[SustainableTompkins] Biochar (Terra Preta)

[Marian Brown]

Jon - there was an interesting article about terra preta in Discover 
magazine earlier this year:

The article, called "Black Gold of the Amazon" by Michael Tennesen. I don't
http://ejournals.ebsco.com/RemoteSiteWithInstructions.asp?JournalID=112971&RemoteURL=http%3A%2F%2Fwww%2Ediscover%2Ecom%2Fissues%2F


Jon Bosak wrote:

>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.
>
>
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