Harvest schedule to fill storage for year-round delivery of grasses to biorefinery

Number of annual harvest days is a critical variable in the scheduling of year-round delivery of grasses to a biorefinery. It defines the number of harvest machines required and the size of satellite storage capacity. An increase in both these parameters increases capital cost and thus the average delivered cost of biomass for year-round operation. The objective of this study was to determine the impact (number of harvest machines required and storage capacity required) of several harvest scenarios for switchgrass (Panicum virgatum). Calculations were done for a database of potential production fields within a 48-km radius of Gretna, Virginia. Four harvest scenarios were chosen ranging from short, October–December to extended, July–March. The extended harvest required only 33 round balers while the short (October–December) harvest required 64; consequently, capital cost for extended-harvest balers was only 51% of the baler capital cost for the short season. Maximum required storage capacity was 75% of the total annual harvest for the short season and 44% for the extended season. Capital cost to build storage was reduced by 41% by selecting the extended harvest season.