Comparison between two policy strategies for scheduling trucks in a biomass logistic system

Approximately 75% of the cost to load, haul, and deliver a weekly supply of herbaceous biomass from temporary storage locations near the production fields to a bioprocessing plant (50Mg/h average capacity, 24/7 operation) is truck cost. The management policy that a bioprocessing plant uses to schedule trucks determines the maximum number of trucks required, and thereby, the total cost for the logistic system. Three land use rates corresponding to 50%, 45%, and 40% of existing pastureland within a 3.2-km radius of chosen satellite storage locations were used to establish a production base surrounding the plant location. Total area harvested was 25,500 ha, or about 2.1% of the total land area in the 7-county region studied. Assumed average yield was 8.3Mg/ha. Two different management policies, one based on travel time (Policy 1) and another based on the assignment of trucks to given sectors of the surrounding production base (Policy 2) were used to develop truck schedules. The logistic system was modeled as a discrete event simulation model, and the schedule was validated. The maximum number of trucks needed for the logistic system was 32, 33 and 34 for 50%, 45% and 40% land use rates, respectively. In Policy 1, the maximum number of loads accumulated in the at-plant inventory was 384 truckloads at 50% land use rate (maximum inventory corresponds to about 3 days of plant operation). In Policy 2, the maximum number of loads accumulated in the at-plant inventory was 330 truckloads at 50% land use rate. Total number of loader and unloader operating hours for both the policies was computed, and the loader and unloader utilization rates were 83.5% and 70.8%, respectively. The delivered cost (load, haul, and unload) varied from USD14.68 (Policy 1) to USD16.14 per Mg (Policy 2) for 15% w.b. moisture content biomass.