Life cycle assessment approach for upcycling expanded polystyrene across industrial sectors

The recycling of polystyrene and its reuse in consumer products, such as bicycle helmets, is important to the implementation of a circular economy due to its high production volume and environmental recalcitrance. In this study, we conducted a streamlined life cycle assessment to compare the environmental impact of producing expandable polystyrene from primary sources with production from post-consumer waste. In addition, we evaluated the environmental impact of utilizing these two polystyrene feedstock materials in bicycle helmets, and we further compared these impacts to those associated with other compositional and packaging materials. We applied up-to-date manufacturing data and well-established life cycle inventory databases using the ReCiPe 2016 life cycle impact assessment method. The seventeen environmental impact categories evaluated exhibit beneficial net reductions (in the range of 0% to 45%) for the case study of using 50% post-consumer recycled expanded polystyrene. A focused analysis on global warming potential, fine particulate matter formation, freshwater ecotoxicity, human carcinogenic toxicity, mineral resource scarcity, and water consumption illustrates higher reductions in impact (in the range of 40%–45%) for global warming potential, fine particulate matter formation, and carcinogenicity and lower reductions in impact (in the range of 10%–15%) for freshwater toxicity and water consumption. Notably, the contribution of utilities is smaller than that of materials in most of the environmental impact categories, except for water consumption. In addition, the environmental impact is reduced when using 50% post-consumer polystyrene for the manufacturing of bicycle helmets, e.g., in the range of 5%–10% for global warming potential. The results demonstrate that the use of post-consumer recycled expanded polystyrene leads to considerable environmental impact reductions and that future studies considering novel recycling technologies and broader material selection choices should be pursued.