Monday, March 12, 2012

Rocket Stove Failure?

      Last December, during the bi-annual permaculture design course held a Nyumbani Village (which I attended), we built a wonderful rocket stove in the outdoor kitchen of a house in cluster 3 of the village. Using all locally available materials, we custom-made this rocket stove to fit the pots of the household. Rocket stoves are much better for the environment as they create much more fuel-efficient fires compared to the three stone fire stove thus reducing the fuel wood demand. They also produce less polluting gases and smoke, which is healthier for the cooks, and they are much safer to use than the stoves that are currently used. At the beginning of the year I checked in on the family to see whether they used the rocket stove over their conventional fires and was happy to see a pot of rice boiling away on the stove. After asking a few questions as to how the stove is operated, who operates it and how often it is used, I went away happy knowing that our project worked.

the traditional three stone fire stove (with an additional wind break) on the left and the new rocket stove on the right
      Earlier in the month of March, I decided to check up once again on the stove to see how things were coming along. Heading over in the evening, I was sadly greeted by an abandoned rocket stove and next to it, a three stove fire burning happily with a pot of beans atop it. No one from the family was in sight of the stove so I knocked on the door. Two young girls that I recognized as the cooks of the house emerged looking a bit nervous. After doing the usual greetings I began to question them about their preference for the open, three-stone fire stove as opposed to the rocket stove. Having to re-phrase my questions a couple times to get the answers I needed I finally understood their reasons for abandoning the rocket stove. To begin with, the rocket stove requires much more attention during cooking than the open fire. The space to place the fuel wood is small, which enhances the efficiency of the combustion but also requires the cook to hang around feeding the fire with smaller pieces of wood. Clearly it was easier for the girls to put a huge hunk of wood in the open fire, set up their pot, and forget about it. After a long day at school, they were more inclined to spend time socializing as opposed to hanging around a stove feeding a fire. The rocket stove also required fuel wood of a certain shape and size. Given that the children are responsible for fetching firewood and this task can take up to five hours at a time, the children weren’t too picky in which pieces of wood they brought home as long as they finished their chore in the shortest amount of time. The girls insisted they used the rocket stove for meals that take a short time to cook and they proudly stated they cooked chapatis (a flat bread and staple of Kenyan cuisine) on the rocket stove. When questioned as to how often they cooked chapatis, they admitted to once a year, when they are given chapati flour for Christmas (chapati flour is relatively expensive). Given that their diet consists mainly of maize and beans, ingredients that take an excruciatingly long time to cook, their explanations implied that the rocket stove went pretty much unused.

     Disappointed by the result, I was happy to learn about their cooking needs and preferences of the household and how each stove worked (or didn’t work) for the household’s lifestyle. The rocket stove completely ignored these factors in the design and this is probably part of the reason why they are difficult to implement and fail after a period of time. As I walked away, I thought to myself, instead of designing new stoves for the families it may be worthwhile instead to refurbish the current stoves the families use to improve their efficiency, safety and environmental impact. Yet another project for volunteers to explore in the village!


  1. Interesting - I hadn't considered the time/attention factor before. So, how do you get a large flame to more completely combust wood?

  2. Disclaimer: I have no idea what I'm talking about. But, I would assume its the "open" part of the flame that causes the loss of energy. Seems like a larger rocket stove that held more fuel would do the trick... perhaps the size would become unwieldy though. Maybe you could dig the combustion chamber into the ground?

  3. digging the combustion chamber into the ground could possible work. The less air that gets into the combustion chamber the more efficient the burning, this is why the space for wood is so small.But too small a space and no one uses it. I guess we need to play around with different sizes to see which one is the best compromise.

  4. heavy duty shower pumps
    New ranges for the family members it may be beneficial instead to remodel the present ranges the family members use to increase their performance.