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Freshwater (industrial scale) from seawater, on sunlight

  1. Aug 7, 2016 #1
    i have this idea to produce fresh water for farming and all the other uses of fresh water, from seawater, on sunlight, using mostly/only off-the-shelf parts..

    i am currently not able to pursue this idea myself due to financial constraints, so i thought i'd float the idea here looking for some constructive feedback.. i'm also not a mechanical engineer, i have studied software engineering, so i have a couple of specific hurdles with the engineering that i'd like your feedback on..

    it starts with pvc tubing bringing seawater to a desert/climatically-hot area.. the pvc tubing does not need to be raised above ground level but rather be just laid on the ground to preheat the seawater.
    at the conversion site, you'd have multiple evaporation chambers made out of black plastic funnels, one normally upright beneath one inverted (so narrow part pointing straight up) and tied together using black ducktape perhaps.

    problem 1 is maintaining a stable water level in the lower (upright, narrow part of the funnel pointing down) funnels, and bringing new seawater to those lower funnels over terrain that varies in height aswell (potentially for several miles)..

    problem 2 is the condensation of vaporized freshwater from the 2-funnels devices back into liquid form for transportation to a farming area (which is suspect are pentiful), any area that could be farmed if it would receive a stable freshwater supply..

    this idea is copylefted and donated to humanity by me. you are free to implement it entirely on your own and perhaps even turn it into a business where you take a modest percentage of revenue (the food output) to make the thing economically sustainable and interesting-to-scale-up..
     
  2. jcsd
  3. Aug 7, 2016 #2

    mfb

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    No, this idea is over 100 years old, probably over 1000. And there are various technical challenges which don't make it practical on an industrial scale in most places.

    Corrosion is a huge issue, how to get rid of the salt water residue is one, how to pump seawater into the system is one, ...
     
  4. Aug 7, 2016 #3
    Please list all the technical challenges in as detailed a manner as you can, ok.
    I believe this idea to be worth the effort of making it work.
     
  5. Aug 7, 2016 #4

    mfb

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    Various publications and reports did that, you can check those.
    Do you really think such a simple and obvious idea would not have been tested many times? There are not many systems around using it. What does that tell you?
     
  6. Aug 7, 2016 #5

    OmCheeto

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    Yup.
    per wiki
    Solar desalination
    History
    Methods of solar distillation have been employed by humankind for thousands of years. From early Greek mariners to Persian alchemists, this basic technology has been utilized to produce both freshwater and medicinal distillates. Solar stills were in fact the first method used on a large scale to process contaminated water and convert it to a potable form.
    In 1870 the first US patent was granted for a solar distillation device to Norman Wheeler and Walton Evans. Two years later in Las Salinas, Chile, Charles Wilson, a Swedish engineer, began building a direct method solar powered distillation plant to supply freshwater to workers at a saltpeter and silver mine. It operated continuously for 40 years and produced an average of 22.7 m3 of distilled water a day using the effluent from mining operations as its feed water.

    "detailed"? Ummmm..... no.
    Wiki lists a couple of problems: Problems with Thermal Systems

    Plastic pipe:
    Eliminating Corrosion
    GF Piping Systems was called in as a possible source to supply a solution to the plant’s saltwater corrosion problem. GF recommended polyvinylidene fluoride (PVDF) and polyethylene (PE) piping systems as the solutions for eliminating the saltwater corrosion. These thermoplastics are highly resistant to salt solutions...
    Harvest the salt!
    Find a manufacturer who specializes in seawater pumps: Warren

    When in doubt, let someone else solve your problem.
     
  7. Aug 7, 2016 #6

    mfb

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    @OmCheeto: There are solutions to all those issues, sure, but they all increase the costs.
     
  8. Aug 7, 2016 #7
    thanks for the details provided.. i'll certainly look into them within a week and possibly continue this thread
     
  9. Aug 7, 2016 #8

    OmCheeto

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    Well, the title includes the phrase "industrial scale", so I figured money was no object.
    But, as my second reference points out; "The project never received enough funding, and the company was declared insolvent in 2014."
    So, yes. Costs are important.
    I think we covered some cost cutting measures in Ivan's "Algae to the rescue" thread.
    I believe I mentioned that tides can replace pumps. But that somewhat limits the location.
    As I responded

    There are a billion and one "technical challenges". Ain't nobody got time for that.

    And since this isn't a local problem
    I ain't gonna worry about it, no more.
     
  10. Aug 7, 2016 #9
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