Comparison of five rural, wood-burning cooking devices: Efficiencies and emissions

The following cooking devices were compared: an open fire built on the ground, an “improved” open fire built on a raised grate, a one-pot metal stove, a two-pot ceramic stove and a two-pot metal stove. Efficiencies (ratios of energy entering the pot to the energy content of the fuel consumed) were determined by carrying out a computer-controlled version of the standard Water Boiling Test. Emission concentrations of smoke, carbon monoxide and sulphur dioxide were measured by means of a fume extraction hood, an optical smoke-density meter and an electrochemical flue-gas analyzer. Average emissions of smoke were lowest for the improved open fire and the two-pot ceramic stove, with the remaining devices higher emitting by factors from 1.5 to 3. Emissions of carbon monoxide and sulphur dioxide were lowest for the two open fires; the stoves were higher emitting by factors ranging from 2 to 3 for carbon monoxide and 3 to 10 for sulphur dioxide. Average efficiencies were 14% for the open fire, 21% for the improved open fire, and (with no statistically significant difference) 20 to 24% for the stoves.