2014, @04:17PM

        by dr zim (748) on Friday April 04 2014, @04:17PM (#26263)

        Yes. I'm sure.