The amount of available biomass feedstock and associated cost components were analyzed to determine the potential increase in energy capacity of two existing combined heat and power plants in Mississippi. The amount of corn stover and forest logging residue within a 10-mile radius can satisfy the existing requirements of CHP plants in Scott (1 MW) and Washington counties (5 MW). Transporting feedstock within a smaller source area had lower transportation costs, but higher total unit cost than the two other source buffer scenarios. However, capital costs associated with higher plant capacities were significantly higher and plant expansion may not be economically advantageous. Increasing the CHP capacity from 1 MW to 2 MW in Scott county and 5 MW to 10 MW in Washington county might be a sustainable approach by drawing feedstock from a smaller area and at lower utilization rates, while keeping transportation costs low.