AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Carbonaceous Semivolatile Organic Matter Emitted from a Pellet-fired Biomass Boiler
MICHAEL HAYS, John Kinsey, Ingrid George, William Preston, Carl Singer, Bakul Patel, U.S. EPA
Abstract Number: 450 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract Biomass pellets are an intriguing source of renewable energy; although, the air pollution and exposure risks posed by the emissions from burning pellets in biomass boilers are uncertain. The present study examines the carbon composition of fine particle matter (PM) emissions from a biomass boiler (OBB) firing switch grass and hardwood biomass pellets at different test cycles. The organic and elemental carbon (OC and EC) content and select semivolatile organic compounds (SVOCs) in filter-collected PM were identified and quantified using thermal-optical analysis and gas chromatography-mass spectrometry (GC-MS), respectively. Fine PM emissions from the OBB ranged from 0.4 g/kg to 2.91 g/kg of pellets burned of which 40% ± 17% w/w was carbon. The sum of GC-MS quantified SVOCs in the PM emissions varied from 0.13 g/g OC to 0.41 g/g OC. Relatively high levels of oxygenated compounds were observed in the PM emissions, and the most predominant individual SVOC constituent was levoglucosan (12.5 mg/g OC - 320 mg/g OC). The effect of boiler test cycle on emissions was generally greater than the effect due to pellet fuel type. Organic matter emissions increased at lower loads owing to less than optimal combustion performance. Compared with other types of residential wood combustion, pellet burning in the OBB lowered PM emissions by nearly an order of magnitude. The PM emitted from burning pellets in boilers also contains comparatively less carbon; however, the toxic polycyclic aromatic hydrocarbons (PAH) in the PM from pellet-burning varied substantially, and produced 2-10 times more benzo[k]fluoranthene, dibenz[a,h]anthracene, and indeno[1,2,3-c,d]pyrene. These results suggest that further toxicological evaluation of biomass pellet burning emissions is required to properly understand the risks posed.