[Terrapreta] torrefaction vs. carbonization

[Gerald Van Koeverden]

Nick,

I had to look up what torrefaction was:

"Torrefaction is mild pre-treatment of any biomass (including bamboo)  
at a temperature between
200 and 250° C. During torrefaction the properties of bamboo undergo  
changes, wherein the end
product has much better fuel quality compared to biomass for  
combustion application. The
decomposition reactions during this process results in bamboo  
becoming completely dry and
loose its tenacious structure, also the hygroscopic nature of the  
biomass is changed to
hydrophobic material. Besides this, the process increases the  
calorific value of the end product.
The actual weight loss in this period would be about 20 to 25 %  
whereas 90 % of the energy of
the parent dry material is preserved in the torrefied matter. The  
combustion process of this matter
has less problematic volatiles and hence the process is closer to  
that of charcoal. It can therefore
be used as an alternate to charcoal in many applications. It also  
makes the material immune to
attack by fungi. Hence long term storage without degradation is  
possible."

Based on 15 minutes of research, it doesn't look promising.  It would  
seem that this super-drying of wood makes it hydrophobic...and if it  
stays that dry in the soil, it would be difficult for nutrients to  
move through a soil solution into it.  Moreover, it doesn't sound  
like it is conducive for a 'fungal' bridge between itself as a  
microhabit for microrganisms with the soil;  in char mixed with  
composting material, the char actually becomes a microhabit for  
fungus...
However, this is only speculation.

How closely have you examined the torrefied wood you have found in  
the soil?  Does it 'house' microrganisms?  Has it absorbed soil  
nutrients?  Or is it merely an inert material taking up space?

gerrit



On 8-Dec-07, at 2:21 PM, Nikolaus Foidl wrote:

> Dear all!
>
> My charcoal costs at a charring efficiency of 42 % is around 35 US$  
> per ton
> Charcoal. Now after analyzing 15 year old soil where huge amounts  
> of forest
> where simply burned and charred. Now excavating I find huge amounts  
> of only
> torrefied wood pieces which as well did not degrade, like the charcoal
> chunks.
> Now looking at this and if torrefied wood would do the same as is  
> charcoal,
> why not save a huge amount of additional CO2 and just torrefy the  
> stuff and
> mill it and then burry it? Cost per ton would drop to half, CO2  
> taken out of
> the atmosphere rise by 50 to 70 %.
> Just an idea but maybe worth to be discussed.
> Best regards Nikolaus
>
>
>
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