[Stoves] More on the Alternatives to Charcoal.

[Paul Means]

Dale, Chrispen, Paul A, Ron, & All,

Dale, thank you for getting this discussion going.  I think we all  would
agree that the traditional charcoal production & use systems around the
world have much to be improved upon.

Some comments - many in response to Chrispen's comments:
1. I could not agree more about the social (& market) aspects of
substituting dried woody biomass for charcoal.  That is a big issue which
has yet to be tackled.  It could be a show stopper for some of the
alternatives.

2. In terms of transport economics, no doubt that charcoal has a
substantially higher net (LHV) energy density than dry wood, not to mention
wet wood.  Consequently for the same amount of energy shipping the same
distance charcoal wins hands down.
For my analysis I used 10% moisture which assumes either aggressive solar
drying or that some of the biomass is being burned to dry the remaining
fuel.  Even with this much drying, the hauling cost penalty of biomass over
charcoal is about 67%.  Where the analysis becomes interesting, at least to
me, is when the whole system is considered.  In this case we need to factor
in the efficiency of the charcoal production vs. the woody biomass
production and this effect on forest area required.   Bottom line is that
the charcoal must be hauled in from a much larger land area just because of
the gross inefficiency of the charcoal making process.  This has the
potential to make the hauling cost on a per MJ basis actually 40% LESS for
dried biomass.   I say potential because it will all be specific to the
forest area, it's density (tons of biomass / hectare) and it's distance
from the point of fuel use.  This collection hauling penalty for
traditional charcoal, has not been discussed much from what I have seen.
The other interesting point is that dried biomass is actually equivalent to
charcoal on a MJ / m3 basis.  Consequently, the truck will need to haul
more weight per MJ with dried biomass, but not more volume.

3. On the stove side,  there is much work to do, from what I can tell, to
make a TLUD burning dried biomass as attractive to the user as a charcoal
stove burning charcoal.  In fact it may never be.  However, it seems to me
that there is the potential.  Given that this fuel is consumed in the city
there should be an easy & efficient way to burn the residual charcoal.
 Also perhaps turn-down needs improvement in the gasification phase.   And
of course it needs to be simple to operate.  Each one of these issues may
represent substantial work to develop solutions for.

4. Speaking of development, a low capital method for distributed drying of
woody biomass is another area that will need substantial appropriate
technological development for this to be successful.

5. Final comment on Pellets:  I am most familiar with pellets, and many
know they are now a major energy commodity in the developed world.  The
downside is that they take much higher electrical or diesel energy input
than simply chipping or splitting biomass.    Also, they require more
capital, and the plants are more complex to operate and maintain.
 Consequently they are less suited for a widely distributed system - like
the existing charcoal production - especially in developing countries.  If
the pellet plants are large then the wet wood is hauled further to get to
the plant and the benefit in comparison to charcoal is reduced.  Still they
are the most uniform, transportable, and appealing of the dried woody
biomass options.  It just remains to be seen which of these different
approaches - pellets, chipped, crumbled, or split dry biomass will develop
more over time.

- Paul


-- 
Paul M. Means
Research & Testing Manager
Burn Design Lab
(253) 569-2976 (mobile)
http://www.burndesignlab.org/
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