Comparative assessment of the environmental profile of PLA and PET drinking water bottles from a life cycle perspective

Bioplastic polymer that is produced from cassava has been considered the most promising alternative to conventional plastics as there is an abundant renewable resource in Thailand. The objective of this study was to analyze the life cycle environmental performance of polylactic acid (PLA) drinking water bottles produced in Thailand with an emphasis on different end-of-life scenarios. The functional unit was set at 1000 units of 250-ml drinking water bottles. The system boundary of the study covered all stages in the life cycle, including cultivation and harvesting, cassava starch production, transportation, glucose production, the polymerization process to produce PLA resin, PLA bottles production, and disposal process. The input–output data included the use of resources (water, chemicals, materials), energy (electricity, fuels), and all emissions based on the functional unit. The life cycle environmental performance of PLA drinking water bottles was compared with that of polyethylene terephthalate (PET) bottles for the same functional unit. The global warming potential, fossil energy demand, acidification, eutrophication, and human toxicity were selected in the analysis. The results obtained in this study showed that the environmental performance of cassava-based PLA bottles was better than PET bottles in terms of global warming, reduction of dependency on fossil energy, and human toxicity. In addition, it was shown that improving cassava starch process by combining with biogas production and utilization will lead to significant reduction in global warming potential and eutrophication potential.