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Geothermal Powerplants

  1. Mar 13, 2007 #1
    Well most ppl thing this is a clean energy, but i'm skeptical about it. What we are doing here is that we are using the heat from the depth of the earth to cool our water for powerplants. If we build thousands of those to use this energy, wouldn't we be cooling our planet? cause otherwise those geothermal sources would be locked by thousands of tons of materials, but we are using fast cooling methods, u may say that its a small percentage and won't affect it! but thats what we used to say about polluting the earth and sea and oceans.....and a lof of other matters.
     
  2. jcsd
  3. Mar 14, 2007 #2

    russ_watters

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    It wouldn't be all that tough to calculate how much heat we'd be talking about...
     
  4. Mar 14, 2007 #3
    yeah but don't u think that it has a degrading effect on the earth's core?
     
  5. Mar 14, 2007 #4
    Your thinking is on the right track, but the tremendous amount of heat contained by the earth and it's core would not significantly be affected by what we are capable of using.

    We are limited on how deep we can go to utilize geothermal energy. What we use comes from much closer to the surface than to the core. Economically we are limited to using geothermal which already comes to, or very close to the surface.

    The U.S. Department of energy even lists geothermal as a renewable energy source. Here are some good links on the topic.

    http://geothermal.marin.org/geoenergy.html

    http://wwwphys.murdoch.edu.au/rise/reslab/resfiles/geo/text.html
     
    Last edited: Mar 14, 2007
  6. Mar 14, 2007 #5
    well what i mean, was that when we used to throw garbage in the oceans, everyone used to say go ahead its a big ocean, now we found out that we were wrong, and its not a big ocean. We all know the conduction of water is large, so it has the ability to cool hot objects in a frightening speed.and in australia they are using a closed loop system to remove heat from the earth's core. We all know that eventually the earth's core is gonna cool by itself, we are making things worse by speeding that up.
     
  7. Mar 15, 2007 #6
    Well, couldn't we use this approach to counteract Global Warming? :surprised
     
  8. Mar 15, 2007 #7
    Yep we did quite a number on polluting the oceans. Although a lot of that pollution came from polluted rivers running into the oceans, dumping dried sewage and hauling the garbage from cities out to sea , was definitely just plain stupid.

    As far as ruining earths resources goes we have hopefully learned our lesson, although I sometimes question that at the rate we are polluting the atmosphere. If we use geothermal with forethought and caution we should be able to extract enormous amounts of energy without causing any significant changes in the temperature of the earths core. There is no current technical process for supplying all of our energy needs with geothermal.

    There are a number of areas globally that use closed loop systems, but none of them that I know of actually extend down to the earth's core. Just ten miles down it is very hot. In a lot of areas, such as along the volcanic rifts of Iceland, the geothermal energy is practically at the surface. I doubt that it hurts anything to cool volcanic activity a bit, since most of this heat ends up being wasted anyway.

    I don't really know the exact figures concerning how much energy over time could be extracted from the earth's core before it would start to cool, but I would hope that someone is taking this into consideration. Apparently you already have and that is a good sign.

    BTW do you have a link to the closed loop system used in Australia?
     
    Last edited: Mar 15, 2007
  9. Mar 15, 2007 #8

    russ_watters

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    Earth's energy budget for geothermal is about 23 terawatts.
    http://en.wikipedia.org/wiki/Earth's_energy_budget

    Humans currently consume energy, from all sources, at a rate of about 3 terawatts (if I converted correctly...). http://energy.cr.usgs.gov/energy/stats_ctry/Stat1.html

    So assuming we could suck all the energy we need out of the mantle, we'd cool the crust a touch, but we'd have virtually zero impact on the Earth's energy balance. All that heat would still be going to the atmosphere and at about the same rate and coming up from the core at about the same rate.

    That said, with our limited technology, geothermal energy is only accessible if it is near the surface (ie, Iceland) in small pockets of magma and is therefore not technically renewable. Iceland will be ok for a while, though:
    http://en.wikipedia.org/wiki/Geothermal_power
     
    Last edited: Mar 15, 2007
  10. Mar 16, 2007 #9
    http://hotrock.anu.edu.au/ i think this website might be interesting.
    As for me i watched it first on Discovery Channel, they passed on the subject briefly but caught my eye.
     
  11. Mar 18, 2007 #10
    with geothermal energy there is a lot more energy being extracted per surface area then is exhausted naturally. instead of absorbing the surface energy, we would effectively be removing the insulation of the earths core and using the heat from the exposed core. the difference is vary small but its there.

    humans have been dumping waste into rivers like they were a magical waste disposal utility for millions of years and only recently have we concluded we are having an impact. geothermal power plants speed up the cooling of the earth's core, but its like the impact humans had on the oceanic ecosystem tens of thousands of years ago. if we converted to geothermal energy, one day we would be thinking "damn our dependence on this energy source! by god its ruining our earth!" but until then we wouldn't be using coal, nuclear, oil, or hydroelectric energies.

    its the same idea with cold fusion. if we got cold fusion going, we would forget about our energy wasting ways until we started to run out of ocean, then we would be really buggered! but hopefully by that time we would be able to suck the water off mars and shoot it back to earth
     
  12. Mar 18, 2007 #11

    Astronuc

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    Russ nailed it.

    The resource is limited to those areas near the surface. At the moment, the geothermal energy IS dumped directly into the environment - e.g. volcanos (and their associated geothermal zones) like St. Helens, Merapi, Ubinas, Tungurahua, Muana Loa and Mauna Kea, and Stromboli, to name a few.

    http://en.wikipedia.org/wiki/Volcano

    Many volcanos are associated with subduction zones at the intersections of tectonic plates, and those show no signs of slowing down.

    The mid-Atlantic ridge is a great example of an area where the earth's geothermal energy is directly released into the oceans.
    http://en.wikipedia.org/wiki/Mid-Atlantic_Ridge

    http://en.wikipedia.org/wiki/Mid-ocean_ridge

    http://en.wikipedia.org/wiki/Seafloor_spreading

    The Wikipedia link cited by Russ shows the countries with significant geothermal programs. It makes sense in those areas where populations sit astride active geothermal areas.
     
  13. Mar 19, 2007 #12

    russ_watters

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    It is quite easy to calculate the effects of both and see that the two are not at all analagous.
    The supply of water on earth is so large it is impossible to calculate how many thousands or millions of years (it depends entirely on our growth projections) we could use it without depleting our oceans.
     
  14. Mar 19, 2007 #13
    Any possibility that an increase geothermal activity could be contributing to the global warming cycle we are supposedly having?
     
  15. Mar 19, 2007 #14
    in my opinion our strive for power no matter what it is will cost the planet warming no matter were it comes from. for example if we take the sun's energy to use it on earth, we are using energy that otherwise might get reflected back to the universe we are trapping it inside our planet.
     
  16. Mar 19, 2007 #15

    russ_watters

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    The sun imparts on the earth 174,000 terawatts of energy and we currently use, from all sources, 3. That's 1/1000th of a percent. I wouldn't be worried about humans having a significant direct impact on the Earth's energy balance.

    The two things we can change are the greenhouse effect and earth's albedo.
     
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