Possibilities for sustainable biorefineries based on agricultural residues – A case study of potential straw-based ethanol production in Sweden

This study presents a survey of the most important techno-economic factors for the implementation of biorefineries based on agricultural residues, in the form of straw, and biochemical conversion into ethanol and biogas, together with production of electricity and heat. The paper suggests locations where the necessary conditions can be met in Sweden. The requirements identified are regional availability of feedstock, the possibility to integrate with external heat sinks, appropriate process design and the scale of the plant. The scale of the plant should be adapted to the potential, regional, raw-material supply, but still be large enough to give economies of scale. The integration with heat sinks proved to be most important to achieve high energy-efficiency, but it was of somewhat less importance for the profitability. Development of pentose fermentation, leading to higher ethanol yields, was important to gain high profitability. Promising locations were identified in the county of Östergötland where integration with an existing 1st generation ethanol plant and district heating systems (DHSs) is possible, and in the county of Skåne where both a significant, potential straw supply and integration potential with DHSs are available.