Hansen writes about biochar in his recent Target paper:
"Carbon sequestration in soil also has significant potential. Biochar, produced in pyrolysis of residues from crops, forestry, and animal wastes, can be used to restore soil fertility while storing carbon for centuries to millennia [84]. Biochar helps soil retain nutrients and fertilizers, reducing emissions of GHGs such as N2O [85]. Replacing slash-and-burn agriculture with slash-and-char and use of agricultural and forestry wastes for biochar production could provide a CO2 drawdown of ~8 ppm or more in half a century [85]." Both references (84 and 85) are from Lehmann, who appears to be the central figure promoting biochar solutions. By combining biochar production with energy production from biomass through pyrolysis, the potential in both prevented fossil fuel emissions and carbon fixation is much greater. Pyrolysis produces 3–9 times more energy than is invested in generating the energy [Lehmann et al., 2006]. Combined with the positive side effects on soil fertility a.o. it seems a promising strategy, though its global potential in terms of CO2 sequestration is probably limited by the land available for biomass production. The net environmental effects will also be strongly determined by how the biomass was grown. The only negative (or better, critical) note that I've come across re biochar is that we don't know enough about its effects on soils: “Much remains unknown about how charcoal influences the dynamics of native soil organic carbon and its loss as CO2. As long as this remains the case, strong advocacy for the addition of charcoal or biochar to soil to offset human-induced CO2 emissions remains premature.” [Wardle et al, 2008]. Bart On Jan 23, 8:03 pm, Tom Adams <[email protected]> wrote: > On Jan 23, 10:28 am, Tom Adams <[email protected]> wrote: > > > > > > > On Dec 8 2008, 7:41 pm, "David B. Benson" <[email protected]> > > wrote: > > > > On Dec 6, 3:48 pm, "[email protected]" > > > > <[email protected]> wrote: > > > > ... > > > > Are there any known negatives > > > > about biochar? Any idea of the economics involved? > > > > Biochar is almost surely to include some VOCs (volatile organic carbon > > > compounds). More than just a little of this is quite bad. Some tests > > > suggest that soils with 30% biochar have overdone it and radishes > > > won't start. > > > > On a large scale, assuming no centralized source of dry biomass > > > collected for other reasons, the cost will be about $120--150 per > > > tonne once spreading costs are included. Very oten biowastes are > > > collected anyway during harvest, dropping the cost down to around $75 > > > per tonne after spreading. Modest amounts produce impressive returns > > > on investment for both maize and wheat (probably other crops as well). > > > > Here is a useful link for you: > > > >http://terrapreta.bioenergylists.org/ > > > Lovelock thinks its mankind's last hope: > > >http://www.newscientist.com/article/mg20126921.500-one-last-chance-to... > > > He was interview by Gaia Vince: > > >http://i161.photobucket.com/albums/t222/inkettes/SSAG%2022Feb2007/gai...Hide > >quoted text - > > > - Show quoted text - > > Five year's ago nuke plants were our last hope, according to > Lovelock. Now it's charcold. > > Lovelock may be the only person in history who lost a Nobel prize by > spouting off. He made the mistake of pooh poohing CFCs in the > atmosphere after he discovered them. Two other blokes (inspired my > Lovelock's discovery) got the prize, and there is room for 3 under the > rules. > > (Not to say that charcold production is a bad idea)- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. 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/globalchange -~----------~----~----~----~------~----~------~--~---
