A case study on closed-loop recycling of co-polyester plates – Assessment of material quality and life-cycle energy and greenhouse gas performance

Material quality, and opportunities for multiple reprocessing, need to be considered when analysing the overall carbon footprint and energy efficiency of plastic products in life cycle assessments. This is rarely done today. This paper presents a case study evaluating a closed-loop recycling system involving a plastics manufacturer in Sweden which produces and reprocesses multiple-use plastic dining plates. The study involves (i) analysing the physical properties and food safety and (ii) assessing the life-cycle energy and greenhouse gas (GHG) performance of the closed-loop recycling system and three other conventional options. The results show certain deterioration in material quality of the plastic plates after six reprocessing cycles but maintained functionality and fulfilment of the food safety requirements. Furthermore, the results show that the life-cycle GHG emissions for the closed-loop recycling system correspond to 20–60% of those of the alternative systems. The primary energy use for the closed-loop recycling system amounts to 50–60% of that of two alternative systems, while it is higher compared to the system that involves one recycling loop followed by waste incineration with energy recovery. This study demonstrates the importance of taking material quality into account in life cycle assessments and confirms the GHG benefits of closed-loop systems.