Modeling Biomass Collection and Woods Processing Life-Cycle Analysis*

A deterministic spreadsheet model developed in an earlier Consortium for Research on Renewable Industrial Materials (CORRIM) project that calculates cost, fuel, and chemical outputs of forest management and harvesting activities was modified to include logic for systems used to recover forest residue. Two illustrative biomass recovery systems with variations were modeled. A system to recover residues after whole-tree harvesting operations was applied to a representative forest stand in the Inland West. Whole-tree chipping in an early thinning was applied to a representative forest stand in the Southeast United States. Emission factors and life-cycle outputs were developed for the systems through the SimaPro v7.3 model using one if its environmental impact methodologies called TRACI2. Most environmental outputs, including global warming potential, had a direct relationship to fuel consumption of the recovery systems. These outputs were subsequently used as inputs to life-cycle analysis in biofuel conversion facilities. Fuel consumption for recovery of residues from the log landing was 8.10, 12.0, and 16.0 liters per bone dry metric ton (BDmT) at haul distances of 48, 97, and 145 km, respectively. Corresponding fuel consumption for whole-tree chipping and hauling at these distances was 10.5, 16.0, and 21.5 liters/ BDmT. Shuttling ground residue from the landing for reload and a subsequent long haul of 145 km increased fuel consumption 32 percent over the residue recovery base case. Shuttling loose residue for centralized processing with a long haul distance of 145 km increases fuel consumption by 86 percent over recovery directly from the landing. The location, slope conditions, and ease of access of forest biomass supplied to biofuel plants are highly variable. Additional variability derives from the size and distribution of material in the forest stand. The combination of these variables will determine the economic feasibility of biomass recovery. Generalized data on biomass recovery operations are limited because marginal economics of those systems have limited the number of field operations that fully represent the range of conditions encountered in forest biomass recovery. A modeling approach was used in this project to estimate cost, fuel consumption, and environmental output for two types of biomass recovery: recovery of forest residues after logging and recovery of biomass from the early thinning of forest stands. The environmental outputs from the modeling efforts were then forwarded to subsequent stages of biomass processing. The subsequent stages were modeled as part of a larger Consortium for Research on Renewable Industrial Materials (CORRIM) biomass life-cycle project targeting forest biomass for use as a feedstock in facilities that convert the material to a biofuel or chemical product through thermoconversion or bioconversion. The deterministic spreadsheet model developed for the first two phases of the CORRIM life-cycle projects (Johnson et al. 2004, Oneil et al. 2010) was extended in this project to accommodate analysis of biomass recovery operations. The first two CORRIM life-cycle phases focused on various wood products, such as lumber and plywood from forest resources grown and harvested in specific regions of the country. The first phase included the Pacific Northwest and The authors are, respectively, Professor Emeritus, Univ. of Idaho, Moscow ([email protected] [corresponding author]); and Professor Emeritus and Research Scientist, College of the Environment, School of Environmental and Forest Sci., Univ. of Washington, Seattle ([email protected], [email protected]). This paper was received for publication in February 2012. Article no. 12-00019. * This article is part of a series of nine articles addressing many of the environmental performance and life-cycle issues related to the use of wood as a feedstock for bioenergy. The research reported in these articles was coordinated by the Consortium for Research on Renewable Industrial Materials (CORRIM; http://www.corrim.org). All nine articles are published in this issue of the Forest Products Journal (Vol. 62, No. 4). Forest Products Society 2012. Forest Prod. J. 62(4):258–272.