A multiobjective optimization model integrating with high-resolution geographical data was applied to examine the optimal switchgrass supply system in Tennessee that considers both feedstock cost and greenhouse gas (GHG) emissions in the system. Results suggest that the type of land converted into switchgrass production is crucial to both plant gate cost and GHG emissions of feedstock. In addition, a tradeoff relationship between cost and GHG emissions for the switchgrass supply is primarily driven by the type of land converted. The imputed cost of lowering GHG emissions in the feedstock supply system was also calculated based on the derived tradeoff curve.