Measuring the environmental performance of a circular system: Emergy and LCA approach on a recycle polystyrene system

Abstract

The search for sustainability has pointed to the need to transition from a linear to a circular model. However, such a transition is not trivial. Modifying production chains with the focus on reducing virgin raw materials consumption, cut emissions, and prevent waste generation implies implementing new processes and services, which can add considerable environmental impacts to the supply chain. This paper analyzes a real case from a production system aligned with circular economy principles. The production system consists of the manufacturing of baseboards made of recycled Expanded Polystyrene (EPS), obtained from an extensive reverse logistics system composed of different recycling processes. The system's potential environmental impacts were assessed by two widely used methodologies, Life Cycle Assessment (LCA) and Emergy Analysis (EMA). For comparison purposes, the analysis was carried out for a fictional linear production system, in which the baseboard would be made of virgin EPS. EMA attributed a lower emergy load to the circular scenario compared to the linear scenario (8.62E+15 seJ to recycled EPS versus 1.26E+16 seJ to virgin EPS). LCA results indicate both scenarios as environmental preferable depending on the impact category under analysis (e.g. circular system has better performance regarding global warming, while the linear scenario demonstrated better results under water consumption). For the circular scenario, EMA identified the main impact drivers, such as transportation and electricity consumption. From LCA perspective impacts are also driven by electricity consumption. However, differently from EMA, logistics were only significant for Land Use impact category whereas Liquefied Petroleum Gas consumption and, landfill air emissions were identified as impact hotspots. These convergences and differences between the findings of LCA and EMA have demonstrated potentially complementation to broaden available information related to systems, enabling decision makers to act effectively in improving the environmental performance of their production processes, especially when implementing circular practices.