Some years ago I calculated how much energy it would take to convert 100 ppm of CO2 into synthetic oil which could be stored in old oil fields safely for millions of years.
100 ppm of CO2 would be 470 cubic km of the stuff. It's what humans added to the atmosphere since ~1960. Had to define a new measure of energy, it would take about 300 TW years (check it if you want to quote it). I was doing this in the context of space based solar power. If you kept building power plants in space beyond replacing fossil fuels, to another 15 TW, it would take 20 years to put 100 ppm back in the ground. Much less energy if you take it out as CO2, but less of a blowout problem Keith Henson http://en.wikipedia.org/wiki/L5_Society On Tue, Nov 19, 2013 at 5:45 AM, Ning Zeng <[email protected]> wrote: > Or simply CRS (Carbon Removal and Storage). A few years back when this group > came up with the names SRM and CDR, I argued for CRS, reasoning that any CO2 > removal method has to be accompanied by storage as a truly workable carbon > sequestration strategy. many cheers, -Ning > > > On Monday, November 18, 2013 5:59:10 PM UTC-5, kcaldeira wrote: >> >> Folks, >> >> The question about whether biochar is a CDR technique and therefore >> "geoengineering" raises some interesting issues. >> >> Carbon Dioxide Removal (CDR) techniques involves to processes that are in >> principle separable: >> >> 1. Carbon dioxide removal from the atmosphere (or oceans) >> 2. Storage of that carbon in a long-lived pool. >> >> Carbon can be removed from the atmosphere using biological strategies >> (e.g., land plants, phytoplankton) or chemical strategies (e.g., direct air >> capture, accelerated chemical weathering). >> >> Carbon so removed must then be stored in a long-lived reservoir. Carbon >> can be stored in a reduced form (e.g., biochar, living forests) or in an >> oxidized form (e.g., CO2 injected in geologic reservoirs, Fe-fertilized >> biomass that has oxided into dissolved inorganic carbon in the deep ocean). >> >> Carbon stored in an oxidized form can be largely in the form of molecular >> CO2 (perhaps dissolved) or can be part of another compound such as CaCO3 >> (perhaps dissolved). >> >> What makes something CDR approach is a system property (i.e., air capture >> that vents back to the atmosphere is not a CDR approach; geologic CO2 >> storage without air capture is not a CDR approach; but put the two together >> and you have a CDR approach). >> >> On this taxonomy, I would consider biochar as a way of storing reduced >> carbon for long periods of time. Under this interpretation, biochar could be >> part of a CDR system, but as a process in-and-of-itself, biochar is an >> approach for carbon storage. Biochar does no carbon dioxide removal, so >> cannot itseld be a CDR technique. >> >> Therefore, it may make sense to talk about biochar as a carbon dioxide >> storage approach. As part of a system of biological carbon capture by land >> plants and storage using biochar, biochar can be part of a CDR system, but >> biochar itself is not a CDR system. >> >> Maybe we should be talking about CDRS (Carbon Dioxide Removal and Storage) >> instead of CDR. We should then specifiy both the Carbon Dioxide Removal >> (CDR) approach and the Storage (S) approach. >> >> Biochar is an S approach, not a CDR approach. >> >> Best, >> >> Ken >> >> _______________ >> Ken Caldeira >> >> Carnegie Institution for Science >> Dept of Global Ecology >> 260 Panama Street, Stanford, CA 94305 USA >> +1 650 704 7212 [email protected] >> http://dge.stanford.edu/labs/caldeiralab >> https://twitter.com/KenCaldeira >> > -- > 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 [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/groups/opt_out. -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/groups/opt_out.
