Rocket and TLUD cook stove experiments

The Saint Isidore Society has been building small cook or camp stoves out of salvaged cans.

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(Pictures of our TLUD stove No. 2)

So far we have built four stoves: rocket stove 1, which was almost exactly like this instructable; it used four soup cans and a #10 can, and vermiculite as insulation; rocket stove 2, which was like number one with a chimney twice the height; a small biochar TLUD stove out of a soup can and another, slightly larger can, which was rather like the one on this site; and a larger and more robust TLUD.

Before I get into the results of our stove experiments, I will give a brief description of the principles behind each kind of stove.

Rocket stoves utilize abrupt right angle bends, an internal insulated chimney, and certain critical proportions to create an extremely efficient, nearly smoke-less burn. They can keep a few small sticks burning for a long time, unlike an open fire.

TLUD biochar producing stoves heat biomass in an oxygen poor environment, producing wood gas, the volatile components of organic matter. This gas is then mixed with preheated air, which produces a clean, efficient flame. They can burn agricultural waste, pine needles, etc., unlike a rocket stove.

Our rocket stove 1 burned cleanly, though it did produce a little smoke, especially when starting off. It boiled two cups of water in a covered pot in ten minutes. (For comparison, an electric stove with a glass top boils water in about six minutes.) We also toasted some marshmallows.

Our rocket stove 2 burned faster then number 1, and also produced some smoke. It boiled two cups of water in five minutes. However, we used two cotton balls dipped in alcohol to start this, and there was probably still some alcohol burning when we put the pan on. This may have skewed results. The first stove’s cotton balls had burned out a long time before we put the pot on, so those results are reliable.

The TLUD stove burned a soup can full of pine needles for about ten minutes, completely charring them all. It produced a hot, clean flame, but we did not try to boil water. The alcohol cotton balls we used to start it burned for ten minutes before the needles started to char. (In a TLUD the starter sits on top of the fuel and the charring moves down through it.) The small amount of pine needle biochar produced was not worth doing anything with.

We built another biochar stove out of two cans, (TLUD 2) a good bit  larger then the first one, and loaded it with wood. It burned well for twenty minutes with no smoke, but then went out abruptly, producing a lot of smoke. When we put it out and dumped it, we found that it had only charred the wood about half way down the can, so it probably could have kept burning for a while. The gas flame was beautiful, and looked just like a propane burner.
We did some research and found a few things that might have put out the stove prematurely. The fuel was too tightly packed, and unevenly loaded; a taller chimney would have drawn in more air; it should have been shielded better from the wind. So we tried again, this time loading the fuel until it could just barely rattle when we shook the can (the last time we had really wedged the fuel in), we put another can on top as a chimney, and we stacked bricks around it to keep the wind off. This time we got twenty-six minutes of clean flame and no smoke. When the fire went out we were left with about a cup of biochar, which we will use for potting mix.

Next we will retry our experiment on rocket stove 2 without the alcohol effect, and outfit both rocket stoves with shields to direct more heat to the pots. We will be building a larger and more robust biochar stove fuelled with wood instead of pine needles. We will probably be experimenting with larger rocket stoves and with a haybox cooker used in conjunction with rocket or TLUD stoves.

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Advent wreaths

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The Saint Isidore Society recently held an Advent wreath fundraiser at Our Lady of Mount Carmel Catholic parish in Littleton. Families payed to gain access to the event, and were given all the materials to construct an Advent wreath, and assistance if necessary. The pine cones and greenery had been collected a week earlier on a member’s mountain property. Participants also received a prayer booklet for the days of Advent. The Saint Isidore Society volunteers served refreshments and helped with the setup and cleanup. Everybody had a great time, and we will probably repeat this next year.