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.

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.

Demolition of Shed and operation of Greenhouse; Notes from the Work Days March 20th and March 23rd

There was an old run in horse shed on the urban farm property. Due to age and improper construction, it was beginning to fall apart, and was, in any case, too small for our purposes. So we decided to pull it down, salvage what lumber we could, and build a new shed.

Here are some pictures of the project.

The shed as it was, a few months ago.

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The walls starting to come down. We still have to remove all the stuff that had been stored in the shed over the years.

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The roof collapses after being disconnected from  the back posts.

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After this point, we used a vehicle to pull down the front posts which the roof was leaning on, dropping it to the ground. (Unfortunately, we did not get a picture of this step.)

At the next meeting (March 23rd) we broke up and cleared away the roof and other debris, and dug out the posts.

At these meetings we also eliminated poison hemlock from the areas where we will be working, and tidied up the property. Our greenhouse vent arm seems to be working well, and lettuce is growing inside. As you can see, there was still some snow on the ground from the most recent fall, but the temperatures inside the greenhouse were warm and steamy, triggering the vent’s arm to pop open. At the next meeting we hope to plant Brassicas and other cool weather crops in the greenhouse for transplanting to the main gardens in April.

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Greenhouse Construction Phase Two/ Notes from the Meeting of December 18th

At this meeting we got our greenhouse much nearer to completion— the plastic cover is now in place. We pulled it over the frame, and then rolled the edges around some scrap metal pipes, which were buried in shallow trenches along the sides. This should help to keep the plastic in the ground. We then cut short sections of black plastic pipe, slit them down one side, and used them to clamp the plastic to the end hoops. (Here is a link on an earlier page, where it describes the first phase of the greenhouse construction. Greenhouse construction )

Here are some pictures of the greenhouse.

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We still have to tighten the plastic a little, and put some duct tape under each clamp to stop them from abrading the cover. Then we have to modify and place a door, and attach it to the frame. We left the plastic cover loose at the west end, so that the door can be put into place. We will then attach the plastic tightly to the west end hoop. (Right now it is weighed down with landscape timbers.) We also have to frame a vent and attach an automatic vent opener, insulate the north, east, and west sides with bubble wrap, and pile a little more earth around the edges. After that, we can begin to instal hot frames and thermal mass.
The thermal mass will be large, black containers full of water. This will act as a sort of flywheel, absorbing the extremely high temperatures during the day, and releasing the extra heat at night to keep the greenhouse warm. Without any mass, the greenhouse would cook plants during the day, but rapidly freeze at night if the outside temperatures are much below thirty-two degrees.
The hot frames will be a second translucent structure inside the greenhouse. They will be sunk below ground level and insulated. Since they will only be exposed to the moderated conditions inside of the greenhouse, they will keep a fairly stable temperature. Extra heating will be provided inside the frames by means of compost and or electricity. For low cost electric backup heating, we could use an infrared bulb or a heat cable. These would be set to come on only if the temperature dropped dangerously. The hot frames will be used to start seedlings in the spring.
We also discussed remodeling the run in horse shed on the property to store tools and equipment, and our mason bee project. The shed remodel will probably be our next project.

Greenhouse construction, Phase one/ Notes from the meeting of December 3rd

At this meeting we got the frame of our Greenhouse put up. We bent inserted lengths of rebar into PVC pipe, and bent the rods into hoops, inserted about a foot into the ground. We then joined them at the top with another length of PVC/ rebar. The rebar provides the strength, and the PVC keeps the rebar from abrading the plastic cover. S30A0132

Due to the wind, which picked up towards the end of our meeting, we were unable to get the plastic cover attached. It would have been buried along the sides of the greenhouse. We also need to build a wooden frame at one end to contain a door and vent. Once we get this done, we will install an inner hot bed for starting seedlings, low tech insulation on the north side, mass to collect solar heat and even out temperature swings, and possibly a compost heating system. These systems will be backed up by an electric heater.