24th Pacific Science Congress (PSC-24)

Plastics are extensively used in industrial production and daily life owing to their low density, chemical stability, and mechanical strength. However, the rapid expansion of plastic production and inadequate end-of-life management have caused substantial greenhouse gas emissions and persistent leakage into the environment, resulting in the loss of embodied energy and material value. Addressing these challenges requires a systematic and quantitative approach to guide the sustainable transformation of plastic systems. This study develops a comprehensive life-cycle carbon footprint analysis framework to evaluate and drive sustainable technologies across the entire plastics value chain. Grounded in life cycle assessment (LCA) principles, the framework integrates process simulation, life-cycle inventory compilation, and scenario-based modeling to quantify material and energy flows, carbon emissions, and mitigation pathways. The analysis covers the full life cycle of plastics: upstream refinery and naphtha production; midstream polymerization and intermediates, including polyethylene, p-xylene, purified terephthalic acid, and polyethylene terephthalate; and downstream waste treatment routes such as incineration with energy recovery, mechanical recycling, and chemical recycling. Life-cycle inventories are constructed from process-level data combined with harmonized background databases, ensuring consistent system boundaries and data integrity. Scenario analysis explores renewable and hydrogen-based energy substitution, biomass feedstock integration, and circular reuse of post-consumer plastics. Results show that combining decarbonized energy supply, biomass-based feedstocks, and enhanced recycling efficiency can significantly reduce cradle-to-grave carbon footprints and dependence on virgin resources. The integrated portfolio delivers synergistic environmental gains across production, conversion, and end-of-life stages, particularly under cleaner power structures and quality-preserving collection systems. Comparative evaluation identifies trade-offs between mechanical and chemical recycling, while sensitivity analysis underscores uncertainties from background data and allocation methods. Overall, the proposed framework provides a systematic foundation for advancing low-carbon and sustainable life-cycle management of plastics, linking carbon footprint analysis with material circularity, renewable energy transition, and long-term scenario planning within a unified analytical structure.

Carbon footprint analysis,plastics,circular economy,sustainable management,life-cycle assessment