10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
In-field Emission Measurements of Forced-draft Pellet and Traditional Wood and Charcoal Stoves in Rwanda
WYATT CHAMPION, Andrew Grieshop, North Carolina State University
Abstract Number: 1668 Working Group: Indoor Aerosols
Abstract Nearly three billion people rely on solid fuel burning stoves that emit particulate and gaseous pollutants causing adverse health and climate effects. In Rwanda, 96% of all homes utilize solid fuels for cooking, and wood is the primary cooking fuel in nearly all rural homes (GACC, 2012). Household air pollution (HAP) is the fourth highest risk factor for morbidity and mortality in Rwanda, and respiratory infection is the leading cause of life lost.
The current study assesses the Mimi Moto forced-draft pellet-fed semi-gasifier cookstove in urban and rural homes in Gisenyi, Rwanda. The objective of the study is to compare emissions of the Mimi Moto to traditional wood (three stove fire) and charcoal (coalpot/Jiko) stoves. The Mimi Moto is distributed through a unique business model that promotes availability and affordability, and provides the stove, delivery, training, and repair at no cost.
Uncontrolled cooking tests (UCTs) were conducted in 22 homes (2 tests per home) during November and December of 2017. A follow-up deployment of equal size is scheduled for May 2018, for a total UCT sample size of approximately 90. The UCT has the advantage over other test types (e.g., Water Boiling Test, Controlled Cooking Test) of being relatively unobtrusive and likely more representative of actual cooking practices. The Stove Emission Measurement System (STEMS) was deployed and measured real-time concentrations of carbon dioxide (CO2), carbon monoxide (CO), PM2.5 light scattering and absorption, and integrated filter PM2.5 mass and organic/elemental carbon (OC/EC). Filter analyses are on-going, and additional analyses will include real-time emissions data (MCE, SSA), and particle optical properties (Bap, Bsp) with a comparison against filter measurements. Field UCT results will be compared against field WBT results sampled using the same equipment.
Preliminary results found the Mimi Moto to have a 5- and 16-fold lower median CO emission factor (EF, g/kg) compared to the wood and charcoal stoves, respectively. Compared to previous field cookstove emissions studies (Roden et al., 2006; Grieshop et al., 2011; Wathore et al., 2017), median CO EFs were around 10-20% and 30% lower for wood and charcoal, consistent with inter-test variability for these traditional fuels. The Mimi Moto CO EF (20 g/kg) was higher than previously reported laboratory test results (conducted by a different group), highlighting the common observation that field tests may represent more realistic and “dirty” events compared to laboratory test results. The Mimi Moto stove also had on average 8- and 3-fold lower median test-average PM2.5 light scattering compared to the wood and charcoal stoves. The distributions of Mimi Moto CO and PM2.5 light scattering data were asymmetrical, clustered around a low mean value with a long upwards tail, suggesting that potential low emissions are not always realized in the field. This finding underscores the importance of proper stove usage. Properly functioning Mimi Moto stoves were clean-burning. However poorly operated Mimi Moto stoves were, for at least PM2.5 light scattering, as dirty as their well-operated traditional counterparts. This study gives field evidence that forced-draft pellet-fed gasifier cookstoves have great potential to reduce emissions (and exposures), but may be highly sensitive to operational conditions.
References: [1] Global Alliance for Clean Cookstoves. Global Alliance for Clean Cookstoves: Rwanda Market Assessment; 2012. [2] Grieshop, A. P., et al. Health and Climate Benefits of Cookstove Replacement Options. Energy Policy 2011, 39 (12). [3] Roden, C. A., et al. Emission Factors and Real-Time Optical Properties of Particles Emitted from Traditional Wood Burning Cookstoves. Environ. Sci. Technol. 2006, 40 (21). [4] Wathore, R., et al. In-Use Emissions and Estimated Impacts of Traditional, Natural- and Forced-Draft Cookstoves in Rural Malawi. Environ. Sci. Technol. 2017, 51 (3).