One way of looking at the CO2 problem is that you are introducing a (weak) acid (CO2) into the environment.
(Recall that Arrhenius's famous 1896 paper was called "On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground". http://www.globalwarmingart.com/images/1/18/Arrhenius.pdf). The partitioning of CO2 between the ocean and the atmosphere is controlled by the oceanic acid-base balance. Rather than thinking in terms of sequestering CO2, we could think in terms of either sequestering an acid away from the system or adding a base (loosely, negative acidity) to the system. So, instead of injecting CO2 underground we could, say, add CO2 to the ocean and remove HCl from the ocean and inject the HCl underground -- this would have a similar effect on atmospheric CO2 content. Alternatively, you can add strong bases (i.e., alkalinity) to the ocean, which is chemically very similar to removing an acid. Any strong base will do, NaOH, Mg(OH)2, etc, etc. Finding a source of this alkalinity is a well recognized problem. House et al (2007) and Lackner et al (1995, 1997) have both proposed ways of getting this alkalinity from silicate rocks and Rau and Caldeira (1999) and Rau et al (2007) have proposed getting this alkalinity from carbonate rocks (however this would require oceanic disposal of the resulting CO2-enriched fluid). Kheshgi (1995) has also thought about ways to add alkalinity to the ocean. In contrast, Calera in their public documents show only seawater and CO2 as inputs to their process, with the implication that they will obtain their alkalinity from seawater. Best, Ken ----------------------- references *House, K.Z., House, C.H, Schrag, D.P., Aziz, M.J. Electrochemical acceleration of chemical weathering as an energetically feasible approach to mitigating anthropogenic climate change. Environ. Sci. Technol., 41(24): 8464-8470, 2007. Kheshgi, H. S., 1995. Sequestering atmospheric carbon dioxide by increasing ocean alkalinity. Energy, 20: 915-922. Lackner et al., 1995 K.S. Lackner, C.H. Wendt, D.P. Butt, E.L. Joyce and D.H. Sharp, Carbon dioxide disposal in carbonate minerals, Energy 20 (1995) (11), pp. 1153–1170. Lackner et al., 1997 K.S. Lackner, D.P. Butt and C.H. Wendt, Progress on binding CO2 in mineral substrates, Energy Conversion and Management 38 (1997), pp. S259–S264 Rau, G.H., and Caldeira, K. Enhanced carbonate dissolution: A means of sequestering waste CO2 as ocean bicarbonate. Energy Conversion and Management 40, 1803-1813, 1999. Rau, G.H., K.G. Knauss, W.H. Langer AND K. Caldeira. 2007. Reducing energy-related CO2 emissions using accelerated weathering of limestone. Energy, 32:1471-1477. * ___________________________________________________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA [email protected]; [email protected] http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab +1 650 704 7212; fax: +1 650 462 5968 On Fri, Apr 3, 2009 at 10:45 AM, concernedcitizen <[email protected]> wrote: > > Ken - Wanted to follow up on your statement re: needing strong bases. > What type of bases are needed and what strength. Is this just a scale > and cost issue or is there a fundamental roadblock here? Cheers: > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
