How many watts per square meter of solar energy can be used to reduce carbon that can be stored as biochar? How many watts per square meter is needed to process this organic matter?
Do you really think it reasonable to think that 10% of global primary productivity of land plants can be stored as biochar? Note that Haberl et al (2007) estimate that total global total food harvest is about 1.7 GtC / yr and global wood extraction is about 1 GtC / yr, so the 9.5 PgC / yr number cited by Lehmann et al (2006) represents carbon flows that are more than 5 times bigger than all the food harvesting in the world and more than 9 times bigger than all wood extraction in the world. These kinds of flows may be physically possible, but I remain skeptical regarding the practical feasibility of producing biochar at this scales. Haberl, H., K.-H. Erb, F. Krausmann, V. Gaube, A. Bondeau, C. Plutzar, S. Gingrich, W. Lucht, M. Fischer-Kowalski, 2007. Quantifying and mapping the human appropriation of net primary production in earth’s terrestrial ecosystems. Proceedings of the National Academy of Sciences of the USA 104, 12942-12947. ___________________________________________________ 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 Sat, Sep 26, 2009 at 8:32 PM, Manu Sharma <[email protected]> wrote: > Thank you, Peter. Your arguments are well made. > > Have you considered making a formal submission to the Royal Society for a > review of their position on this issue? > > Manu > > > On Sat, Sep 26, 2009 at 5:50 PM, Peter Read <[email protected]> wrote: > >> >> Ken, Simon >> >> As it was I that said it, I had best front up. >> >> My objection on first reading was to the passage immediately following >> Simon's quote, which is a gratuitous shift from policy relevance to policy >> prescription, viz: >> "Biochar and other forms of sequestered biomass have not yet been >> adequately >> researched and characterised, and so should not be eligible for carbon >> credits under the UNFCCC flexible mechanisms until there is a reliable >> system in place for verifying how much carbon is stored, and the wider >> social and environmental effects have been determined. Substantial >> research >> will be required to achieve these conditions for methods other than BECS". >> >> However, as regards the words that Simon quotes, one concern is a matter >> of >> emphasis, interpretation and tone. For instance, there are in aggregate >> about 15Gt p.a. crop and forestry residues and animal dung, which may be >> expected to rise to 20Gtp.a. (with ~10Gtp.a. C content) with population >> increase to 9billions. If the lot were pyrolyzed with 50 per cent C >> capture, and the product used for soil improvement, that would yield the >> lower end of the Lehman et al quoted range without any growth at all "in >> the >> resources devoted to producing" [[not "biofuels" but biochar is presumably >> intended]]. There would not be conflict with the use of agricultural land >> but synergy, with improved soil leading to increased crop yield. >> >> In a single sentence the RS writer manages to state that "using crops >> [PRESUMABLY HE/SHE MEANS CROP RESIDUES] for renewable fuels would be in >> conflict with using agricultural land for the production of food AND/OR >> BIOFUELS" !! Beyond the circular non-sequitur, the sentence is about >> biofuels and not about biochar at all. >> >> Next, a negativistic sentence "However, unless the sustainable >> sequestration >> rate exceeds around 1 GtC/yr, it is unlikely that it could make a large >> contribution." contains a false premise [as per the numbers above] which >> is >> then carried through to a prominent conclusion of low effectiveness in >> table >> 2.4 >> >> As regards final sentence that Simon quotes "might increase the cost and >> reduce the availability of food crops" is precisely the opposite of what >> would happen with conversion of currently largely wasted or inefficiently >> used farm and forestry residues to soil productivity enhancing biochar. >> >> As Ron Larson has noted, there is an extraordinary failure to quote the >> enormous positive literature on biochar, conveniently referenced and >> summarized in book format published in London IN MARCH 2009, within 2 >> miles >> of the RS Carlton House Terrace headquarters [Biochar for Environmental >> Management, Eds J Lehmann and S Joseph, Earthscan] which contrasts >> strangely >> with the Report's favourable attitude to BECS where the literature is >> sparse >> (possibly a convenience) and where success is entirely dependant on the >> infant CCS technology. There is not the slightest doubt that we know how >> to >> pyrolyze. >> >> As regards the gratuitous policy prescriptive paragraph, the establishment >> of a reliable system for verifying how much C is stored through commercial >> biochar application to soil is no different from estimating fossil fuel >> emissions - quantities and quality assay will.become available through >> normal accountancy procedures and can be aggregated in the same way as is >> done for coal, except the movement is down into the gropund rather than up >> out of it. As biochar is "finely divided pyrolyzed biomass prepared >> [expensively] for soil improvement" purchasers are not going to waste if >> for >> fuel (especially as preparation will likely involve wetting and doping >> with >> nutrients and/or fungal spores etc., somewhat spoiling combustion >> properties). Nobody is talking about carbon credits for increased labile >> soil C resulting from increased productivity or about unregulated backyard >> operations, though much valuable experimentation is going on in that way. >> As regards the RS concern over "the wider social and environmental >> effects >> " it would be good to see the same applied to already large scale >> bioenergy before getting too excited about the (likely beneficial) social >> and environmental effects of infant biochar. >> >> While I do not generally favour ad hominem arguments it may be noted that >> there is not a single member of the working group and review panel that >> has >> a publishing record in the field of biochar. >> >> Hope that helps >> Peter >> >> --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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