Effect of outdoor storage losses on feedstock inventory management and plant-gate cost for a switchgrass conversion facility in East Tennessee

• We model switchgrass inventory management for an ethanol facility.
• Last in, first out inventory management during storage minimized plant-gate cost.
• Dry matter loss increasing at a decreasing rate with time in storage was key factor.
• Coordination of timing and location of harvest with storage and delivery is implied.

Little is known about the potential impacts of storage losses on the optimal design of a switchgrass (Panicum virgatum) supply chain for an ethanol conversion facility. This study analyzed how storage losses impact plant-gate cost and feedstock inventory management for a 94,635 kL year−1 switchgrass-based ethanol conversion facility in East Tennessee. A spatially-oriented, mixed-integer mathematical programming model was used to analyze plant-gate cost and harvest, storage, and delivery schedule for switchgrass packaged in large round or rectangular bales. Results indicate that last in, first out inventory management of feedstock minimized plant-gate cost. The key factor influencing inventory management was dry matter loss increasing at a decreasing rate with time in storage and distance of switchgrass production from the conversion facility. Our findings imply that the conversion facility can optimize the feedstock inventory and delivery management through coordinating the timing and location of switchgrass harvest with storage and delivery.