Limitations of life cycle assessment in circular cascading bio-based systems

Life Cycle Assessment (LCA) is an established and widely used methodology for evaluating the environmental impacts of a product, yet its application in circular bio-based systems may be challenging. In bioresource valorization, the system cradle and classification of streams as wastes or co-products are not always unambiguous. This study examines the usability of LCAs in assessing cascading bio-based materials, and how the boundary and flow classification choices influence the outcome. We performed multiple Cradle-to-Gate LCAs with different scenarios for two cascading bio-based materials, examining how cradle boundary choices and flow classification as waste streams vs. potential co-products affect the results. The findings demonstrate significant differences in LCA results deriving from different interpretations of the product system and its evolution. This implies that LCA results are highly dependent on scope definition and process modeling decisions, highlighting limitations in its use as an objective decision-support method in emerging circular bio-based value chains.