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View Diary: Sea Urchin offers path to Cheap Carbon Sequestration (118 comments)

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  •  Glad someone called attention to this problem (6+ / 0-)

    Where are the huge amount of calcium ions required going to come from ? Certainly not from the nickel, which seems to be suggested in the description, nor from the major natural source of calcium, which is already in the form of calcium carbonate or calcium sulfate.
    The nickel evidently serves as a cheap catalyst of the carbonic anhydrase reaction (which, incidentally, occurs more slowly without any catalyst):
        CO2 + H20  -->  HCO3–  +  H+
    The products are bicarbonate ion and hydrogen ion (acid).
    Bicarbonate ion will react with (naturally occurring) calcium carbonate:
        HCO3–  +  H+  +  CaCO3 -->  Ca(HCO3)2
    to give calcium bicarbonate, which is water soluble.
    The effect of the carbonic anhydrase reaction in the oceans, catalyzed or not, is the serious environmental concern of ocean acidification, which in turn leads to solubilization of the calcium carbonate exoskeletons of marine organisms such as corals and, yes, sea urchins.
    So, dumping vast amounts of dissolved CO2 into the oceans necessarily causes acidification, which is the real problem with this scheme. It is not at all apparent how it could result in the net sequestering of CO2 as calcium carbonate. If you suggest that it's going to come from lime, remember that lime is produced by heating CaCO3 to high temperatures to drive off the CO2 in the first place.

    •  Sea water already too acidic (2+ / 0-)
      Recommended by:
      Sandino, A Siegel

      As noted in this Seattle Times article, sea water is already so acidic that oyster larvae are dying due to their shells dissolving.

    •  How about the huge amounts ..... (2+ / 0-)
      Recommended by:
      noemie maxwell, Fantastic

      of naturally occurring calcium ions in "hard" ground water?  

      This is a very encouraging piece of news if as indicated a renewable, nickle catalyzed carbon sequestration technology were developed.

      Labor was the first price paid for all things. It was not by money, but by labour, that all wealth of the world was originally purchased. - Adam Smith

      by boatwright on Wed Feb 06, 2013 at 09:42:24 AM PST

      [ Parent ]

      •  First, it's trivial amounts (0+ / 0-)

        when compared to the amount of CO2 produced by combustion of 'mined" Carbon, and second, there's the energy required to separate what little Calcium there is to be had from that source.

        Oh, and there's nothing "renewable" about the process as described (except for catalyst recovery).  The process requires depletion of one reactant (Calcium) and non-recoverable energy to run it (which may or may not be "renewable" depending on the energy source).

        Fake Left, Drive Right . . . not my idea of a Democrat . . .

        by Deward Hastings on Thu Feb 07, 2013 at 07:00:47 AM PST

        [ Parent ]

    •  you said: (2+ / 0-)
      Recommended by:
      BoxNDox, IreGyre
      So, dumping vast amounts of dissolved CO2 into the oceans necessarily causes acidification, which is the real problem with this scheme.
      I don't think the diary writer was trying to envision a process for CO2 to metal carbonate or bicarbonate that takes place in the ocean.  I think the idea being promoted was to recreate that natural process in an industrial process equipment approach to try to achieve the same effect.

      Whether such an industrial technology approach is either technically or economically feasible or practical....depends on the reaction rate that is promoted by the catalyst.

      •  Good point, but it's still very difficult (3+ / 0-)
        Recommended by:
        MGross, Nowhere Man, Deward Hastings

        to imagine any inexpensive source of ionic calcium on a scale comparable to the CO2 generated in the fossil energy industries. For just one mind-boggling example, see here.

      •  The problem from another angle (2+ / 0-)
        Recommended by:
        LakeSuperior, Deward Hastings

        Whatever the source of ionic calcium, the overall reaction to form calcium carbonate is:
            Ca2+  +  CO2  +  H2O  -->  CaCO3  + 2 H+
        which means there are 2 equivalents of acid to be disposed of somehow for every CO2 trapped. Where does that acid go? Into the ocean or rivers, like most of our wastes? Bad idea. So, as I said, I don't see how the "carbonic anhydrase" process, however achieved, gets us anywhere.
        The one large scale process for sequestering CO2 that doesn't have the proton problem is the following:
            6CO2  +  6H2O  -- (light) --> C6H12O6
        aka photosynthesis. As some commenters in the thread below point out, that's the way we should be going.  

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