Effects of fuel moisture content on pollutant emissions from a rocket-elbow cookstove
Date
2018
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Abstract
Cookstoves have been studied in recent decades for their health- and environment-relevant emissions. Many pollutants, stoves, and burning parameters have been investigated across these studies, including fuel moisture content, which is believed to have substantial impact on stove emissions. Yet, the effects of fuel moisture content on emissions remain poorly characterized. To address this gap in knowledge, this study characterized particle and gas-phase pollutant emissions during a laboratory experiment exploring three levels of fuel moisture from a single tree sample. Moisture levels tested here varied from 5% to 30% water content, by weight. A novel technique for re-moisturizing the fuel samples was developed and employed to expedite the experimental duration and to ensure consistency across tests. Results from the study demonstrate strong trends in emissions related to changes in moisture content. Results also suggest there are benefits to drying wood to below 10% moisture content as compared to burning wood that is slightly above the 20% level recommended by the U.S. Environmental Protection Agency. When wood was dried to 5% instead of 25%, modified combustion efficiency improved and average mass-based emissions factors decreased for all pollutant species (formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, m+p-xylenes, o-xylenes, PM2.5, methane, carbon monoxide, and organic carbon) save black carbon. Dry fuel generated less smoke and higher temperatures than wet fuel. Wet fuel was also difficult to keep lit and burned much slower than dry fuel. Efficiency, burn rate, and stove temperature all affect the way people use their stoves for heating or cooking. Since moisture content impacted efficiency, burn rate, and temperature during this study, as well as multiple gas and particle-phase pollutants, moisture content should be accounted for in future stoves studies, both in the lab and in the field.
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Subject
emission
moisture
cookstove
pollutant
fuel