Re: GAS-L: The Mystery of heat variance in biomass

[Peter Verhaart <pverhaart@optusnet.com.au>]

Stove dried wood contains about 50% carbon (at least I think that was the 
rule of thumb we adopted). Next we assumed the rest was H and O in the 
proportion of water. This gives C3 H4O2.
Nobody suggests this is accurate but works in the world of stovers.
There was a staff member at Eindhoven (not in our faculty, I am happy to 
say), who explained the charcoal making process as driving off the water.
If things were only that simple.

Piet


At 07:16 3/01/02 -0500, you wrote:
>Dear All:
>
>Actually, not much mystery here.
>
>If you examine the heating value of "fresh" biomass it can vary from 5 to 22
>MJ/kg due to variations in WATER CONTENT, ASH CONTENT, and possibly
>composition.  If however you look at the 100 or so samples on our website,
>www.woodgas.com , www.Phyllis.ne or others, you will see that the heating
>values vary from 18 to 22 MJ/kg based on BONE DRY, ASH free analysis.
>
>I use the average composition
>
>C H(1.4) O (0.six) to   represent ALL biomass, knowing that it all varies a
>little.  THere is also a formula at the site that predicts heating value from
>the ultimate analysis within about 1.5%.
>
>So, no great mystery if properly approached....
>
>Yours truly,                    TOM REED           BEF STOVEWORKS


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