Biofuel is one candidate that can address the global warming and energy security challenges faced by the transportation sector. However, biofuel production is subject to unpredictable external disturbances caused by demand variation, regional instability and extreme weather. It is highly desired to design a biofuel plant such that it has operational flexibility to survive through these disturbances. Gasification based thermo-chemical conversion is one of the promising approaches: the plant can produce a variety of products including electricity, liquefied petroleum gas, gasoline, and diesel while taking almost any kind of biomass as feedstock. In this paper, technical and economic performance of thermo-chemical biofuel plants is evaluated under external disturbances, including extreme weather, market fluctuation, and policy uncertainties. Four plant configurations with varying electricity generation capacity and different in-plant hydrogen production methods (methane autothermal reforming or water-gas shifting) are considered. It has been found that by providing additional electricity production capacity and producing hydrogen via methane reforming, the biofuel plant could have the best chance to maximize profit under external disturbances. Results from this research are expected to help relevant biofuel stakeholders, i.e. investors, plant managers, and government agencies, to make key decisions with regards to investment, plant operation, as well as policy. (C) 2011 Elsevier Ltd. All rights reserved.