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Question about using the sea or earth as a electricity producer

  1. Sep 14, 2013 #1
    Hi!
    I have been told that despite the different temperature between the surface and the earth is different we cant use it to produce electricity by using the laws of thermodynamics .. shy isn't possible ?
     
  2. jcsd
  3. Sep 14, 2013 #2

    Pythagorean

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    It is possible, it's called geothermal power. It's not considered sustainable, though.
     
  4. Sep 14, 2013 #3

    AlephZero

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    Really? I guess nobody told the 24 countries that are already using it. (Or about 70 countries, if you include geothermal heating as well as electricity generation)

    There are some geothermal heating systems in the UK that have been running for more than 1000 years already. Doesn't that count as "sustainable"?
     
  5. Sep 14, 2013 #4

    Pythagorean

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    I guess the technical nomenclature is not "renewable".
     
  6. Sep 14, 2013 #5

    Pythagorean

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    But still, depending on how you define sustainability, and to what threshold you hold environmental impact, you might argue that the exhaustion of local heat budgets is not sustainable. It may be case-by-case too. Exhausting a particular local thermal supply might have impact on permafrost in the area which affects habitat, while other thermal supplies are relatively infinite compared to human energy consumption.
     
  7. Sep 14, 2013 #6

    davenn

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    its totally renewable ... its being constantly renewed by the natural processes in the earth

    for where a number of the geothermal power stations are, none of the above is really applicable

    take the geothermal power generation in Wairakei in the upper North Island of New Zealand. The geothermal heat/steam is going to be naturally released into the local surrounds regardless of if it is captured for power generation or not. Its been "pumping" superheated water/steam out of the ground long before man was around to worry about it and will be still doing so long after we are all gone

    attachment.php?attachmentid=61832&stc=1&d=1379216781.jpg

    Gosh ... its been a long time since I last visited there

    cheers
    Dave
     

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  8. Sep 14, 2013 #7

    davenn

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    radioactive8

    looking back at your original question ... it was pretty unclear what you were really trying to define
    Tho your thread title was a little more to the point

    You do know the sea is used in at least a couple of places to generate electric power ?
    They ( the countries involved) use the flow of the tides to turn turbines that then turn generators

    Is there some other specific form of generation other than tides or geothermal that you were wanting to know about ?

    Dave
     
  9. Sep 15, 2013 #8

    Bobbywhy

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    This is a patent for a system that does not use temperature differences to generate power, but does use tidal power of the sea, certainly a renewable energy source.

    “Piezoelectric generation of electrical power from surface waves on bodies of water using suspended weighted members”
    US 5578889 A
    https://www.google.com/patents/US5578889
     
  10. Sep 15, 2013 #9

    Borek

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    There were pilot installations made that used the temperature gradient between surface and deep sea waters to run the power plant. Main problem was the small temperature difference between the heat source and the heat sink (something like 20 K).
     
  11. Sep 15, 2013 #10

    Pythagorean

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    "Totally" is too strong, especially given your justification "constantly renewed".

    Globally, it's definitely not the case... (the earth's core is cooling over time). However, heat extraction takes very little heat compared to the total that for practical (political and commercial) reasons, many people use the word renewable (though still not technically renewable in academic terms) and that's fine with me.

    Locally, on the other hand, it can go either way depending on the local heat budget. "The Geysers" (the largest geothermal plant in the world) is perhaps the most well-known example of local depletion (thought to be caused by human extraction):

    http://onlinelibrary.wiley.com/doi/10.1029/2001JB000638/abstract
     
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