Efficiency and emissions of charcoal use in the improved Mbaula cookstove

An improved chamber method was used to evaluate the thermal performance and emission characteristics of charcoal in an unvented cookstove known as the Improved Mbaula. Emission factors and rates for pollutants, burn rate and stove efficiency were determined. The pollutants that were continuously monitored were carbon monoxide (CO), sulphur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), and respirable suspended particulates (RSP). Concentrations of CO, nitrogen oxides and RSP in the test chamber (a simulated kitchen) reached levels in excess of guidelines recommended in industrialized countries. Concentrations of SO2 did not exceed known levels. If the test chamber actually is a good simulation of a common kitchen, the levels reached warrant concern for the health of people exposed, mostly women and children. Levels of pollution in actual kitchens will be assessed in a later study. The adjustable opening of the stove proved effective in regulating the burn rate. At half air input, burn rate decreased by about 40%, while emissions increased by about 60% compared to operation at full air input. Emissions of CO were 340 g/kg charcoal at full air input, which was taken to be the normal mode of operation. The average thermal efficiency (PHU) of the improved mbaula was 25% compared to 29% for the traditional charcoal stove. 16 refs, 4 figs, 12 tabs