Thursday, February 19, 2009

Rocket Stove

So this rocket stove, aka mud stove, aka “estufa lorena” “estufa mejorada” is a pretty awesome thing. There are many designs (not all use mud) based on this way of insulating the flame and creating a vacuum with a chimney, so the heat is directed only to the pot of food, and thus food cooks faster and hotter (THIS is why it´s called a rocket stove...things cook ¨rocket¨fast), and less wood is burned. So clearly, there are real benefits. Less looking for firewood (super scarce). Faster cooking. Cooks are more comfortable because the flame is within the insulated “fire box” section, and the smoke goes up and out the chimney. I like the idea that food doesn’t taste like smoke.

So first thing we did was build a packed-dirt base lined with metal beam scraps and held in place with cinder blocks. This base would make the stove land at about the right height for cooking (starting from the table would have ended up with a way too high cooking surface).

Then we mixed red dirt, sand, and a little bit of straw with water to make the mud mix. The dirt is full of clay, which acts like cement, I forget why we needed the sand other than you always mix it with cement, and the straw was for strength. If you’ve ever heard of ferro-cement building, this is the campo version. Yes, we mixed it in a big hole with our feet. I had a great time.



We made a form out of wood. This was the hardest part, finding straight wood slabs in town, which we could cut to size. I was most worried about this step actually.

The form was secured down to the base with wire. Then we threw fistfuls of the mud mix into the form, packing down very short layers. Throw, throw, pack, pack. The kids enjoyed this part. It took a while to build up 18 inches. We decided to let it dry for about 2 hours before the carving step.

We carved out a hole for the pot. When the pot sits slightly inside its hole, hot air does not escape around the edges, is concentrated underneath the pot, heating it efficiently. There was the “firebox” section, which is a large carved out part where the wood will be loaded and burned. From the burning wood, hot air (ok, smoke) travels to under the pot, and then out the other side of the pot hole, into another channel which leads to the chimney. The chimney’s vacuum helps keep the fire burning hot, but I don’t know how to explain why. We still have to put up the chimney and seal around it before cooking. In the photo there is a cinder block supporting the bridge over the firebox section—our mix was still a bit too wet and we didn’t want cave-ins.



All done!


Now we gotta wait a month to use it. Talking to people in later days, I learned that they enjoyed the experience and seems like we will be building a few more. Now the question is whether I work as a one-woman act, just me working in each house, or if I attempt the ever more stressful but definitely better idea of getting a larger group to work at each individual´s house.
















2 comments:

JSL said...

That is really sweet. Next you can do the Viking version - six pot holes and a griddle!

Flaming Curmudgeon said...

I want one! Something tells me you love to play in the mud and it's just a coincidence that that is also how to make a rocket stove. UK