Emissions and emission factors for Dichrostachys cinerea, Morus Lactea, Piliostigma thonningii, Combretum molle, and Albizia grandibracteata firewood species and their charcoals

Firewood and charcoal are the most dominant sources of fuel for domestic cooking applications in sub-Saharan Africa. In this study, performance and emission characteristics of firewood and charcoal from five commonly used species, namely, Dichrostachys cinerea, Morus Lactea, Piliostigma thonningii, Combretum molle, and Albizia grandibracteata were obtained. The water boiling test and emissions monitoring system for CO, CO, and PM were used to determine fuel and energy consumption, thermal efficiency and emissions, and emissions’ factors. The results showed that firewood combustion required higher energy consumption compared to charcoal combustion. High-power thermal efficiency was the highest (> 45%) for all charcoal derived from the firewood species. During hot-start, cold-start, and simmering operations, it was observed that thermal efficiencies were generally higher for charcoal fuels (≥ 80%) compared to the firewood (< 40%) from where they were pyrolyzed. Firewood has a much lower indoor CO emissions footprint when compared to using charcoal. Nonetheless, CO emission levels for both firewood and charcoal exceed the Environmental Protection Agency (EPA) guidelines of 35 ppm (1-h average). CO emission factors are the most dominant and highest contributors to greenhouse gas emissions from household use of firewood and charcoal. Overall, this work re-affirms the need for proper ventilation when firewood and charcoal are used in combustion.