[Stoves] Calculating cooking costs and char costs ----Re: [biochar] Where to discuss STOVES AND CARBON offsets and drawdown

[Crispin Pemberton-Pigott]

Dear Paul

The highest practical (actual) yield I have heard of is the rapid charcoaling technique using high pressure (5 bars) in Hawaii (patented).

They had a yield of 45% by mass, but not as a % of carbon. It sounds like someone is making up or misunderstanding something about charcoal yield. That is 45% of the original dry mass, which if course contains a lot of volatiles still. The carbon content is unlikely to reach 85% because of the high volatile fraction. We could ask, of course.

Biomass is 48-52% carbon my mass and there is no way anyone is going to get even torrefied wood out with almost all the carbon remaining. The reason is that there are hydrocarbons that evaporate below 280 C and it is not possible to retain nearly 100% of the carbon.

I confess to not being impressed by the paper for the reason that it contains a lot of nods to various other papers in which an estimate, or an estimate based on other estimates, have been transformed into ‘facts’.

Ryan (2011) assuming that the dry mass can be converted to 47% carbon is not a fact, it is a bad assumption reflecting a misunderstanding (at least) about what is in biomass and what is in charcoal. Treating it as a fact is unhelpful.

Regards
Crispin


char costs ----Re: [biochar] Where to discuss STOVES AND CARBON offsets and drawdown

tom,

This quote is from Pam Jagger's article, and cites Ryan.

We assume that dry mass can be converted to carbon mass using 47%C (Ryan et al., 2011),
What does   "  47%C " actually mean?   That is not the same as   "% yield of charcoal compared to dry-weight of biomass"

Who can explain such a process with such a high yield of charcoal?    I did not think that it is possible, unless it is a bit beyond torrified wood.

Paul

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