[SustainableTompkins] Biochar (Terra Preta)

[Marian Brown]

Sorry - inadvertently hit a key that sent this before I was finished. I 
don't believe you will be able to follow the link shown, as I accessed 
this thru our internal Library server... and I don't know if Discover 
on-line will allow you to access the full text version of this 
publication. I believe it was in the April Discover issue (at least the 
article on-line is dated 4/30/2007). It's a fascinating piece that 
offers a little more depth about terra preta. Marian

Marian Brown wrote:

> 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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>