Fuel efficiency and air pollutant concentrations of wood-burning improved cookstoves in Malawi: Implications for scaling-up cookstove programs

Developing countries are grappling with how to reduce household air pollution (HAP) from cooking with solid fuels and the traditional three stone fire (TSF). Laboratory studies have shown that improved cookstoves may offer reductions in fuel use, emissions of carbon monoxide (CO) and fine particulate matter (PM2.5), yet there is limited evidence from “real-world” settings showing how improved stoves perform compared to the traditional TSF. Our study takes place in a semi-controlled setting in Malawi and was designed to quantify fuel efficiency improvements and air pollutant concentration reductions capabilities of two improved cookstoves. We perform a Water Boiling Test to compare the TSF with the locally produced clay stove known as the Chitetezo Mbaula (CM) and the Philips gasifying stove. We find that the CM uses 53% of the fuel used by the traditional TSF, and produces 59% of CO, and 50% of PM2.5 of the TSF. The Philips stove uses 31% of the fuel, and produces 38% of CO, and 22% of PM2.5 of the TSF. We consider the potential for the wide-scale adoption of these technologies given their relative costs and conclude that lower-cost, intermediate quality cookstoves are an important and realistic first step toward reducing HAP.