blimey. Can. Of. Worms. Well and truly opened. So - biochar. Great potential, should be (and is being) researched. But can it contribute one or more 'wedges'?
Since they say it well, and since Ron asked for quotes from the UK BRC submission: "Lehmann et al. (2006) estimate that current global potential production of biochar is 0.6 ± 0.1 Gt/yr. They estimate that by 2100 production of biochar could reach between 5.5 and 9.5 Gt/yr. There are very large uncertainties attached to these numbers, however, arising from competition for land-use, competition for use of biofuels and agricultural wastes and a huge divergence (of nearly 1000%) in different expert estimates of the potential future global supply of biomass for bioenergy purposes. Woolf (2008) estimates that if all existing agricultural crop residues were used to produce biochar, this would constitute 1 Gt of carbon storage. A reasonably conservative assumption would be that biochar has the potential to offset global atmospheric carbon emissions at the gigatonne per year scale by 2050 (and probably by 2030 if a concerted effort were made) – one of the climate ‘wedges’ in Pacala and Socolow’s (2004) schematic, hence comparable to other major mitigation activities (CCS, renewables, efficient vehicles, etc.)." Answer: proabably, but there is a lot of disagreement on the details. A few other points from the numerous responses: - Peter, in discussing the numbers you said of agricultural wastes "If the lot were pyrolyzed" which strikes me as a pretty big if. There is clearly <some> uncertainty on the figures. I don't think calculations starting from the total land area/global primary production/amount of food crops/grazing land available get us that far in nailing an accurate potential, although they are clearly a necessary starting point. You simply have to factor in things like transport costs/ logistics, competition for the material and so on. I'm looking forward to reading such a study for biochar. - policy prescriptiveness: I assume no-one round here objected to the RS's policy prescription for geoengineering research funding? Maybe the wording on biochar and CDM was strong, but let's not kid ourselves the RS shouldn't have been/wasn't allowed to/specifically ruled itself out of say whatever it wanted to in the report, including some comments on policy. - suspicion of carbon offsetting: Ron I think we were at cross purposes on that. I meant that many view the whole idea of carbon offsetting with suspicion, seeing it as a way for the west to offload the problem of cutting emissions onto others. Questions of additionality are a big issue too. Nothing to do with biochar specifically - and I don't necessarily agree with that take on offsets anyway. But that was the context for my emphasising the need to maintain the credibility of the CDM and obviously a good methodology will be key. - Opinion of Simon Shackley: Simon told me earlier he hasn't read the RS report yet. Meanwhile we don't know if he (or other UKBRC scientists) is or isn't in "significant disagreement" with it. In that context I shouldn't have speculated either - mea culpa. - Lenton and Vaughan figure for biochar potential: their table 2 has 400PgC cumulative up to year 3000 (not 2100) which is 0.4Pg/yr. In the text they discuss larger numbers per year but (I think) the total is limited by how much biochar they say can be stored on a given amount of land and factoring in the need to replenish decomposed biochar over such long time periods. Things we should be rushing into: energy efficiency, renewables, non- fossil powered transport, CCS (because without that we've no hope of a 2oC limit, so says DEFRA chief scientist Bob Watson anyway), etc etc. There are lots of things we absolutely should be rushing in to but I'm not convinced biochar is one of them. Proceeding at a good pace - sure. I just don't like the idea of rushing when it comes to food (agriculture). Opinions clearly vary on this! best wishes, simon On Sep 27, 12:20 pm, "Peter Read" <[email protected]> wrote: > Ken, Manu, > > I did not go into primary data but had in front of me one or two respectable > secondary sources that led to the "about 15Gt" number > > Strand and Benford , 2008 Env Sci and Tech, quote 4.98 Pg/yr for residues > from maize, wheat, soybeans, sugar cane, rice, sugar beet and barley. Jason > Clay in World Agriculture and the Environment (Island Press 2004) provides > additional data for Cassava, Potatoes, Sorghum, Bananas, Sweet Potatoes, > Plantain and Millet which I did not trouble to add in. Hall, et al in > Renewable Energy (Eds Johansson et al, Island Press 1993) turn it all into EJ > to get 35EJ for Maize, Wheat, Rice and Sugar Cane residues only, 41EJ for > animal dung, (excluding human dung which pyrolyzes fine) and 35 EJ for timber > residues. Roughly 3 x 4.98 led to 15Gt > > Haberl et al must have it wrong since the global food yield for Strand and > Benford's seven crops only (with an average harvest index of 0.44) is about 4 > Pg/yr or ~2PgC > > 9.5 Gt is actually about one sixth of global net primary productivity, not > one tenth, but one must be cautious of treating global NPP as a given, as > many ecologically focused writers seem to do. > > Nature (and much subsistence agriculture) optimises on resilience to secure > survival of the fittest and is not productively efficient. > > Read and Parshotam, 2007, cited in the RS report, provide Illustrative > calculations which show that, if managed efficiently, and with plausible > technological progress, only about 2.2GHa is needed (at a take up rate of > .088 GHa for 25 years) to shift 1120Gt from linked ocean and atmosphere (in > ratio ~45:55) by 2060, leading to pre-industrial levels around mid-century. > > I do not favour the vast monocultural developments that may seem to be > implied, but rather a wider dissemination of carbon conservative and > productively efficient management methods to land users worldwide. The > obstacle is not shortage of land but shortage of investment in land (and in > land users' human capital) -- investment on a scale comparable with current > investments in ever harder to get fossil fuels (i.e. tilling for bio-oil not > drilling for fossil oil). > > Peter. > > ----- Original Message ----- > From: Ken Caldeira > To: Manu Sharma > Cc: Peter Read ; [email protected] ; geoengineering > Sent: Sunday, September 27, 2009 8:18 PM > Subject: [geo] Re: Manifesto for Geoengineering > > 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 > > ------------------------------------------------------------------------------ > > No virus found in this incoming message. > Checked by AVG -www.avg.com > Version: 8.5.409 / Virus Database: 270.13.113/2396 - Release Date: 09/26/09 > 05:51:00 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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