AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Constituents of Health Concern from Biomethane Cooking Stove Combustion Exhaust
CHAO WAN, Yin Li, Chris Alaimo, Jian Xue, Minji Kim, Norman Kado, Peter Green, Thomas Young, Ruihong Zhang, Michael Kleeman, University of California, Davis
Abstract Number: 815 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract Biogas is a promising source of renewable energy with composition similar to natural gas. Advances in anaerobic digestion methods and biogas purification technology will soon produce upgraded biogas (=biomethane) that can be used in any application where natural gas is used, including in residential cooking stoves where the potential for exposure to direct combustion exhaust is very high. Here we report the composition of biogas and biomethane including ammonia, extended hydrocarbon, sulfur, mercury, metals, bacteria, volatile and semi-volatile organic compounds from seven different biogas production streams. Among all the constituents, halocarbons and siloxanes were identified as contaminants of concern due to their potentially high concentrations and toxic combustion products. A series of controlled combustion experiments were conducted with a residential cooking stove using biomethane spiked with dichloromethane and 1,2-dichloro-1,1-difluoroethane to calculate the conversion rates of chlorine and fluorine becoming hydrochloric acid and hydrofluoric acid. D4 and D5 siloxanes were spiked into the fuel to study the formation and size distribution of silica nanoparticles. Our experiments show that all siloxanes are combusted to silica particles but the size distributions vary significantly depending on siloxane concentrations. A coagulation model is developed to describe this process. Pipeline standards are proposed for halocarbons and siloxanes based the experimental results.