[Stoves] HEDON Newsletter (30/11/2011)

[Crispin Pemberton-Pigott]

Dear Richard 

 

>Interesting argument but I feel that you leave out one very critical
element in your assessment: 

 

I agree I left out an analysis of biomass fuel processing. Thanks for
covering that base.

 

>Your assumption that the fuel ( as charcoal ) has to be transported is, I
assume, based on the fact that one cannot go around making charcoal in the
cities. 

 

That plus people usually make charcoal in fields and it has to be
transported to somewhere else to be used. I was really referring to the
trucking of urban fuel. It is apparently worth trucking charcoal 600 km in
Mozambique, and I believe the same for Dakar in Senegal as some of the wood
and charcoal is from Kaolack.

 

>The issue of transport does not figure into the equation for the biomass
briquette producer because of lower energy densities, although the
difference is hardly 50%, when comparing well made agro residue briquettes
to lump charcoal. 

 

I am very interested to know what you mean when you said hardly 50%. 50% of
what compared with what? If you have charcoal at 4-6% moisture and maybe 27
MJ/kg, what do you get from a leafy/grassy briquette and what from a
sawdust/mechanical paper (etc). I have heard from several people who write
to ask about drying the briquettes to move them more quickly. I figured the
stove with horns on the side for drying them is an elegant (good and simple)
solution: to apply waste heat coming through the stove body for drying. That
will elevate the energy per kg. But what is the actual heat yielded by an
average not-elegant stove. I was figuring on more like 15 MJ. That is where
I got the 50% of heat per unit mass.

 

The issue of transport does not figure into  the equation mainly because few
would tend to attempt widespread distribution to distant markets,  .

 

Agreed. Where I made an investigation into distribution from a large
producer (the super-max prison in Bloemfontein) it was still only as far as
the edge of town.

 

>Small is not only beautiful but logically linmited  by common sense. 

 

And always was.

 

Where a charcoal form of heat is preferred, the local producer will just
sweep up the waste crumbs and dust (15 to 20% generally) that accrues  just
from the handling of the charcoal (just from the truck to the  retailer(s)
and on to the customer.

 

 

Charcoal is of course here to stay though, but even if the cost of lump
charcoal goes up, the wastes tend to remain just that.  

 

This being up a point: what happens where there is little to no dust left
over anymore? That is a resource that is rapidly going to become
commoditized and enter the fuel supply chain. Isn't Chardust processing
about 7 tons a day? Pretty soon it will be like paper - you will have to pay
to get it.

 

Still, that adds value to the waste stream and someone gets a job out of it.

 

Regards

Crispin

 

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