AN INVENTORY CONTROL MODEL FOR SUPPLYING BIOMASS TO A PROCESSING FACILITY

An inventory control model was developed to determine the least cost a pproach for supplying biomass to a processing plant. Model application s were made for the plantation, harvest, and manufacturing components of woody biomass to ethanol supply systems to assess efficiency and fi nancial performance. Model solutions determined the optimum inventory policy for hybrid poplar plantations grown over rotation lengths of 4 through 8 yr. The harvest occurred during a 6-mo time frame after the growing season. All biomass was directed to an ethanol manufacturing f acility capable of processing 10,000 Mg(OD) of harvested raw materials /mo-1. At this level, the facility was required to meet an output dema nd of just over 3,000,000 L/mo-1. An evaluation of model solutions led to an optimum biomass rotation length of six yr and an ethanol produc tion cost of $0.376 L-1. The least-cost policy established the harvest ing requirements and storage schedules for standing trees, harvested r aw materials, and ethanol. Inventory control had a major impact on pro duction costs, with alternate strategies within the rotation increasin g ethanol costs by as much as 62%. ff biomass is to compete as a viabl e feedstock for alternative fuel or chemical production, additional co st reductions will be necessary. These can be realized through the inv entory control of standing trees, harvested materials, and final produ ct.