Research, Development and Commercialization of the Kenya Ceramic Jiko and other Improved Biomass Stoves in Africa (pdf)
Dan Kammen, UC Berkeley
Solutions Site Case Study
Kenya Ceramic Jiko References
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Cookstoves in Kenya
A case history that traces the progress of stove development from early misstep to ultimate acceptance can be found in East Africa. Almost one million households now cook with the Kenya ceramic Jiko. The Jiko--the word means "stove" in Swahili--consists of a metal casing with a ceramic lining that helps to direct 25 to 40 percent of the heat from a fire to a cooking pot. KENYA CERAMIC JIKO (left) increases stove efficiency by addition of a ceramic insulating liner (the brown element), which enables 25 to 40 percent of the heat to be delivered to the pot. From 20 to 40 percent of the heat is absorbed by the stove walls or else escapes to the environment. In addition, 10 to 30 percent gets lost as flue gases, such as carbon dioxide.
The traditional metal stove that the ceramic Jiko replaces delivers only 10 to 20 percent of the heat generated to a pot, METAL STOVE (left), a traditional cooking implement, directs only 10 to 20 percent of the heat to a pot. From 50 to 70 percent of the heat is lost through the stove's metal sides, and another 10 to 30 percent escapes as carbon monoxide, methane and other flue gases.
whereas an open cooking fire may yield efficiencies of as little as 10 percent. OPEN FIRE (left) used for cooking in the millions of rural homes transfers heat to a pot poorly. As little as 10 percent of the heat goes to the cooking utensil; the rest is released to the environment.
he first improved stoves began to appear in the early 1980s and were designed by aid groups such as UNICEF and CARE-Kenya. The response from stove users was mixed at best. The designers, mainly natives of the U.S. and Europe, two havens of consumerism, had forgotten the first thing about marketing. Field testing was all too brief, sometimes with pathetic results. In one of the first models, the stove's opening did not match the size of most pots.
Even more fundamental problems plagued some of the early prototypes. Designers acted as if it would be an elementary exercise to improve the efficiency of the common metal stove, a deceptively simple canlike enclosure into which charcoal or wood is fed and ignited. In fact, after much trial and error, it turned out that an extensive investigation of stove physics and engineering design was needed. This analysis revealed that the largest loss of heat from the fire, about 50 to 70 percent, occurs from radiation and conduction through the metal walls. Makers of some of the first stoves took measures to deliver more of the fire's energy directly to the pot. They sometimes accomplish their job a little too well.
The design for one early improved Jiko model emerged after an aid group named the Kenya Renewable Energy Development Program sponsored a research trip to Thailand to inspect an improved stove--the Thai bucket. The resulting Jiko design had inward-sloping metal walls, like the Thai stove, as well as an insulating liner made of ceramic and a mica called vermiculite. The liner was cemented from the top to the bottom of the inner surface walls. It caused excessive amounts of heat to be retained inside the tapered vessel. Metal fatigue resulted from exposure to the trapped hot gases, which caused structural segments to crack.
An initial round of field tests did not provide enough feedback to stop this first-generation improved Jiko from reaching the market, where it received an equivocal response from purchasers. Various governmental and international aid groups, however, continued to work with a loose consortium of craftspeople, called Jua Kali, or "Hot Sun," to try to rectify the problems.
Better stove designs gradually came about during the mid-1980s. At that time, a number of academics began to publish serious analyses of optimal stove combustion temperatures and of the insulating properties of the ceramic liner materials. One of the most notable contributions to enhanced design came through the responses of several women's organizations that had formed around such issues as community health and protection of the environment. These groups were part of a feminist movement spreading throughout the developing world. In Kenya, it was women who suggested recasting the metal bucket design, with its unstable narrow base, into an hourglass shape.
That alteration prevented the new stove from tipping over, a constant danger when food was vigorously stirred in the Thai-influenced, bucketlike implement. It also meant that the insulating liner need extend only from the upper lip to its narrowest circumference at the stove's middle--and the tapered shape let the liner rest stably cemented to the upper metal walls without falling into the stove's bottom cavity. Because the liner covered only half the stove's interior, it did not cause the overheating and consequent cracking that had plagued the early versions.
These design changes, along with extensive training programs established by aid groups and women's organizations, caused dramatic gains in acceptance for the more efficient stoves. Schools, churches and businesses were among the first owners and helped to spark the interest of individual buyers. Today hundreds of Jua Kali manufacturers provide stoves to some 20,000 purchasers every month.
Benefits of the Jiko
The ceramic Jiko has had a considerable impact on household finances. Typical savings of 1,300 pounds of fuel a year frees up about $65 per household--up to a fifth of the annual income for urban dwellers. Women have benefited in that they control a disproportionately small share of family income yet are the primary purchasers of fuel. The Kenya ceramic Jiko has improved their lot in important ways. Many have invested the savings from reduced fuel purchases in small businesses or school fees for their children.
Currently more than half of all urban households in Kenya own the ceramic Jiko, and purchasers range from the poor to the affluent. The concentration of demand in urban areas points up another difficulty with the early stove programs, which commonly targeted users in the countryside. Programs outside the cities, where more than 70 percent of the Kenyan population lives, seemed justified because they met the needs of the poorest segment of society. But the $2 to $5 stove price proved too high for many households that had the option of collecting their own firewood and cooking over open fires. For city dwellers, who sought ways to cut their unavoidable fuel costs, more efficient stoves held a greater allure.
Establishing an infrastructure for stove production has begun to benefit the masses who life outside the city. Village residents have little ability to pay for a ceramic Jiko that may cost up to $5. But they may be willing to spend something less than that amount, some observers reasoned. After all, there are undeniable benefits for an implement that will diminish the drudgery of collecting wood for hours on end and that will reduce the acrid smoke in cooking huts. The smoke can cause exposure to particulates at 20 times the level that the World Health Organization considers a serious health risk.
Success of the ceramic Jiko in Nairobi and Mombasa did not go unnoticed by many of the women's groups that had organized in rural areas. An alliance developed between leading government and aid organizations in Nairobi and women's groups, most notably Maendeleo ya Wanawake (literally "Women's Development"). From these efforts has come a simplified and affordable variant of the ceramic Jiko.
The Maendeleo stove borrows the insulating element from the ceramic Jiko without the metal outer covering. The ceramic liner is set down in the middle of the open fireplace; it is then reinforced with mud and stones. A pot placed atop the stove heats almost as quickly as one on a Kenya ceramic Jiko. Indoor smoke is reduced considerably through more efficient combustion. Further, a Maendeleo stove is usually placed near a wall of the hut so that smoke can climb along the wall and exit more easily.
The Maendeleo stove costs as little as 80 cents; more than 100,000 of them have been disseminated so far. This rural success story helped to spawn a third-generation cookstove, the Kuni Mbili ("two-stick") stove, which has a larger firebox to accommodate wood instead of the charcoal typically used in urban settings.
The Kenyan program has been emulated in a number of other African countries, where the improved stoves continue to gain popularity.
-- about the Author --
DANIEL M. KAMMEN joined the Energy and Resouces Group faculty at the University of California, Berkeley in 1998 as Associate Professor of Energy and Society. After undergraduate (Cornell, 1984) and graduate (Harvard, 1986, ‘88) training in physics, Kammen was the Weizmann & Bantrell Postdoctoral Fellow at the California Institute of Technology where he moved from working on computational physics and biophysics to energy, environment, and development. Following two years at Harvard as a Lecturer in Environmental Change and Risk Assessment, Kammen moved to the Woodrow Wilson School of Public and International Affairs at Princeton University where he directed the Science, Technology and Environmental Policy Program. He has been a Visiting Lecturer at the University of Nairobi, and is a Permanent Fellow of the African Academy of Sciences where he directs a field research and training program on energy and sustainable development in Africa. His research interests include: the science, engineering, management, and dissemination of renewable energy systems; health and environmental impacts of energy generation and use; rural resource management, including issues of gender and ethnicity; R&D policy, climate change, and risk analysis. He is the author of over 70 publications, a book on environmental, technological, and health risks, and numerous reports on renewable energy and development. He has been featured on radio and television and in print as an analyst of energy, environmental, and risk policy and current events. Kammen received the 1993 21st Century Earth Award, recognizing contributions to rural development and environmental conservation. Information on his research, publications, teaching and policy work is available at: http://socrates.berkeley.edu/~kammen.