A biomass logistics system using large packages of sufficient size and density to maximize legal highway loads and rapid load/unload times was expected to minimize feedstock costs. Such a system has been field tested conceptually at Texas A&M University, but modeling was used to predict system performance prior to design of prototypes. Integrated Biomass Supply and Logistics (IBSAL), logistics system simulation software developed by the U.S. Department of Energy, was employed to build a simulation model of the conceptual system. The new machine concepts required development of new IBSAL elements to model machine functions. Through a sensitivity analysis, the significance of several factors associated with the design and performance of the conceptual machines was evaluated. The estimated logistics cost ranges from 19.65 $ Mg-1 to $41.26 $ Mg-1. The dry matter density of biomass modules, the operating efficiency of the forage harvester, and the travel speed of the module hauler proved to be the most influential factors for the system performance, and provide insights into design requirements. (C) 2012 Elsevier Ltd. All rights reserved.