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<div class="moz-cite-prefix">Dale and all,<br>
<br>
Thank you for your input, especially the quantitative parts. I
confirm and agree with your comments, such as about 1 inch maximum
of diameter of wood in the residential size TLUDs.<br>
<br>
I hope that more people will be considering alternatives to
charcoal. <br>
<br>
Paul<br>
<pre class="moz-signature" cols="72">Paul S. Anderson, PhD aka "Dr TLUD"
Email: <a class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a> Skype: paultlud Phone: +1-309-452-7072
Website: <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
On 4/8/2013 4:09 PM, Andreatta, Dale A. wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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.)<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">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.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Dale
Andreatta, Ph.D., P.E. <o:p></o:p></span></p>
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