Evaluation of Pre-processing and Storage Options in Biomass Supply Logistics: A Case Study in East Tennessee

Biofuels have been widely recognized as a potential renewable energy source that can lessen the United States’ dependence on imported petroleum and enhance the domestic economy. Particularly, biofuels derived from lignocellulosic biomass (LCB) have been the focus in the development of a sustainable biofuels industry. However, technical barriers in the LCB feedstock supply chain have been one of the major challenges impeding the economic viability of this industry. To expedite the commercialization process of LCB-based biofuels production, this paper employed a spatial mixed-integer mathematical model to explore the optimal biomass logistic system for a switchgrass-based biofuels biorefinery in East Tennessee.

The evaluated logistic systems in this study included five conventional systems (one round bale system, one square bale system, and three mixed bale systems) in the baseline scenario and one stretch-wrap bale system in the preprocessing scenario. Results showed that the stretch-wrap bale system could potentially reduce total logistic cost of switchgrass by 12 to 21% compared that of the conventional systems. Also, the result of the optimal case in the conventional systems suggested that the mixed bale system without storage protection is most economical after taking into account the dry matter loss during storage.

This study also provided information regarding the optimal location of a biorefinery, a switchgrass production plan, monthly harvested and delivered tonnage, and the draw area of switchgrass under each logistic system. The optimal location of a commercial-scale biorefinery was identified to be located in the northwest of Monroe County, a location close to the demonstration plant in Venore, Tennessee. Additionally, this study showed that the percentage of available hay land used for switchgrass production, the switchgrass-ethanol conversion rate, the energy prices, and the storage dry matter loss of compact switchgrass bale produce significant impacts on the total logistic cost of switchgrass for the biorefinery.