[Stoves] Alternative to charcoal/ cut to length split on site = "split-wood"
Paul Anderson
psanders at ilstu.edu
Wed Apr 10 09:09:36 CDT 2013
Stovers,
I really like Lanny's explanation and the photo (photo in original
message). Wood that is cut to an appropriate length (a known length
for a specific type of stove) and then split (or split and then cut into
desired lengths).
I will call this "split-wood," to help distinguish it from cord-wood or
wood chips or stick-wood.
I learned from Ugandans to place split wood vertically into TLUD
stoves. Fill it well; not just a couple of loose pieces.
Some data and photos about this are in the Quad 2 Stove Performance
Report <http://www.drtlud.com/2012/10/23/quad-2-stove-performance-report/>
found at http://www.drtlud.com/2012/10/23/quad-2-stove-performance-report/
Shows 3 different sizes (thickness) of the same wood used. Split-wood
works great, and the resultant char is in good-sized chunks.
One difference from Lanny's report (that is based on USA experiences) is
that in many developing countries,
a. most of the wood seems to be branch size, not trunk size.
b. chain saws are not so easily accessible
c. bow-saws for cutting are available, but not necessarily affordable
to all. But in addition for a machete (panga), or an axe, a bow-saw
is the start of making "prepared fuels" or "processed fuels".
Split-wood is not as "prepared" as wood chips, or pellets, or alcohol or
LPG, but split-wood is more prepared than gangly branches dragged in
from the hillside and stuffed into 3-stone fires.
There is still a lot of work to be done about fuel supplies.
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: psanders at ilstu.edu Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 4/9/2013 10:29 AM, Lanny Henson wrote:
>
> Dale and Stovers,
>
> How about wood cut to a length, that works for a typical household
> stove, maybe 3 to 6" long, it could be a large diameter or a small
> diameter, and let the end user split the wood to the right size for
> their stove, with a hatchet.
>
> Wood dries quicker when cut to a shorter length and it is easy to
> split, easy to handle, and easy to weigh, and the wood is more compact
> to ship, also the wood dries quicker.
>
> I have been burning red oak, pallet oak, spruce 2x4 and limbs cut to
> about 6" long, and split to size with a hatchet. I used a chain saw
> for the disk and a hand saw to cut the limb and 2x4. If the wood is
> longer than you need, and you do not have a chain saw, split the
> wood first and then use a hand saw to cut it to length. I usually cut
> a typical "fire wood" length in 3 pieces.
>
>
> Wood, Short Lengths, Split to Size.
>
> Lanny
>
> ----- Original Message -----
> *From:* Andreatta, Dale A. <mailto:dandreatta at sealimited.com>
> *To:* Discussion of biomass cooking stoves
> <mailto:stoves at lists.bioenergylists.org>
> *Sent:* Monday, April 08, 2013 5:09 PM
> *Subject:* [Stoves] Alternative to charcoal
>
> 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.
>
> 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.
>
> 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.
>
> 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.)
>
> 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.
>
> 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.
>
> 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.
>
> 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.
>
> Dale Andreatta, Ph.D., P.E.
>
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