The objective of this study was to simulate biomass co-firing in a dry-fed, entrained-flow gasifier in an integrated gasification combined cycle (IGCC) power plant and examine the resulting performance, environmental response, and economic response. To develop a more complete understanding of the impact of co-feeding biomass, each case was examined using a limited life cycle greenhouse gas (GHG) analysis, which examines GHG emissions beyond the plant stack. Included in the limited life cycle GHG analysis were anthropogenic greenhouse gas emissions from the production, processing, transportation, and fertilization of biomass and from mining, transporting and handling coal.