You get energy *out* by partially burning biomass in a way that sequesters CO2 *and* improves the soil for hundreds of years. What's not to like?
Jon ================================================================== http://energybulletin.net/29673.html A handful of carbon Johannes Lehmann, Nature ...An existing approach to removing carbon from the atmosphere is to grow plants that sequester carbon dioxide in their biomass or in soil organic matter2. Indeed, methods for sequestering carbon dioxide through afforestation have already been accepted as tradable 'carbon offsets' under the Kyoto Protocol. But this sequestration can be taken a step further by heating the plant biomass without oxygen (a process known as low-temperature pyrolysis). Pyrolysis converts trees, grasses or crop residues into biochar, with twofold higher carbon content than ordinary biomass. Moreover, biochar locks up rapidly decomposing carbon in plant biomass in a much more durable form4. The precise duration of biochar's storage time is under debate, with opinions ranging from millennial (as some dating of naturally occurring biochar suggests) to centennial timescales (as indicated by some field and laboratory trials)5. Whether biochar remains in soils for hundreds or thousands of years, it would be considered a long-term sink for the purposes of reducing carbon dioxide emissions. ...Biochar is a lower-risk strategy than other sequestration options, in which stored carbon can be released, say, by forest fires, by converting no-tillage back to conventional tillage, or by leaks from geological carbon storage. Once biochar is incorporated into soil, it is difficult to imagine any incident or change in practice that would cause a sudden loss of stored carbon. The bottom line is that plant biomass decomposes in a relatively short period of time, whereas biochar is orders of magnitudes more stable. ...At the local or field scale, biochar can usefully enhance existing sequestration approaches. It can be mixed with manures or fertilizers and included in no-tillage methods, without the need for additional equipment. Biochar has been shown to improve the structure and fertility of soils, thereby improving biomass production3. Biochar not only enhances the retention6 and therefore efficiency of fertilizers but may, by the same mechanism, also decrease fertilizer run-off. For biochar sequestration to work on a much larger scale, an important factor is combining low-temperature pyrolysis with simultaneous capture of the exhaust gases and converting them to energy as heat, electricity, biofuel or hydrogen ...The consequences of climate change are already being felt1 and there is an urgency not only to identify but also to implement solutions. Biochar sequestration does not require a fundamental scientific advance and the underlying production technology is robust and simple, making it appropriate for many regions of the world. It does, however, require studies to optimize biochar properties and to evaluate the economic costs and benefits of large-scale deployment. (9 May 2007) The full article is behind a paywall. A good place to start looking for more information is Professor Lehmann's homepage. Contributor SP writes: For the Terra Preta fans out there. _______________________________________________ RSS, archives, subscription & listserv information for: [email protected] http://lists.mutualaid.org/mailman/listinfo/sustainabletompkins free hosting by http://www.mutualaid.org
