Pellet-Fed Gasifier Stoves Approach Gas-Stove Like Performance during in-Home Use in Rwanda.

Nearly all households in Rwanda burn solid fuels for cooking. A private firm in Rwanda is distributing forced-draft pellet-fed semigasifier cookstoves and fuel pellets. We measured in-use emissions of pollutants including fine particulate matter (PM2.5), organic and elemental carbon (OC, EC), black carbon (BC), and carbon monoxide (CO) in 91 uncontrolled cooking tests (UCTs) of both pellet and baseline (wood; charcoal) stoves. We observed >90% reductions in most pollutant emission factors/rates from pellet stoves compared to baseline stoves. Pellet stoves performed far better than gasifier stoves burning unprocessed wood, and consistent with ISO tiers 4 and 5 for PM2.5 and CO, respectively. Pellet stoves were generally clean, but performance varied; emissions from the dirtiest pellet tests matched those from the cleanest traditional stove tests. Our real-time data suggest that events occurring during ignition and the end of testing (e.g., refueling, char burnout) drive high emissions during pellet tests. We use our data to estimate potential health and climate cobenefits from stove adoption. This analysis suggests that pellet stoves have the potential to provide health benefits far above previously tested biomass stoves and approaching modern fuel stoves (e.g., LPG). Net climate impacts of pellet stoves range from similar to LPG to negligible, depending on biomass source and upstream emissions.