Biorefi neries are seen as a key component for the transition toward a resource-effi cient, lowcarbon bio-economy. The green biorefi nery (GBR) concept is promoted in several countries to create business and employment opportunities in rural areas. It aims at providing alternative utilization pathways for surplus grassland areas by producing bioenergy, biomaterials, livestock feed, and organic acids. We have developed a spatially explicit, mixed integer programming model that maximizes total producer surpluses of GBR supply chains subject to resource endowments by selecting optimal plant locations and sizes. The model is applied to assess the economic viability of three GBR concepts compared to biogas plants. Impacts of uncertain model input parameters on model outputs are analyzed by Monte-Carlo simulations and regression analysis. The model results reveal that green biorefi neries could utilize signifi cantly more biomass than biogas plants, leading to higher regional feedstock prices. Furthermore, the Monte-Carlo simulation results demonstrate that the economic viability of green biorefi neries mainly depends on the selected process layout and the prices of the main products. Under favorable market conditions GBRs are economically viable even without policy support measures with average profi ts between €15 and €115 t -1 feedstock input.