Industrial Symbiosis in the Biofuel Industry : Quantification of the Environmental Performance and Identification of Synergies

Sammanfattning: The production of biofuels has increased in recent years, to reduce the dependence on fossil fuels and mitigate climate change. However, current production practices are heavily criticized on their environmental sustainability. Life cycle assessments have therefore been used in policies and academic studies to assess the systems; with divergent results. In the coming years however, biofuel production practices must improve to meet strict environmental sustainability policies.The aims of the research presented in this thesis, are to explore and analyze concepts from industrial symbiosis (IS) to improve the efficiency and environmental performance of biofuel production and identify possible material and energy exchanges between biofuel producers and external industries.An exploration of potential material and energy exchanges resulted in a diverse set of possible exchanges. Many exchanges were identified between biofuel producers to make use of each other’s by-products. There is also large potential for exchanges with external industries, e.g. with the food, energy and chemical producing industries. As such, the biofuel industry and external industries have possibilities for potential collaboration and environmental performance improvements, though implementation of the exchanges may be influenced by many conditions.In order to analyze if concepts from IS can provide benefits to firms of an IS network, an approach was created which outlines how quantifications of IS networks can be produced using life cycle assessment literature for guidelines and methodological considerations. The approach offers methods for quantifying the environmental performance for firms of the IS network and an approach to distribute impacts and credits for the exchanges between firm, to test the assumed benefits for the firms of the IS network.Life cycle assessment, and the approach from this thesis, have been used to quantify the environmental performance of IS networks by building scenarios based on an example from an IS network of biofuel producers in Sweden. From the analyses, it has been found that exchanges of material and energy may offer environmental performance improvements for the IS network and for firms of the network. However, the results are dependent upon the methodological considerations of the assessments, including the reference system, functional unit and allocation methods, in addition to important processes such as the agricultural inputs for the system and energy systems employed.By using industrial symbiosis concepts, biofuel producers have possibilities to improve the environmental performance. This is done by making use of by-products and waste and diversifying their products, promoting a transition toward biorefinery systems and a bio-based economy for regional environmental sustainability.