[Stoves] Fuel classification system

[Tom Miles]

Frank,

Wood is still the reference fuel because it is the most prevalent even
though there will be lots of other residues mixed in or there will be areas
with mostly dung. You can't find the data if you don't know the species. 

Density is the single most important property of wood that differentiates
its burning characteristic. You can plot ignition time, the volume burning
rate, and percentage left as charcoal all as a function of wood density. CO,
PM and VOC emissions also appear to vary with density.  

Wood species usually split between hardwood and softwood but not always.
We're looking for densities relative to the current reference fuel which is
douglas fir at about 530 kg/m3. Bamboo is 350 kg/m3. Willow is 430 kg/m3.
Mexican pines are similar to Douglas Fir. Higher altitude pines (Bolivia)are
soft pines with somewhat lower density. Ash and Birch are about 670 kg/m3.
Red oak is about 750 kg/m3. Bolivian commercial hardwoods are 600-1200
kg/m3. In each area there may be a dozen or more species used for fuel but a
few will probably account for the majority of use.   

The next distinction is between wood and non-wood. Grasses and agricultural
residues including corn cobs and husks have completely different properties
than wood.   

If we can identify wood species and characteritics relative to test fuels we
will have accomplished a lot. Next can look at non-wood fuels.        

Tom

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of frank
Sent: Thursday, January 04, 2007 10:00 AM
To: Discussion of biomass cooking stoves
Subject: [Stoves] Fuel classification system

Tom and stovers,

Tom Miles wrote:

>Crispin,
>
>Properties of Species used for cookstoves
>
>It would be useful to identify the species that are used in stoves. We 
>can start with the douglas fir softwood that has been used by Aprovecho 
>and in the residential testing. Red oak is the hardwood that is the 
>main reference fuel for heating stoves in the US. Canmet's emissions 
>testing used douglas fir and red oak. We can comparese the properties 
>of these hardwoods and softwood to the many species used in other parts 
>of the world using available information for density, typical moisture, 
>ash and heating value, chemical composition and burning behavior. The 
>hardwood vs softwood classification covers the main physical differences.
>
>I have seen some good area surveys in West africa that identify 
>principal species used for fuel and charcoal. I have not seen similar 
>information for Central america, Asia or other locations.
>
>Tom      
>
>  
>
I think the approach should be to not classify based on the species but set
up a classification system where the species of wood can fit into the
system. The problem with a system based on species is that there are many
types of fuel (like what Jeff is doing) that does not apply. Also there are
differences between old trees vs young and the same tree species from wet
area to slow growing dry areas. Then we mix wood when building a fire.
etc.etc.

Frank



-- 
Frank Shields
Soil Control Lab
42 Hangar way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com




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