[Stoves] Alternative to charcoal

[Crispin Pemberton-Pigott]

Dear Dale and Friends

 

The analysis of alternatives to charcoal should include the reasons why
people prefer it, strongly, over wood when given a choice of either, with
charcoal costing much more than wood per kg. Working out theoretically how
to burn all the wood (which is what burning gases+burning char is doing)
doesn't really address the reason why people don't want to burn wood if they
have enough money - in other words if they have a choice.

 

Once it is admitted that burning wood gas then char is the same as burning
whole wood as far as the forest is concerned, we can also admit that
transport and convenience have a lot to do with it. In other words, this is
a question strongly influenced by social questions.

 

The transport of charcoal (MJ per ton-mile) is much cheaper than
transporting wood and this difference dominates the charcoal economy. It is
impractical to ship wood 600 km in Mozambique because of cost of doing so.

 

In order to get the comparisons right I feel we need to agree on some
definitions. The wood can be dried in the field. The energy content can be
taken to be about 15 to 16 MJ/kg. Charcoal can be taken to be 29 MJ/kg or
about double the energy. Mental arithmetic becomes easy.

 

Decent charcoal production (improvement of the source technology, not only
the stove technology) should be considered because it is a heck of a lot
cheaper to improve the production than to improve every single stove in all
sizes everywhere). What I mean by this is that if we seek systems type
improvements we should consider all the systems involved. In a way it is
like the 'open fire' as the baseline. It does not help the analysis to seek
really bad examples of open fires then compare the 'improvement' to it.
Just a caution.

 

One way to analyse this is to look at how the biofuel energy supply is
already emerging. The shipping of wood pellets and torrefied wood shows
there are ways to attract 'custom' selling packaged energy. A stick of wood
is a package of energy.

 

I want to add one comment about the cost of the products. I tested recently
a TLUD pellet burner that by opening a small door, burns the charcoal
afterwards. The gas flame was not as controllable as the charcoal one but
that is a quibble. There was no need to transfer anything, it was just a
sequential burner. The market price is $5.50 and the production cost is
$2.20 or so. That is with a metal shell. With a clay shell it would be about
$1.40 to make. I think that is cheap. I will process the test results to see
what the performance in numbers was like.

 

Pellets are a processed fuel and can include non-woody biomass. China is
making millions of tons of them from agricultural waste with an aggressive
expansion plan that include developing better and more efficient equipment.
That may be the charcoal replacement of the future, provided people are
willing to use them and the stoves deliver the cooking and heating
experience they seek.

 

Regards

Crispin

 

On 4/8/2013 4:09 PM, Andreatta, Dale A. wrote:

At the recent ETHOS conference Paul Means and Chris Lanning gave a very
thought-provoking talk about an alternative to charcoal.  The basic idea was
to use a gasifying stove with prepared wood fuel.  The prepared wood fuel
would be bought by the user instead of charcoal, and the supply chain would
be similar to charcoal.  The big advantage is that the very inefficient step
of charcoal production is eliminated.  The stove would hopefully be easy to
use and would smoke very little, so as to retain the benefits of a charcoal
stove.  

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20130409/45498dbf/attachment.html>