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

[Richard Stanley]

Your points taken Crispin, 

On the 50% values Insitu --of course: You have a solid point. No lo contestare ! In the form of a hollow core briquette its another story. The heat values we are getting run more in the low 20mjs. The reason has to do with  infra red reflectance within the core durign the burn. Look at the burn again in the  holey briquette rocket stove of rok Oblak It is very  near to a gassifier flame. 
On charcoal drying up…that would be worse than beer produciton halting out here. (have seen the latter in the 70's with near riots nationwide..) Thats why Paal and Otto Formo's solution of burning biomass and making char out of it is such a good idea.

Whomever pays for paper or charcoal dust, will almost assuredly kill their briquette business (at least the wet process hand production, microenterprise-based type): It's all very contingent upon getting / adapting blending FREE resources.  
I am yet to be convinced that much more than 20% (by dry weight) of waste  charcoal is needed in a biomass briquette, though. 

One can be otherwise pyrolising, charring and gassifying a biomass briquette all in one go-- during its actual point of application, especially if the mentioned pre drying pre heating technique is followed.  Nor is paper necessary where you have chopped and well retted field grasses and straws to do the work of binding..

Based on reports from the producers and trainer teams whom we know of here in Tanzania, the direct consequence of briquette production is replacing demand for  about 2000 tons of wood fuel this year--in the going local combination of wood or charcoal. last year it was 298 tons. 
We started training producers in 2007 and from them, trainers in 2009.   

Kind regards,
 Richard Stanley
Dar



On Dec 1, 2011, at 10:05 PM, Crispin Pemberton-Pigott wrote:

> 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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