Optimization of herbaceous feedstock delivery to a network of supply depots for a biorefinery in the Piedmont, USA

Abstract

The southeastern USA has the potential to be a significant producer of bio-based products; however, research is still needed to demonstrate the most cost-effective feedstock delivery system for this region. A logistic system that has shown promise is one utilizing a network of supply depots. This study calculated the cost to produce a stream of size-reduced herbaceous biomass (i.e., switchgrass) for five theoretical depots in the Piedmont province. Three depots were located in south central Virginia and two in north central North Carolina. A logistics system with a 20-bale handling unit was used for load-out operations at 199 theoretical satellite storage locations (SSLs) within a 48 km radius of each depot location. The distribution of potential production fields and the transportation distance from SSLs to the depots were determined with spatial and network analyses. Based on an analysis of potential land cover available for feedstock production, the annual capacity per depot ranged from 80 839 to 170 830 Mg, resulting in a total annual capacity of 555 195 Mg for all five depots. Cost to deliver feedstock for 24/7 operation, 48 weeks per year ranged from 46.03 to 62.86 USD Mg−1 annual capacity. At the low end, these costs were: SSL operation (22%), truck (29%), receiving facility (26%), and debaling-size-reduction (23%). The principle economy-of-scale factors were the receiving facility and debaling-size-reduction costs. To minimize per-Mg cost, depot capacity should be chosen such that equipment can be operated as close to 80% of design capacity as possible.