[Gasification] Re: RE: [ethos] RE: [Stoves] Charcoal Stoves (Thomas Reed)

[John Hofmeyr]

Hi Tom and others,
In Message-ID: <44948947.5070903 at comcast.net> Tom Reed wrote: 'The question of "combustability" and efficiency is very complex.  Conventional charcoal made for cooking represents a "buffered endpoint" in charcoal making.' 

Questions were raised about the CV and volatiles content of charcoal with respect to its efficiency in cooking. I wonder whether the fixed carbon content is maybe a more important consideration, because this is the value which will translate into the utilisable energy, especially for grilling, simmering and stewing. 
I introduce this idea, because, while the energy in the volatiles is important for ignition, I think this energy is likely to be burnt off rapidly? 
Therefore, would this energy only be useful, for example, to bring a pot to the boil? 
If yes, would the energy from the glowing charcoal be recoverable more efficiently and over a longer period?
And would this energy be maximised if the Fixed Carbon content of the charcoal is maximised, but with balanced volatiles for ignition (about 12-15%%, dry basis)?

I think it is for this reason that the EU specifications for charcoal tend to require a fixed carbon content above 80%, to ensure smokeless burning and to avoid rapid burn-off  of volatiles.

Further, on  Sent: Monday, June 05, 2006 3:35 PM Dean wrote: "2/3rds of the energy in wood is lost when making it into charcoal."

Properly-carbonised wood returns ~70% of its CV as solid, in the form of biocharcoal with Fixed Carbon >80%.
By this I mean for example:
12000 tpa wood at 25% moisture equivalent to 9000 tpa bone dry at 19GJ/ton, yields 4000 tpa biocharcoal (80%FC) at 30GJ/ton. 

Regards,    John in Joburg