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When will mining seawater for elements be affordable?

  1. Sep 23, 2017 #1
    So, I was wondering when will mining seawater for minerals be affordable. The whole process seems very energy intensive to do. Will it ever be a reality one day where we see tritium and deuterium mined alongside lithium and other important elements?

    I've read somewhere that there are enough tritium and deuterium in the seas to power humanity for many thousands of years.

    Why isn't this a reality already?
     
  2. jcsd
  3. Sep 23, 2017 #2

    berkeman

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    That would be in the context of having viable nuclear fusion reactors. Are you familiar with the state of the research into such reactors? If not, you can learn a lot about them in the PF Nuclear Engineering forum (shameless plug...). :smile:
     
  4. Sep 23, 2017 #3
    Hi, berkeman.

    I am only aware of some unique fusion tech currently being developed. Such as Polywell and DPF (Dense Plasma Focus). The efforts being made by Lawrenceville nuclear fusion are quite promising and seem to be the most economical of the bunch if they can ever get enough funding to make the technology a reality. My understanding is superficial and might even be against the forums guideline policy of discussing unproven fusion techniques.

    But, my question is still relevant even if the goal of extracting elements from seawater (such a Uranium or other high-value natural elements, which there are tons in seawater also). The economics of the matter is what interests me, with the amount of energy needed to make it economical being the limiting factor or some better extraction methods (graphene as a filter?). It just seems farfetched or strange that we are seriously contemplating going to asteroids for elements instead of trying to economically extract it right off the seaboard.

    Any input much appreciated.
     
  5. Sep 23, 2017 #4
    Tritium? There is not high demand for it - and a large part of existing demand is for nuclear weapons; not a use that I think should be encouraged.

    I suggest the means for extracting it from sea water is not the technological development of importance.
     
  6. Sep 23, 2017 #5

    berkeman

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    Yes, the fusion technologies that you mention are not familiar to me, and may well not be mainstream. Thanks for being sensitive to that.
    This part of your question is still valid, and I look forward to reading the responses... :smile:
     
  7. Sep 23, 2017 #6

    berkeman

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    This has already been addressed, and is no longer the question that the OP would like addressed.
     
  8. Sep 23, 2017 #7
    Although more of a secondary point and rather hyperbole, I find it to be a valid argument possibly for some measures to control what elements are extracted and what elements aren't. It could limit the widespread adoption of seawater extraction of natural elements, unfortunately.
     
  9. Sep 23, 2017 #8
    Just some interesting information about the amount of uranium in seawater.

    From: https://www.ornl.gov/news/advances-extracting-uranium-seawater-announced-special-issue

    I don't know the rate at which uranium is replenished; but, some tech outlets say that the rate at which uranium is replenished is on par or exceeds extraction rates (demand vs supply). Hurray?

    EDIT: The question still is when will all this become economically viable?
     
    Last edited: Sep 23, 2017
  10. Sep 23, 2017 #9

    Drakkith

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    I'm not sure anyone can answer that. It's a bit like predicting the future. Perhaps the best we can say is that it will become economically viable when cheaper methods no longer work or the demand for something becomes high enough and there are no viable alternatives to seawater mining.
     
  11. Sep 23, 2017 #10
    Although your OP focused on deuterium and tritium, mining seawater for minerals has been practiced for centuries:
    https://en.wikipedia.org/wiki/Sea_salt
     
  12. Sep 23, 2017 #11
    I do agree; but, with a caveat. Mainly, that the markets invisible hand will make the extraction process of various elements and isotopes of hydrogen a reality via progress in technology and optimization even without incentives from the government or governments to support and facilitate the adoption of said technology. I also don't believe in completely free markets due to negative externalities (climate change) and the tragedy of the commons type situations. So, I'm basically arguing here is that we ought to invest in mining rare eath's and hydrogen isotopes all with one stone by extracting it from seawater. I doubt, any single company would do this, so yeah I'm making an appeal to governments to go after extracting elements from seawater.

    Currently, from what I read, is that extraction of uranium from seawater is approaching the cost of mining it. Mind you, there are other valuable elements in seawater that are worth extracting apart from uranium, despite considerable investment in finding ways to extract uranium from seawater due to national interest and reliance on uranium by other countries to provide cheap energy (Japan and the US despite the heavy regulations imposed on nuclear).

    Anyway, I think that we don't need to destroy the Amazon rainforest, or do other things that cause the destruction of the environment for elements if it can be extracted cheaply and economically from seawater. So, there's my political and what biased me would say 'the rational thing to do'.
     
  13. Sep 23, 2017 #12

    russ_watters

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    It would depend on the element, but basically if you can just dig it out of the ground it is a lot cheaper than trying to extract it from a few parts per million of seawater.
    Nobody is seriously contemplating that. That's just media hype.
     
  14. Sep 23, 2017 #13

    Drakkith

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    We currently have no need to do so, as alternatives are much cheaper and easier with the exception of mining a handful of elements/isotopes (which aren't heavily used in industry). There is no large-scale need for dueterium or tritium (which isn't even abundant in seawater), and almost all rare-earth elements are far easier to extract from the ground than they are from seawater. It would take drastic improvements in our current seawater extraction methods to begin to approach the lower cost of mining these elements from the ground.

    You're assuming that with some unknown amount of investment, the extraction process will be more economical than current methods. But you don't know that. We could invest billions and never approach the lower cost of current methods. You're also assuming that these new methods will be better for the environment. But again there's no way to know what the impact of undeveloped methods will be. If a cheap and highly efficient process also dumps thousands of tons of a harmful byproduct back into the sea, that may not be the better method.
     
  15. Sep 23, 2017 #14
    Yeah, but the flipside is that if we invest in the technology and there aren't any hard limits on the issue then we could have a sort of shale moment in regards to rare earth elements or deuterium and tritium. It sounds like a stretch; but, maybe someday given the right circumstances (high enough prices) it could become possible.

    With the current investments in uranium extraction, we're at a stage where it's only 2-3 times more expensive to extract uranium from seawater than mine it. You also save a lot of overhead costs by having the extraction, processing, and other costs accounted for in one place. Also, uranium isn't that an expensive an element to mine.

    In the case of deuterium and tritium, which I think is only produced via nuclear reactors and breeder reactors, then you have no other choice to minimize costs than to extract it from seawater. All that's needed is demand (not used in weapons but in fusion reactors)

    I might be wrong.
     
  16. Sep 24, 2017 #15

    Drakkith

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    Fusion power is, at best, decades away from reaching large-scale commercial application. Assuming ITER produces positive net energy, there's still a number of important issues that need to be solved, which takes time. There's simply no incentive to invest in improving a technique that has no demand in the near future.
     
  17. Sep 24, 2017 #16
    I agree; but, hopefully, you are wrong about how long till fusion will become a viable source of energy.
     
  18. Sep 24, 2017 #17
    If the discussion on this needs to go further, a new thread would be appropriate.
    Your statement implies that companies such as Deep Space Industries, Planetary Resources and others are not serious. That in turn would suggest that their investors are fools or the companies constitute some form of scam.

    Back on topic, this article (Extracting Minerals from Seawater: An Energy Analysis) considers the energy budget for mineral extraction. This is the abstract:

    The concept of recovering minerals from seawater has been proposed as a way of counteracting the gradual depletion of conventional mineral ores. Seawater contains large amounts of dissolved ions and the four most concentrated metal ones (Na, Mg, Ca, K) are being commercially extracted today. However, all the other metal ions exist at much lower concentrations. This paper reports an estimate of the feasibility of the extraction of these metal ions on the basis of the energy needed. In most cases, the result is that extraction in amounts comparable to the present production from land mines would be impossible because of the very large amount of energy needed. This conclusion holds also for uranium as fuel for the present generation of nuclear fission plants. Nevertheless, in a few cases, mainly lithium, extraction from seawater could provide amounts of metals sufficient for closing the cycle of metal use in the economy, provided that an increased level of recycling can be attained.
     
  19. Sep 24, 2017 #18

    russ_watters

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    Yes.
     
  20. Sep 25, 2017 #19
    It is my understanding that we "mine" salt and potable water from seawater right now.
     
  21. Sep 25, 2017 #20
    Source.
     
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