Our latest offering on abiotic CDR can be found here: http://www.pnas.org/content/early/2013/05/30/1222358110.full.pdf
Some highlights: air CO2 captured and safely stored - check carbon-negative H2 produced - check ocean alkalinity beneficially increased, OA and impacts reduced - check <$100/tonne CO2 mitigated, about the cost of CCS - check OK, more research is needed to better evaluate all of this. While trying to locate the funds to do this, perhaps the APS would like to reconvene its crack, air capture evaluation team and have a go. In any case, constructive comments and criticism invited. Another point we make is that reducing air CO2 need not involve air capture. By adding hydroxide to regions of the ocean that naturally degas to the atmosphere (e.g. upwelling systems), excess ocean CO2 is consumed and the natural ocean CO2 flux to the atmosphere (>300 GT/yr) is reduced along with the air CO2 burden, sidestepping the need for more difficult air capture. Air scrubbing is not necessary; cost effective and safe ways of producing and applying (geo)chemical base to CO2-degassing regions of the ocean would seem an easier alternative, especially considering that effective air capture ultimately also requires effective ocean CO2 removal (Cao and Caldeira). Bio approaches that could reduce CO2 flux to air include OIF, biochar, and CROPS, but while likely cheaper, these don't also generate ocean alkalinity and supergreen H2. Other ideas? Greg -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
