Folks, I think biochar suffers from the same fate as most biomass options.
Because of the low efficiency with which ecosystems convert sunlight to reduced carbon and because only a fraction of this reduced carbon will be converted to biochar, biochar options are unlikely to be able to offset more than 1 W of fossil-fuel CO2 emissions per square meter of land area. My post-doc has done some calculations indicating that this estimate might be a factor of 5 too small (taking into account other inputs and inefficiencies). We in the United States each use about 10 kW of energy, so this would be on the order of a hectare per person at the higher efficiency, 5 hectares at the lower efficiency. For 7 billion people at 2 kW, this is 1.4 x 10^13 m2, or roughly 10% of land area on Earth at the higher efficiency -- roughly the amount of land already devoted to agriculture -- or half the land area on Earth if my post-doc is right about the lower efficiency. So, this is another one of those things that could be good to do where appropriate, but is not likely to be a major player in the grand scheme of things. Best, Ken ___________________________________________________ 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 Tue, Apr 14, 2009 at 6:24 PM, dsw_s <[email protected]> wrote: > > I don't get the impression that the anti-biochar pdf is very > credible. For example, it suggests that there's basically no degraded > land in the world, that could be improved with biochar. It's a big > world. There's a lot of not-so-degraded land, and a lot of degraded > land. It wouldn't surprise me if the loudest claims over the last > couple decades were grossly exaggerated as to how much biological > productivity was being lost as vast areas of the Amazon got clear-cut, > eroded, and turned into quasi-desert. But to dismiss biochar out of > hand for lack of land to improve with it (even if it works, which they > reject, and even if it's affordable, which they reject, and so on) > just sounds as though they're looking for anything that would > invalidate biochar and then reasoning backward to the putative facts. > It may be that the improvable acreage is enough only for X gigatons of > carbon to have any benefit, with X too small to be a big part of the > overall picture. It would still be able to generate legitimate carbon > credits up to that point. > > On Apr 14, 9:58 am, Ray Taylor <[email protected]> wrote: > > I thought we should rename this biochar for the sake of the archive. > > > > Does biochar hold water significantly better than the organic matter > > it was made from? Especially if the latter was used as mulch? > > > > [See YouTube "Greening the Desert" - clip from permaculture > > institute of Australia] > > > > Thank you all for bringing biochar to my attention. I like the > > fact that (for Africa) it can be locally produced in low-tech kilns. > > > > I'd be interested to know if there is a site which replies to the > > following limitations/drawbacks: > > > > http://www.biofuelwatch.org.uk/docs/biocharbriefing.pdf > > > > Raywww.globalcoolers.net > > > > On Apr 14, 3:20 am, David Schnare <[email protected]> wrote: > > > > > My Center is doing a major report on putting carbon back into the soil > as > > > the means to developing two kinds of market mechanisms for farmers, > > > nutrients and carbon. I'll keep the group informed as we prepare our > > > materials, but just to give you a heads up, this is no silver bullet > (for > > > carbon). Biochar is better than crop detritus (no till farming), but > both > > > lose carbon due to microbial action (CO2 emissions). However, both do > a > > > terrific job creating a substrate for water. They take high clay soils > and > > > turn them into an organic sponge, holding nutrients in the ground, > attached > > > to the invested carbon. > > > > > David Schnare. > > > > > On Mon, Apr 13, 2009 at 10:03 PM, dsw_s <[email protected]> wrote: > > > > > > Wow, that sounds very promising, although we'll have to see about the > > > > economics. > > > > > > I hadn't heard (or hadn't absorbed) that the biochar was to come from > > > > a pyrolysis process that makes oil and gas, so there's more > > > > hydrocarbon and less just-plain-carbon than there would be in > charcoal > > > > from burning in open air. I don't know how stable regular charcoal > is > > > > either, although it sounds as though it's much more stable than I had > > > > thought. I would certainly expect biochar or ordinary charcoal to > > > > improve water retention (at least in most soils), and one of the > > > > references in the Wikipedia biochar article says it does (without > > > > saying for what kinds of soil, as far as I saw). > > > > > > I hope we study soil ecology before doing it on a very large scale, > > > > though. > > > > > > On Apr 12, 5:18 am, Andrew Lockley <[email protected]> wrote: > > > > > Biochar is highly stable in soils, and lasts centuries-millennia as > Terra > > > > > Preta. > > > > > http://en.wikipedia.org/wiki/Biocharhttp://en.wikipedia.org/wiki/Terr... > > > > > I understand it also bulks up the soil, trapping '3rd party' > carbon. > > > > > > > I am unsure whether this either affects the hydrological properties > of > > > > the > > > > > soil, or promotes forest regrowth. If either were the case, it > could > > > > have > > > > > the cloud-inducing effects discussed. This effect could be highly > > > > > significant and I hope someone expert can consider it. > > > > > > > A > > > > > > > 2009/4/12 dsw_s <[email protected]> > > > > > > > > But wouldn't the carbon in the biochar get returned to the > atmosphere > > > > > > fairly quickly if it were used that way? > > > > > > > > On Apr 11, 6:24 pm, Andrew Lockley <[email protected]> > wrote: > > > > > > > It would be very interesting to see if biochar has a similar > effect. > > > > If > > > > > > > biochar could lock up carbon in soils, thicken soils, preserve > and > > > > spread > > > > > > > forests and brighten clouds it would have benefits that could > > > > reasonably > > > > > > be > > > > > > > described as 'ginormous'. > > > > > > > I'd be interested to know if anyone in this group could explore > these > > > > > > > effects and potentially look at doing a paper or a model run on > them. > > > > > > > > > A > > > > > > > > > 2009/4/10 dsw_s <[email protected]> > > > > > > > > > > That sounds a lot like how I imagine geoengineering can work. > A > > > > > > > > suggestion I've made is that materials like expanded > vermiculite > > > > and > > > > > > > > perlite (basically rock popcorn) could be used to increase > water > > > > > > > > retention in soil for both agricultural and climatic benefit. > The > > > > > > > > climate benefit includes CO2 removal by weathering, but the > > > > > > > > distribution could also be chosen to optimize cloud patterns. > > > > > > > > > > On Apr 9, 11:50 am, Ray Taylor <[email protected]> wrote: > > > > > > > > > Hello all, > > > > > > > > > > > I've been in consultation with a range of land-atmosphere > > > > > > > > > and cloud meteorologists, looking at scope for increasing > > > > > > > > > stratus and cumulo-nimbus over land in regions identified > > > > > > > > > in GLACE (nasa). > > > > > > > > > > > Literature review available atwww.globalcoolers.net > > > > > > > > > > > Focus is on West Africa and rainwater harvesting, > > > > > > > > > pilot studies plus 4 continents alliance-building. > > > > > > > > > > > Anyone interested in collaborating? > > > > > > > > > > > Ray Taylor > > > > > > > > > > > ray [at] andy-taylor.org > > > > > -- > > > David W. 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