One of the Zambian projects of the Stockholm Environment Institute (SEI) aims at improving local knowledge of stove emissions and the country's capabilities to test smoke emissions. A laboratory at the National Council for Scientific Research (NCSR) has been provided with monitoring equipment, and two researchers, Dr Julius Kaoma and Dr George Kasali, who have been trained in stove testing. A number of different stoves and fuels relevant for Zambian conditions have been tested, both with regard to thermal efficiency and to emission of pollutants. The stoves tested have been the traditional stove, the Mbaula, a ceramic stove developed by NCAR, a metal stove for coal (mineral coal) proposed by Maamba Collieries Ltd. and an improved charcoal stove.

Only the traditional and the improved charcoal stoves are already on the market. The fuels tested were charcoal, coal briquettes and mineral coal. So far, only charcoal is widely used as a cooking fuel in Zambia, but there are forces at work to introduce both coal briquettes and raw coal on the household market. This makes emission testing all the more important. Results from tests of the traditional mbaula and ceramic stove using charcoal and coal briquettes were reported at a workshop in Siavonga, Zambia, in May 1993.

Since traditional stoves do not have chimneys and flues, the tests are being carried out in a simulated kitchen where pollution monitoring can be done without changing the operating conditions for the stove. When testing fuels that cause the greatest amount of pollution. such as raw coal, the researchers were forced to stop some of the tests to avoid being asphyxiated. Thermal efficiency tests are not yet being done in the form of meal-cooking tests, but only as water boiling tests. Thus the efficiencies recorded may not represent the results obtained when the stove is in normal use but they can provide some comparison between the different stoves tested.

The results of the tests indicate that the improved mbaula is slightly less efficient than the traditional type, but emits less pollution. The average thermal efficiency of the improved mbaula with the air inlet fully open was 25 per cent (which is relatively good), while the traditional mbaula had an average of 29 per cent at similar burn rates (0.21-0.23kg of charcoal per hour ie. roughly 1.6-1.7kW power output). Carbon monoxide (CO) emissions were lower from the improved mbaula (340g/kg charcoal) than from the traditional one (600g/kg). When the air inlet was in the 'saving mode', emissions increased with the improved mbaula. Thus, it appears that a choice has to be made between saving fuel and pollution emissions. The traditional mbaula achieves slightly better efficiency (thus reducing fuel consumption) than the improved mbaula, but results in higher pollution.

The project will also test CO concentrations in homes where charcoal is used for night heating during the cold season. This hazard is well known and although people are killed every year by CO poisoning, no actual measurements are known to have been made that could help estimate the risks. The project will focus attention on the exposure of people sleeping close to the stove. Results are expected in late 1994. The results may allow the project to make recommendations regarding the use of charcoal stoves for home heating in the cold season.

Last edited by Miriam Hansen .
Page last modified on Monday October 4, 2010 15:39:58 GMT.
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