Feedstock Dependence of Emissions from a Reverse-Downdraft Gasifier Cookstove

Abstract The present study investigates the combustion process of the producer gas from a gasifier cookstove, for four solid biomass fuels: wood pellets (WP), wheat straw (WS), sheep manure (SM) and cow manure (CM). It was found that more primary air and/or a deeper fuel bed reduces tars in the producer gas and increases the combustion efficiency, especially from low-ash-containing WP. At higher air supply rates, indications of a strong influence from the fuel ash content on the emissions were found. Although more combustible gases and fewer tars are produced in the conversion process, a substantial increase in particulate matter (PM) emissions is noted. At low air supply rates, the emissions of particulates with an aerodynamic diameter ≤2.5 μm (PM2.5) released from the combustion process are in the range of 6–30 mg⋅MJreleased−1 (WP