UM3-LCE3-ISN: a methodology for multi-level life cycle environmental and economic evaluation of industrial symbiosis networks

Life cycle assessment (LCA) and life cycle costing (LCC) are state-of-the-art methods used to holistically measure the environmental and economic performance of industrial symbiosis networks (ISNs). Existing methodologies face a challenge in unifying LCA and LCC of an ISN in a single model that can disaggregate the network-level results to the entity and resource flow levels. This study introduces UM3-LCE3-ISN, a methodology for multi-level matrix-based modeling for life cycle environmental and economic evaluation of ISNs. The UM3-LCE3-ISN methodology is designed to conduct a process-based LCA and LCC of any ISN scenario. The methodology constructs a single matrix-based model that represents the physical and monetary flows of an ISN across the entire life cycle. The demand and price vectors in the model can be manipulated to produce LCA and LCC results of an ISN at the levels of the entire network, individual companies, and specific resource flows. A formalism is provided that outlines the steps for model construction and multi-level analysis. Verification of the model constructed can be done by producing scaled technology and monetary matrices of an ISN. UM3-LCE3-ISN is tested through a case study of an urban agri-food ISN comprising five entities engaged in open and closed-loop recycling. The case study results demonstrated that UM3-LCE3-ISN can be used to compute the life cycle environmental impacts and net present value of ISNs at the three different stakeholder levels. Only one matrix model was required for each scenario to compute the LCA and LCC results for multiple stakeholders through one computation as opposed to several computations in multiple separate models. UM3-LCE3-ISN can produce granular LCA and LCC results regarding specific waste-to-resource conversion processes within an ISN and their contribution to the environmental and economic performance of specific entities. Overall, UM3-LCE3-ISN is able to unify potential conflicting assumptions and data used by different models and obtain more holistic LCA and LCC results that are harmonized for stakeholders across different levels. The UM3-LCE3-ISN methodology can be applied in industrial symbiosis facilitation tools that allow diverse stakeholders such as policy-makers, urban planners, businesses, and product designers to operate on a common platform to determine the life cycle environmental and economic performance of an ISN from multiple perspectives of interest. This would allow diverse stakeholders to make holistic evidence-based decisions and strategies for developing ISNs in different sectors that enable a large-scale transition to a circular economy.