Dear Friends
[Frank] The whole idea of torrefaction is confusing to me. Once wood loses weight after moisture it should be ‘torrefied’ up to weight becoming stabilized (~450c). where it is now biochar IMO. I’m just learning how to spell the words and trying to understand what they mean. That’s harder for me than developing a test to determine degree of torrefication. [Ron] [RWL3: Still confusing to me also - but more dialog is helping a lot (thanks). But I have to repeat that a temperature of 450 is ready to use as a soil amendment. I am OK with that if the gases have been productively used. But I am trying to wean urban cooks off of charcoal use - to be replaced by charcoal-making. My first economics are saying that the economics can be favorable - since the per kilo price of TBM should be appreciably less than the price of char (if not transported too far) - and its energy content is getting close. Charcoal using stoves are not that efficient - and there is no chance for an output as valuable as is Biochar.] [Crispin] In my experience, for a given level of technology, charcoal using stoves are invariably more efficient than all wood using stoves. I say that with reference to the stove and the energy available to go in it. If you are instead referring to the heat available at source and the quantity of delivered food taking into consideration the whole fuel supply and cooking system (a systems approach to the calculation) then the matter is still not settled at all. I have several times shown here with numbers that it is a toss-up, and that is before we get seriously into charcoal or TBM product development of which there is painfully little. Two things that readers should keep in mind is that the discussion of a certain fuel system cannot make informed comment on the potential for that fuel to be consumed efficiently, and the converse. I see the problem as one of allowing conclusions to be ad hoc applied to the other without a apply a consistent frame of reference. I particularly welcome a systems approach to the energy chain inclusive of transport and processing (energy) costs. Following that, there are social and environmental costs to be considered. These should not be ‘assumed for convenience’. Very little work has been done relating all three (in fact can anyone point to any?) A ‘triple bottom line’ analysis can be the talisman: Economic, social and environmental ‘costs and gains’. That is what social capital investments are all about (SoCap). Regards Crispin
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