Environmental impacts and mitigation potentials of CO2-based biodegradable plastic based on life cycle assessment – A case study of poly(propylene carbonate)

Abstract

CO2-based biodegradable plastics are potential solutions for reducing fossil-fuel consumption, mitigating climate change, and addressing plastic pollution by reducing plastic waste accumulation. Poly(propylene carbonate) (PPC) is a commercial CO2-based biodegradable plastic derived from CO2 and propylene oxide (PO), and it has been used in flexible packaging and mulching film applications. However, the environmental performance of PPC is still unknown. Since China has become the largest producer of PPC in the world, this study takes the industrial production technologies of PPC and its feedstocks in China as an example. The cradle-to-gate life-cycle inventory of PPC resin was compiled, and life-cycle impact assessment was performed to assess the environmental impacts of PPC and mitigation potentials based on the ReCiPe 2016 method. Results indicated that PPC synthesis has the greatest impact on the environment (contributions of 38–95% of 16 environmental impact categories), followed by PO production. Technological innovation and renewable energy substitution scenarios were developed to explore the mitigation potential of PPC. We found that supercritical polymerization technology has greater mitigation potential than photovoltaic power substitution, which could reduce 17 impact categories of PPC by 17–96% by reducing energy and dichloromethane consumption during PPC synthesis. Photovoltaic power substitution reduced 2–22% of 11 impact categories of PPC. Compared with conventional plastics, PPC had advantages over conventional plastics in terms of 17 impact categories. The environmental impacts of PPC were 2–98% lower than those of conventional plastics. This study emphasizes the importance of technological innovation in reducing the lifecycle environmental impacts of PPC and provides a basis for environmental performance of CO2-based biodegradable plastics and the potential to replace conventional plastics. Policy implications for innovations in synthesis technology, sustainable feedstocks and environmental impact assessment were proposed, which could provide valuable insights for practitioners and policymakers in enhancing the sustainability of the plastics industry through biodegradable plastic alternatives.