Crispin,
Do you think it is useful to place a value on the reduced life span of a
$5 TLUD when burning char compared to the same TLUD not burning the char?
Alex
On 08/04/2013 9:30 PM, Crispin Pemberton-Pigott wrote:
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.
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