*It’s hard to see how the energy cost of the ocean alkalinity scheme can get much below the cost of CaCO3 calcination .
*What about using power plant flue gases to dissolve carbonates? That seems to be an ocean alkalinity scheme that has energy costs well below calcination. ___________________________________________________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA [email protected] http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab +1 650 704 7212; fax: +1 650 462 5968 On Fri, Dec 11, 2009 at 11:33 AM, David Keith <[email protected]> wrote: > Greg, > > > > To me it’s just the common definition; I did not intend to say anything > about relative merits. The topic was air capture and that seem enough for > one article. I think the geochemical approaches that involve adding > alkalinity to the oceans are worth serious work that’s why I wrote the > article geochemical carbon management article. I have also pushed this idea > onto agendas at various research planning meetings (e.g., the NAS advanced > sequestration meeting), and we have considered adapting calcination > technology we develop for air capture to the CaO or MgO scheme though we are > not putting serious work into it. > > > > In my view there is no way to make a simple choice between them. There are > significant technical and institutional and governance challenges with > adding alkalinity to the ocean. On the other hand, restoring PH could be a > direct local environmental benefit. > > > > It’s hard to see how the energy cost of the ocean alkalinity scheme can get > much below the cost of CaCO3 calcination and the electrochemical schemes are > expensive. One might argue, then, that air capture has lower theoretical > energy cost (10’s of kJ/mol vs 100’s) but no one knows how to make the low > energy AC work at low cost. > > > > Bottom line: real development work is needed on both; they should be linked > where appropriate; and finally, it’s far too early to pick winners. > > > > I know about the APS work, but I will reserve comments until it’s out. The > real test will be in a few years when serious end-to-end engineering cost > estimates are made public. > > > > Yours, > > D > > > > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<geoengineering%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
