<font style="font-family: arial,helvetica,sans-serif;" size="2"><br />
<br /><br />Paal W: "To produce 2,7 kg charcoal you need about
10-12 kg firewood, depending on the kiln. ..." <br /><br
/>Crispin: "There is still a lot of work to do."<br
/>----------------------------------------------------------<br />Oh,
yes, i think there is,<br />i am just here in Palestina for WORLDViSiON
and we built a heavy duty "adam-retort" made with a casted
cement outer case. 4m² volume for the wood chamber. ~1700kg (fresh cut
(there were not able to get dry wood!)) orange wood, left overs from
farms was loaded.<br />about 400kg of good charcoal we received.<br />If
we assume a humidity of 50%, we deduct 850kg of water - means 850kg of
"oven dry" wood transformed to charcoal,<br />Means a perfect
effciciency of ~47% !!!!! (ok, if we assume 40% humidity, we still
have 39%)<br /><br />Or the other way, 120cm of wood height shrinked
40cm, means 80cm of charcoal height, means charcoal becomes 2/3 of wood
volume, good, good too.<br />I am doing a "one-man-job" I wish
a part of the huge research which is given to stoves, could be diverted
to such kind of retorts...<br /><br />Chris ADAM, <br />Industrial
designer + appropriate technologiste<br />www.biocoal.org<br
/>--------------------------------<br /><br /><br /><br />-----Original
Message-----<br />
Date: Wed, 10 Apr 2013 04:54:28 +0200<br />
Subject: Re: [Stoves] Alternative to charcoal<br />
From: "Kevin" <kchisholm@ca.inter.net><br />
To: "Discussion of biomass cooking stoves"
<stoves@lists.bioenergylists.org><br />
<br />
<div style="position: relative;"> <div><font face="Arial">Dear
Dale</font></div> <div><font face="Arial"></font> </div> <div><font
face="Arial">You raise excellent points about the desirability of
finding an "Alternative to Charcoal". I feel that the problem
is both very complex, AND very simple at the same time. The problem is
very complex, when dealt with, as a whole, but very simple when broken
down into the various facets of the issue that complicate
it.</font></div> <div><font face="Arial"></font> </div> <div><font
face="Arial">If we look at the "continuum" between wood as a
fuel, and charcoal as a fuel, we see that at the "Wood End"
and the "Charcoal End", there is a clear preference, need, or
requirement for the respective fuels. In the center, there is a
"gray area", where either fuel can be utilized, to greater or
lesser advantage and disadvantage.</font></div> <div><font
face="Arial"></font> </div> <div><font face="Arial">The problem is
somewhat further complicated by those who see charcoal as a
"climate change tool" and superimpose climate change
considerations on stoves, perhaps even to the degree of relegating the
fundamental heating and cooking aspects of a stove to a secondary level
of importance. </font></div> <div><font face="Arial"></font> </div>
<div><font face="Arial">Everything starts with the biomass fuel... wood,
grasses, agricultural products or waste, etc. In the logic I am about to
lay out, I state that there are fundamentally three kinds of
stove:</font></div> <div><font face="Arial">1: A "Full Combustion
Biomass stove", where all fuel is intended to be burned to
completion</font></div> <div><font face="Arial">2: A "Partial
Combustion Biomass Stove", where char or charcoal is a desired end
product. (This charcoal can be subsequently used as fuel, or as
biochar.)</font></div> <div><font face="Arial">3: A "Charcoal
Combustion Stove."</font> </div> <div><font face="Arial"></font>
</div> <div><font face="Arial">In the interests of simplicity, I ignore
"Charcoal Retorts", because of their basic thermal
inefficiency.... much of the pyrolysis gas energy is simply vented.
However, a retort that made use of the pyrolysis gas heat could be
termed a "Partial Combustion Biomass Stove.'</font></div>
<div><font face="Arial"></font> </div> <div><font face="Arial">A major
advantage of this approach would be that it would clearly categorize
stoves, and as a consequence, would allow for three different testing
protocols.Each Testing protocol could be set up to best capture the
performance parameters that were of most importance to each stove
system.</font></div> <div><font face="Arial"></font> </div> <div><font
face="Arial">Crispin's Proposed Stove testing Protocols are perhaps best
for "Full Combustion Biomass Stoves." Equivalently relevant
protocols could be developed for "Partial Combustion" and
"Charcoal stoves.</font></div> <div><font face="Arial"></font>
</div> <div><font face="Arial">I feel that the process should be
"Customer Driven." If a Customer wants to burn charcoal as
fuel, then that is his decision. Or, if he wants to produce charcoal,
for resale, or for use as biochar, or for subsequent use as a fuel, then
that also should be his decision. This is where a good set of Testing
Protocols would be really helpful... they would allow the Customer to
select the stove system (or systems) that best met his
needs.</font></div> <div><font face="Arial"></font> </div> <div><font
face="Arial">Note also that when fundamental "performance
information" was available from the above three protocols, it would
be very easy to develop a spread sheet that factored in all the relevant
information, so that the Customer could make a rational decision on what
would be the best stove system for his particular
circumstances.</font></div> <div><font face="Arial"></font> </div>
<div><font face="Arial">Best wishes,</font></div> <div><font
face="Arial"></font> </div> <div><font face="Arial">Kevin</font></div>
<div><font face="Arial"></font> </div> <div><font face="Arial"></font>
</div> <div><font face="Arial">. </font></div> <blockquote
style="border-left: 2px solid rgb(0, 0, 0); padding-left: 5px;
padding-right: 0px; margin-left: 5px; margin-right: 0px;"> <div
style="font: 10pt arial;">----- Original Message ----- </div> <div
style="font: 10pt arial; background: none repeat scroll 0% 0% rgb(228,
228, 228);"><b>From:</b> <a href="mailto:dandreatta@sealimited.com"
title="dandreatta@sealimited.com">Andreatta, Dale A.</a> </div> <div
style="font: 10pt arial;"><b>To:</b> <a
href="mailto:stoves@lists.bioenergylists.org"
title="stoves@lists.bioenergylists.org">Discussion of biomass cooking
stoves</a> </div> <div style="font: 10pt arial;"><b>Sent:</b> Monday,
April 08, 2013 6:09 PM</div> <div style="font: 10pt
arial;"><b>Subject:</b> [Stoves] Alternative to charcoal</div> <div><br
/></div> <div class="WordSection1"> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;">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. </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;"> </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;">Their proposed fuel was crumbled wood,
which would work well, but seemed to me to require a lot of big
machinery and capital. How could one go from a tree to a fuel that
would burn well in a gasifier with as little work as possible, and
without too much costly equipment? The fuel should be as low or lower
in cost than charcoal per unit of food cooked, and give a better ratio
of food cooked per unit of tree. </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;"> </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;">I did some preliminary experiments.
With 779 g of natural wood from the trees in my yard, I used a Paul
Anderson Champion gasifier and boiled 5 liters in 21.4 minutes
(corrected). After an easy light the stove burned steadily with no
attention, other than turning down the primary air when boiling started.
About 10 minutes after boiling the pyrolysis ended and I transferred
123 grams of char sticks, glowing only weakly, into a charcoal stove,
and continued simmering until nearly 2 hours after the start of boiling.
I had good turndown on the charcoal stove and a lid on the pot. There
was a little smoke during the pyrolysis phase, but not too much. This
seems like excellent stove performance. </span></p> <p
class="MsoNormal" style="margin:0px;"><span style="font-family:
'Calibri','sans-serif'; color: black; font-size:
11pt;"> </span></p> <p class="MsoNormal" style="margin:0px;"><span
style="font-family: 'Calibri','sans-serif'; color: black; font-size:
11pt;">Had I used a very good charcoal stove to perform a similar task,
it might have taken 240 g of charcoal. This would take about 1800 g of
wood if the charcoal were made efficiently, or 3000 g if it were made
normally. (Reference Means and Lanning on the efficiency of charcoal
production.)</span></p> <p class="MsoNormal" style="margin:0px;"><span
style="font-family: 'Calibri','sans-serif'; color: black; font-size:
11pt;"> </span></p> <p class="MsoNormal" style="margin:0px;"><span
style="font-family: 'Calibri','sans-serif'; color: black; font-size:
11pt;">The wood I started with was about 1 inch diameter (2.5 cm) by 6
inches (15 cm) long, cut from my trees and dried outdoors but under
cover for some months. I didn’t measure the moisture content, but a
previous oven-drying test with similar wood showed about 12-14%
moisture. A previous test with larger diameter wood didn’t go well, so
I think this is about the maximum possible diameter. I don’t know how
long it took to get to this moisture content, not months I’m sure, but
at least some number of days. </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;"> </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;">The production method for this
alternative to charcoal would be to use a chain saw to cut wood into
convenient lengths while in the forest, then take it to a central place.
Here, use electric saws and/or hydraulic splitters to cut the wood to
the appropriate size. Give the wood a modest amount of drying in the
sun, or in some simple oven. The wood might have to finish drying at
the place of use. I expect that split wood would dry faster than cut
sticks, since the moisture doesn’t have to pass through the bark.
Alternatively, use a chain saw and engine powered splitter to cut the
wood to size in the forest, then transport to a central place for
drying. When fairly dry, transport the wood to the users as with
charcoal. During transport, the energy per unit weight would be lower
than charcoal, but the energy per unit volume would be similar. The
user might be given the option of buying shorter sticks for cooking
smaller meals, or longer sticks for larger meals. </span></p> <p
class="MsoNormal" style="margin:0px;"><span style="font-family:
'Calibri','sans-serif'; color: black; font-size:
11pt;"> </span></p> <p class="MsoNormal" style="margin:0px;"><span
style="font-family: 'Calibri','sans-serif'; color: black; font-size:
11pt;">In comparing the economics of this method to charcoal, I would
think of the cost of the fuel as coming from 5 elements; the cost of the
trees, the cost of the processing equipment, the cost of the labor, the
cost of the transportation and distribution, and the cost of the stove.
If the trees are free, then the fact that you don’t cut as many trees
doesn’t help much. If the trees must be paid for, then this method
looks more attractive. The processing equipment for charcoal is
virtually free, but hopefully this method doesn’t take too much
equipment. The labor for this method might be similar to charcoal, but
it might be less because you are cutting and processing a lot fewer
trees to serve the same number of customers. Transportation would be
more expensive, since you are shipping more mass, though not a lot more
volume. This method would require a gasifier or T-Char stove, which
would be an expense, though hopefully not a lot compared to the annual
cost of fuel. </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;"> </span></p> <p class="MsoNormal"
style="margin:0px;"><span style="font-family: 'Calibri','sans-serif';
color: black; font-size: 11pt;">Thus, if the trees must be paid for,
this method might be attractive to the consumer of the fuel, the
producer of the fuel, and to the forest. If the trees are not paid for,
this method looks less attractive, though the forest would still benefit
and some outside subsidy might be available.</span></p> <p
class="MsoNormal" style="margin:0px;"><span style="font-family:
'Calibri','sans-serif'; color: black; font-size:
11pt;"> </span></p> <p class="MsoNormal" style="margin:0px;"><span
style="font-family: 'Calibri','sans-serif'; color: black; font-size:
11pt;">Dale Andreatta, Ph.D., P.E. </span></p></div> <p
style="margin:0px;"> </p><hr /> <br /><br
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