ANALYSIS OF LOGGING RESIDUES FOR BIOENERGY INCLUDING QUALITY-RELATED ISSUES

Abstract

Woody residues, a waste product of the logging industry, are a reliable source of bioenergy. Tree limbs can either be immediately collected for chipping after a whole-tree (WT) harvest operation or be left on the forest floor to dry after a cut-to-length (CTL) harvest operation. In both cases, residues can be collected and transported to a biorefinery. Biomass industries, which convert woody matter to ethanol, can stimulate local economic growth and encourage energy independence. However, logistical uncertainties about residue retrieval stunt industrial growth. To help overcome these uncertainties, two different collection methods are modeled to determine cost efficiencies. The CTL process considers gathering woody biomass on the forest floor both with and without a bundler, retrieval by a forwarder, chipping at the landing, and loading into a dry van truck. The WT process model considers delimbing trees at a landing, feeding the limbs through a grinder and filtering screen, and loading the material into a truck. Each method presents trade-offs. CTL harvesting allows for less ash and lower moisture content in the biomass, which translates to lower mechanical drying cost. By contrast, WT harvesting reduces operational costs because equipment and manpower are already located at the landing. To further investigate the Cost of Poor Quality (COQ) associated with moisture management, a transportation sensitivity analysis is conducted to determine the effect of payload weight on truck highway efficiency. All parameters are then summed to determine the most economic feasibility of each method.