Circles, lines and bars: bringing life cycle thinking to evaluating circular economy concepts

Many of the materials and chemical in society are used in linear fashion – they are made, used and disposed of. There is growing interest in steering society towards more circular value chains: make, use, and then reuse, repurpose or recycle. Using materials in a more circular way can mimic natural processes and may be more sustainable than more linear ways. Emerging metrics for and evaluations of “circularity” of a process, product or company often focus exclusively on material flows. Sustainability is a broader concept which includes not only consideration of material flows, but also energy use, emissions and the impact of these. Life cycle assessment (LCA) is a methodology that is well suited for creating a comprehensive evaluation of the potential environmental impacts of new “circular” products or processes. This presentation will use LCA to evaluate a hypothetical process (or processes) for recycling waste plastics back into “good as virgin” plastics. The example will show the utility of LCA as a tool an approach to clearly define under which conditions a circular process is indeed more sustainable and when it is not. This insight can be used to define the critical conditions beyond the process technology (material supply, power sources, geography, other waste management) that can define success.