In-Field Emissions from Pellet-Fed Gasifier Stoves in Urban Zambia
Stephanie Parsons, ANDREW GRIESHOP, North Carolina State University
Abstract Number: 496
Working Group: Combustion
Abstract
In Zambia, 76% of the urban population still relies on charcoal for cooking. A private stove distribution company in Zambia is co-developing (with a Swedish engineering company) a forced-draft, pellet-fed gasifier stove, the SupaMoto, an ultra-low-emission biomass stove to minimize health and climate impacts of cooking. To evaluate real-world emission performance, we conducted 48 uncontrolled cooking tests of SupaMoto prototypes and traditional charcoal stoves, measuring carbon monoxide (CO), black carbon (BC), real-time particle light scattering, fine particulate matter (PM2.5), elemental carbon (EC), and organic carbon (OC). The prototype SupaMotos were tested by cooks who typically use a similar, commercially available pellet gasifier stove. CO emission factors (EFs) of SupaMoto stoves (4.7 g kg-1) were on average 98% lower than those of charcoal stoves (226 g kg-1), consistent with the “best” tier (Tier 5 in the laboratory-based ISO targets) of cookstove emissions. Mean PM EFs for SupaMoto (1.0 g kg-1) were 43% lower than charcoal stoves (1.8 g kg-1). EC EFs from SupaMoto stoves (0.35 g kg-1) were higher than those of charcoal stoves (0.21 g kg-1); however, real-time data show that most BC emissions occurred during startup, and SupaMoto tests ignited with kindling had BC EFs 2.5 times higher than those ignited with kerosene. Poor startup performance and misapplication of a ‘top plate’ diffuser during tests was also associated with high PM emission events and elevated EFs. Analysis of various stove use metrics collected by the stove vendor (e.g., pellet purchases, time since stove purchase, hours of stove use measured by on-board sensors) indicated a weak to moderate anticorrelation between level of user experience and test EFs, suggesting user experience is a determinant of emissions. Finally, we conduct analysis suggesting that substantial net climate benefits would result from the widespread adoption of the SupaMoto.