Evaluating the Laboratory Performance of Pellet-Fueled Semigasifier Cookstoves

This study examines three representative semigasifier cookstove models each burning four types of pelletized-biomass fuel (hardwood, peanut hull, rice husk, and wheat straw) using the International Organization for Standardization (ISO) 19867-1:2018 protocol. ISO tier ratings for fine particulate matter (PM_2.5) and carbon monoxide (CO) emissions ranged 1-4 and 2-5 (where 5 = cleanest), respectively, suggesting that pellet-fueled cookstoves may provide substantial emissions reductions, dependent upon stove/fuel matching and operation, over other biomass-fueled cooking alternatives. PM_2.5 emission factors based on useful energy delivered (EF_d) varied by up to 25-fold, and organic and elemental carbon (OC and EC) EF_d values respectively varied by >200- and ∼100-fold, reflecting complex variability in PM_2.5 composition. These semigasifier cookstoves showed higher ultrafine particle (UFP) emissions but lower bulk PM_2.5 emissions. Operation of pellet-fueled cookstoves at higher firepower resulted in higher PM_2.5 and UFP emission factors and higher EC-to-total-carbon ratios; operation at lower firepower resulted in higher gaseous pollutant emission factors. Results of this work provide technical guidance for stove developers, users, and policy-makers. These ISO-protocol-based emission factors are also pertinent to health and climate modeling efforts.