August 18, 2010 | 5
Editor’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 fifth blog post for Scientific American.
The water taxi edged past the final jungled outcrop of Gombe Park in Tanzania. As we crept away from the park towards civilization, the monkey-filled trees of Gombe faded into burned out hillsides replete with palm oil trees and dust. It was in this scarred land that I caught a first glimpse of the village Mwamgongo: my home for the next two months.
My initial description of Mwamgongo might lead you to think that it is an ugly wasteland: a product of Tanzanians’ reliance on wood for the majority of their cooking and energy needs, which has resulted in widespread deforestation throughout the country. The opposite is true. Mwamgongo is actually one of the most beautiful places I have ever been, but there is a stark contrast between the natural lushness of the impenetrable array of vine ridden foliage found in Gombe Park and the grassy hillsides that replace it in Mwamgango. This disparity is magnified by the lack of rain, which has allowed the relentless sun to burn the grass into a dusty golden color. The dry season extends from late June to September and we are in the thick of it.
After the initial shock, the beauty of Mwamgongo is inescapable. The crystal clear turquoise waters of Lake Tanganyika lap at the base of white pebbled beaches, precisely manicured for drying Dagga, small sardine-like fish that Mwamgongo relies on for subsistence and export. The village itself extends back into the mountains dotted with mud brick houses that melt into the hillside. The oil palm trees, which at first seemed like garish evidence of human exploitation, could be on a postcard from paradise.
I am one of two returning veterans on this trip; I spent two months in Mwamgongo the previous year working on the same project: introducing cookstoves that burn cleaner while using less wood. The design we have been propagating is called the rocket stove. It takes advantage of the fact that 70 percent of the heat energy you get out of a piece of wood when it burns is from the heat-activated gasses that vaporize off the wood (that’s what’s happening when you see flames). The rocket stove has a short (30-centimeter) combustion chamber that concentrates the gasses coming off the wood producing a tall flame that reaches from the wood to the bottom of the pot, limiting radiation losses and permitting more efficient heat transfer. The firewood rests on a metal shelf that allows air to rush under the wood and propel the flame and hot gasses to the cooking pot at a high velocity. In addition, the metal shelf gets very warm, which preheats the air that approaches the fire. Fire is the combustion of fuel (the gasses coming off the wood) and oxygen. By preheating the air, less energy is wasted and the fire burns hotter—hot enough to burn off many of the particulates and CO (carbon monoxide) that are normally emitted. The result: a nearly smokeless fire that burns wood at a rate of 20-to-25 percent thermal efficiency. We built the stove using locally available clay and mud cement bricks at a material cost of less than $2 per stove.
Unfortunately, we were competing against the three-stone stove. The three-stone stove is a wood-munching monster that burns at 7-to-10 percent efficiency and produces enough eye watering, acrid smoke to make you never want to step foot in another Tanzanian kitchen. But what the three-stone stove lacks in performance, it makes up for in tradition. For countless generations, people have used the aptly named three-stone stove: literally three stones that support a pot over an open fire. Because traditions tend to die hard (especially in a place that is accessible only by boat with no cell phone or Internet access), the three-stone stove handed us a pretty severe "beating" for the first year of the project. We built 25 stoves, but post implementation assessment revealed they were not heavily used and there was limited dispersion of the technology. People preferred to use their three-stone stove.
The stagnant results of the previous year were running through my mind as I grabbed all my bags and teetered along the thin walkway of the boat, managing to lose my balance only once, much to the enjoyment of the rest of the Tanzanian passengers. For anyone who hasn’t traveled in Tanzania before, humor in the face of misfortune is completely standard, and once you get used to it, pretty funny. I put on a goofy smile—my standard response to being laughed at—and I hopped off the boat while hundreds of children, who had assembled to see the new visitors arrive, chanted "Mzungu" (European or white person) and "nipe hela" (give me money). I am traveling with fellow Dartmouth students Wendy Hado and Kanika Searvance, who being of African descent and dressing the part, blended in until they tried to speak Swahili or picked up their bulging backpacks (calling cards of a Mzungu). It was their first time here, but I knew that they would adjust quickly.
Thankfully our cook and Jane Goodall Insitute (JGI) field station housekeeper, Chaco Kheri, was there to rescue us from the crowded chaos and whisk us away to our home. Although we didn’t have electricity or running water, I don’t want anyone to get the impression that we were really "roughing" it here. Not only is the field station spacious and comfortable, Chaco is an amazing cook who prepares rice, beans and fresh fish for us every day. She also provides an incredible spark of life to the place. I’ve seen her physically fight over the price of fish and laugh for what seems like hours on end. The memories of the place and the people were flooding back in full force. I remember thinking as I flopped down on the mattress exhausted from the day’s travel, "At least this year I kind of know what to anticipate," which really meant expect the unexpected.
Image courtesy of Kyle Betts