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Whatever happened to geothermal energy production?

  1. Jan 13, 2017 #1

    n01

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    I've become nauseated with the recent obsession with colonizing Mars, mining the moon or asteroids, and spending resources on intermittent power production from wind, solar, and batteries.

    I've looked at numerous sources of energy production and have come to the conclusion that instead of looking to the sky, one ought simply dig deeper.

    The Earths mantle is essentially an inexhaustible source of energy via injecting water for high-pressure steam extraction. Furthermore, we have barely begun mining deep into the Earth core for heavier elements and other resources, which are imperative for economic growth and prosperity. Energy is carbon neutral available 24/7 and there's no need for the expensive and labor intensive production of batteries to store energy. A third issue that gets solved is desalinization of water if there is such a need, which there is. On so many levels this seems like the most cost-effective and cheap and abundant source of energy just lying below our feet.

    I would be interested in getting to know why hasn't the simple issue of drilling holes as deep as possible and extracting energy via heat never taken off?
     
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  3. Jan 13, 2017 #2

    davenn

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    mainly because in most areas, the mantle is well below easy/economical drilling depth

    geothermal sites around the world are mainly located in areas where the crust is very thin ... less than ~ 5km
    so this immediately decreases possible good locations for such generating activities

    The www site gives the top 10 geothermal generating sites around the world

    http://www.power-technology.com/features/feature-top-10-biggest-geothermal-power-plants-in-the-world/ [Broken]


    Dave
     
    Last edited by a moderator: May 8, 2017
  4. Jan 13, 2017 #3

    n01

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    Well, we can build rockets and go to the moon, but can't invest in solving a simple engineering problem of drilling holes deeper. I mean, we have the natural talent and expertise to get the job done (think the multitude of oil/fracking companies in the U.S)...

    Does this simply boil down to the fact that there isn't that much money (incentive) to get the job done? If so, please shoot me.
     
  5. Jan 13, 2017 #4

    davenn

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    what I'm telling you is that it ISN'T simple engineering else it would be getting done all the time

    the deepest borehole drilled only went to a tad over 12 km, that doesn't even make it 1/2 way to the mantle under most continents. And that is why geothermal bores are limited to geothermal regions where the crust is much thinner

    fracking and the likes only goes down a km or so
     
  6. Jan 13, 2017 #5

    n01

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    The case I'm trying to make is that from an economic perspective you get multiple birds with one stone.

    1. Spur investment in novel mining techniques that can go deeper to utilize the heat found at those levels.
    2. With the investments and thus technological and engineering hurdles overcome, have access to resources previously inaccessible, spurring growth.
    3. Provide clean energy that is carbon neutral and virtually limitless.
    4. Utilize facilities to produce desalinized water, possibly lowering costs to those who need it most.
     
  7. Jan 13, 2017 #6

    Vanadium 50

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    Reasons that you want something are not the same as reasons that it is possible.
     
  8. Jan 13, 2017 #7

    n01

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    We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.— John F. Kennedy, May 25, 1961
     
  9. Jan 13, 2017 #8

    russ_watters

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    I think you are missing the point/problem: Even if we assume that the effort will just be "hard" and we can do it if we choose to, it will certainly be fabulously expensive. Kennedy didn't care about Apollo being fabulously expensive because it was a one-time, 'lets just see if we can do it' project. Geothermal power would be a long-term program tied to the economy and the economics matter, if for no other reason than that there are lots of other options that geothermal has to compete with.

    To say it more succinctly: the biggest problem with your idea isn't that you assume it will be easy it is that you assume it will be cheap. It won't be, and that matters.
     
  10. Jan 13, 2017 #9

    n01

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    I see this as saying that there ain't enough profits in geothermal energy to make it a reality. Is that what you are implying?

    I must be missing something here. Geothermal costs are negligible. You don't have to mine the stuff or control it as, say, nuclear reactors. The energy is constant and non-depletable. The only moving parts are just the turbines and we already have some geothermal plants working in the West. The only engineering obstacle is digging deeper holes, does that really sound like a problem as compared to something like putting solar panels in space etc. ?
     
  11. Jan 13, 2017 #10

    berkeman

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  12. Jan 13, 2017 #11

    russ_watters

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    There isn't enough profit (or savings) to make people choose to do it over something cheaper.
    Just like solar power is free, wind power is free and hydroelectric power is free? C'mon, don't be intentionally dense here: they are only free except for the parts that cost a lot of money!

    Geothermal energy is "free" in exactly the same way that gold and oil are "free": They are all sitting there under the ground for anyone to take; all you have to do is dig them up!
     
  13. Jan 13, 2017 #12

    n01

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    How are you deriving that qualification on geothermal being 'fabulously expensive'? Af far as I know, the cost of maintenance and virtual full automation of such a geothermal facility is significantly lower than nuclear. If you consider the long-term costs (maintenance, no need tor transport of materials to facility, labor) would make economic sense in the long run despite possibly high initial costs.

    If digging deep is really that much of a problem, then why not utilize places like Yellowstone where the magma chamber there is 8 km underground.

    Here's my logic in a nutshell:
    Either way, we're gonna have to dig deeper into the Earth's crust to find new sources of materials that any economy needs for growth. There is an absolute comparative advantage over such bombastic ideas of mining the moon or asteroids no matter how low launch costs go down. If, that is true then why not get started earlier than later? Obviously, this will never happen with our entire economy still stuck with oil and natural gas and the special interest groups or if we can extract what we need from the ocean, efficiently.

    Oh, well.
     
  14. Jan 13, 2017 #13

    Bystander

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    ... until you look at "make-up water" for spinning the turbines.
     
  15. Jan 13, 2017 #14

    davenn

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    you are ... they are not negligible

    I see millions upon millions in a geothermal installation like this
    cost of the bores, many 10's of km of pipping large buildings, turbines and generators and the maintenance thereof
    and this is where the energy source is less than 1000m deep

    wairakei1.jpg

    wairakei2.jpg

    wairakei3.jpg


    and that is only a small portion of the overall installation that can be seen

    Dave
     
  16. Jan 14, 2017 #15

    Astronuc

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    What is the basis of such a statement?

    http://geo-energy.org/geo_basics_plant_cost.aspx
    According to this publication, nuclear is not much more expensive than geothermal. Like natural gas-fired or wind plants, one needs many units to provide the same power as a single nuclear unit. That means many turbines, generators and transformers. The infrastructure cost is not negligible.

    From US DOE - https://energy.gov/eere/geothermal/geothermal-faqs

    Geothermal sources are often not in locations where people live, so transmission systems are necessary, same as for nuclear plants that are often built away from metropolitan areas.

    Simply digging deep is not necessarily the answer, and comparing geothermal energy with space exploration (e.g., sending rockets to the moon, or mining asteroids) is not a productive discussion. They represent two very different aspects of human economy. There are plenty of elements available on earth for terrestrial application, while mining the moon or asteroids would support space exploration, not terrestrial projects.

    Desalination is usually done near coastlines, which are not necessarily conveniently located near geothermal sites.

    For some dated numbers of geothermal development/utilization, see - https://www.iea.org/publications/freepublications/publication/Geothermal_Essentials.pdf

    And there is the matter of location of generation (and water), location of load (use) and competing generation, e.g., hydropower
    http://www.usgeothermal.com/About/FAQ.aspx [Broken]
    One must also consider the temperature of the geothermal formation (e.g., 100 to 370°C, or ~ 200 to 700°F).
    http://geo-energy.org/Basics.aspx#directuse

    If one were to simply pump water into a geothermal source, then in addition to steam production, one would also be concerned with the chemical reaction between water and the minerals/rock formation. One could use a different working fluid in a closed loop, but then one has to be concerned with subsequent leaks due to erosion/corrosion over the lifetime of the loop.
     
    Last edited by a moderator: May 8, 2017
  17. Jan 14, 2017 #16

    n01

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    Maybe we're reading two different papers; but, this was the conclusion from the link provided:
    In a comparative analysis between wind and geothermal, geothermal came out on top, given a virtual operational lifespan of 50+ years and I don't think the authors included the additional costs that most renewables ential in regards to energy storage (batteries, molten salt, etc.)

    If location is really that much of an issue, then digging deeper is the only answer. Furthermore, geothermal can recoup the costs of digging deeper via such applications as heating, sewage treatment, and offsetting transmission costs. What's more, you could theoretically retrofit a coal plant's elements into a geothermal setup.

    < Mentor Note -- Post has been edited to remove insults >
     
    Last edited by a moderator: Jan 14, 2017
  18. Jan 14, 2017 #17

    n01

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  19. Jan 20, 2017 #18
    Hi n01,
    Iceland is/was creating a financial model project to sell electricity to Europe using their significant geothermal resources.
    Not sure what happened to project... BUT, looking into that will tell you alot more about current realistic geothermal practices.
    Chk it out. And post what you find back here!
    Miky
     
  20. Jan 21, 2017 #19
    Why not use the thermal vents in the ocean? Put some type of hood over the vent to catch the heat to boil water and run a turbine.
     
  21. Jan 21, 2017 #20

    Astronuc

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    The vents are at such pressure, due to the depth of the ocean, that steam does not form. Rather, the hot water is either subcooled or supercritical liquid.

    https://en.wikipedia.org/wiki/Hydrothermal_vent#Physical_properties

    A turbine would require housing in a lower pressure casing (pressure vessel) to prevent collapse, while maintaining a lower pressure than the surrounding water. Assuming the power conversion was accomplished at the vent sites, then several hundreds or thousands of km of undersea conductors would be needed to get the electrical power to populated areas. Not very economical in most cases.

    http://www.mesa.edu.au/deep_sea/hydrothermal_vents.asp (map).
     
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