Effect of In-woods Storage of Unprocessed Logging Residue on Biomass Feedstock Quality

Abstract. To avoid material decomposition and reduce the high cost of conventional drying and storage methods, an air-drying process was designed. This process involved no chipping of biomass at the harvest site and was tested at two study sites in Escanaba, Upper Peninsula, Michigan, from June to November in 2011. The key objective of this study was to investigate the impact of air-drying on biomass moisture content (MC) and higher heating value (HHV) over field storage. In the mean time, the effect of different positions within a pile, biomass pile sizes, and weather conditions on biomass moisture change was also tested. Results indicated that biomass MCs at different positions within a pile were statistically uniform and were significantly lowered during the field storage period. In addition, results suggested that smaller pile is a better way to store woody biomass for short-term use, while larger pile can be a more appropriate option for long-term storage. During the 5-month storage period, biomass HHVs maintained stable. Overall, we concluded that field piling of un-processed biomass is a reliable storage method for a year-round biomass supply with no additional costs. Regression analysis also showed that air humidity could significantly affect field-stored biomass MC, while the air temperature and cumulative precipitation turned out to have unnoticeable effect on biomass MC.