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

Abstract

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 (PM 2.5 ), 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 PM 2.5 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.

Supply Considerations for Scaling Up Clean Cooking Fuels for Household Energy in Low‐ and Middle‐Income Countries

“…Examples of these low emission stoves include the Mimi Moto pellet stove and a small number of other options which have shown promise under laboratory and recent field testing (Champion & Grieshop, 2019). Examples of these low emission stoves include the Mimi Moto pellet stove and a small number of other options which have shown promise under laboratory and recent field testing (Champion & Grieshop, 2019).…”

“…Compressed biomass fuels are capable of clean combustion (i.e., low pollutant emissions) when manufactured to high standards and used as intended in stoves designed to meet Tier 4 or better performance targets for emissions and efficiency (Champion & Grieshop, 2019). Compressed biomass fuels are capable of clean combustion (i.e., low pollutant emissions) when manufactured to high standards and used as intended in stoves designed to meet Tier 4 or better performance targets for emissions and efficiency (Champion & Grieshop, 2019).…”

“…These rules and standards that cover both the stove and the fuel are critically important given the differences in performance that have been seen between laboratory studies and field measurements (Champion & Grieshop, 2019;Wathore et al, 2017). African national standards organizations (e.g., Rwanda Bureau of Standards, Malawi Bureau of Standards) are beginning to use ISO guidance in the regulation of improved cookstoves.…”

“…Biomass pellets and other forms of compressed biomass are included in the list of clean household fuels because they have the potential to be burned cleanly in highly performing advanced stoves (sometimes termed Tier 4 stoves in the early development of cookstove standards). Examples of these low emission stoves include the Mimi Moto pellet stove and a small number of other options which have shown promise under laboratory and recent field testing (Champion & Grieshop, 2019). Other forms of biomass such as charcoal are classified as polluting fuels and are not incorporated in this analysis.…”

“…Biomass compression, when carried out to produce a consistent product, can reproducibly form a solid biofuel that has low moisture content and high energy density. Compressed biomass fuels are capable of clean combustion (i.e., low pollutant emissions) when manufactured to high standards and used as intended in stoves designed to meet Tier 4 or better performance targets for emissions and efficiency (Champion & Grieshop, 2019). Depending on the size and shape of compressed biomass, it may be called pellets or briquettes, with the latter being the larger of the two.…”