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Burn, baby, burn: Student-engineered stoves put to the test by Tanzanian women


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Dartmouth, stove, cookingEditor’s Note: Students from Dartmouth’s Thayer School of Engineering are working in Tanzania to help improve sanitation and energy technologies in local villages. This series chronicles work being done by the student-led group, known as Humanitarian Engineering Leadership Projects (HELP), to design "rocket stoves" in the village of Mwamgongo and top-light updraft design (TLUD) gasification stoves in the village of Kalinzi. The goal is to create a healthier, more energy-efficient cooking apparatus that these villagers will accept and use. HELP students are filing these dispatches from the field during their trip. This is their ninth blog post for Scientific American.

Our rooster, the infamous "Clyde," woke us with his usual loud and somewhat garbled crow to get us to work delivering stoves to the six women who had volunteered to provide practical feedback. As we introduced each of the women to their new stove, and explained how to use it, we were met with an overwhelming wave of gratitude. Our neighbor was so excited when she got her stove that she jumped up and started dancing. It is immensely rewarding to have our work met with so much appreciation, but there is a small risk that our testers’ enthusiasm will keep them from telling us all of their problems and criticisms. Only time will tell.

Efficiency testing and experimenting with different coffee husk burning strategies took up most of our afternoon and yielded some thought provoking results to build upon. We evaluated several packing methods and different inserts, and our most hopeful lead came from a perforated tube inserted vertically in a bed of coffee husks to emulate a sawdust stove. It wasn’t perfect, but it was promising.

As we were preparing for our last test of the evening, our friend Fundi decided to stop by for a little socializing. He was very impressed by the quality of our stoves, and refused to believe us when we insisted that we had designed them ourselves. He also couldn’t make sense of the metal bin we had made out of roofing metal to hold our coffee husk supply and chopped up firewood. From what we understood of his Swahili, he thought it was a baby’s cradle, and he rebuked us for having so many sharp edges.

On another note, the barabara (road) in Kalinzi has progressed rapidly, and we can occasionally feel the ground shaking as the steamrollers pass back and forth. Paving seems to be imminent and will bring a welcome end to the enormous dust clouds that currently waft up after passing cars and trucks. We’ll see what else it brings.

We have been working to find a good way to assess how our stoves compare with the currently omnipresent three-stone stove (mafiga matatu). Thus far, cooking with the women has helped us to see how our stoves are being used and has given us a better sense of the efficiency of our stove over the duration of cooking an entire meal. This metric provides a more practical evaluation of efficiency than a more conventional "water boil test," which only indicates short-term performance of a stove by bringing a liter of water to boil.

When we perform our cooking tests with women, we measure out piles of wood by both our stove and the three-stone stove, and measure an even amount of food to be cooked on each. When the food is done, each pile of wood is weighed again, and then the total mass consumed from each pile is compared. In our practical testing so far, we have seen a range of improvement ranging from 20 to 40 percent reduced wood use, depending on wood type and moisture content. Our current average is roughly 33 percent.

We still have some issues to work out, but these savings let us know we’re doing something right. We still need to find a way to reduce the smoke that occurs when new fuel is added, and find a way to reduce the amount of tending required to use our stove. Seeing the two stoves side by side, our stove requires at least three times more frequent fuel addition than the three-stone stove since it uses smaller pieces of wood. Our next iteration of designs will be aimed at addressing these problems.

For all that we have learned by performing our practical cooking tests, we have learned perhaps more by the experiences surrounding our tests. The duration of our testing process means that we are in these Tanzanian households long enough to melt into the background a bit and see a glimpse of what daily life here looks like. An anthropologist would probably say that it is impossible to observe without affecting—and they’re probably right—but the experience is incredibly informative nonetheless. We have even had the honor and privilege of being invited to eat with the women following our tests on a few occasions and have been thoroughly impressed by the hospitality shown by Tanzanians. From laying out a straw mat for us to sit on, presenting us individually with a washbasin and soap to clean our hands, and explaining how to properly eat Ugali (a very "hands on" communal food), dagaa (whole fish), and mchicha (veggies similar to spinach), we get nothing but welcoming smiles and minimal laughter at our faux pas. The near ceremonial invitation by the host: karibuni chakula (or "welcome to the food") both encourages a wrists-deep dining experience and seems to sum up the emphasis put on hospitality and sharing food. Food—and the practices associated with dining—provide great insight into the cultures of a people; our experiences with the gastronomy here have shown that Tanzanians excel at kindness, generosity and cooking.Dartmouth, Clyde, Tanzania

In other news, Zach and his translator Revo joined us for a few brief and productive days. Within the first afternoon of being here, Revo, who is a native of Kalinzi, found clay and inspired us to consider a rocket stove project in the village. (We previously thought clay was non-existent in the area.) Zach also introduced the idea of showing people how to build a "haybox," a passive cooking method that insulates food after brief heating and has the potential to significantly reduce fuel consumption. This idea is particularly interesting to us because no matter how efficient we can make a stove, a cooking method that requires less time on any stove is a versatile and promising way to reduce fuel usage.

It is both a blessing and a curse that there are so many potential and promising technologies that could make positive changes here. There are many avenues of improvement, but the myriad of ways to do it causes us to spend lots of time wrestling with the paradox of choice. Days fly by and our eight weeks here feels continually smaller. It would be great if HELP could operate here 12 months a year—and maybe that will happen in the future—even though we are just student-led organization.

Images of stove and "Clyde" courtesy of Wendy Hado and Tim Bolger, respectively





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Comments 4 Comments

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  1. 1. jctyler 11:51 am 09/8/2010

    Right ON!

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  2. 2. eco-steve 12:28 pm 09/8/2010

    Plug any holes in the base of the stove to stop air getting in, light the wood and put on the perforated lid. Now you have a pyrolyser which will convert the biomass into charcoal, giving off hydrogen for the cooking, so no smoke, only water vapour as exhaust. Grind up the charcoal and dig it into your soil to improve water retention meaning less watering needed. Pyrolysis is the overlooked technology of the hydrogen economy.

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  3. 3. zinn 9:44 pm 09/8/2010

    Good point Eco..

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  4. 4. tichead 10:49 pm 09/8/2010

    This is hot! Got any schematics of the stoves?

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