Comparative assessment of global warming impact and eco-efficiency of PS (polystyrene), PET (polyethylene terephthalate) and PLA (polylactic acid) boxes

The life cycle assessment is an important tool to assess the environmental impacts of petroleum- and bio-based plastics. This study assessed the global warming potential and eco-efficiency of single used boxes, namely polystyrene, polyethylene terephthalate and polylactic acid, from cradle to grave. The effects of carbon uptake from photosynthesis and land-use change during corn plantation on global warming potential of polylactic acid boxes were considered. The global warming impact of the studied materials under various waste management scenarios was studied and compared. It was found that polystyrene in landfill created the lowest global warming impact (51.4 kg CO2 equivalent). Next, polylactic acid with photosynthesis in compost exhibited the second greatest environmental benefits (152.2 kg CO2 equivalent). Whereas, polylactic acid with land-use change in landfill revealed the highest global warming impact (773.5 kg CO2 equivalent). The global warming impact of polylactic acid with photosynthesis was lower by 20-51% than that of polylactic acid with land-use change in all waste management scenarios. Polystyrene in landfill was the most favorable eco-efficiency because of its lowest total cost with relatively low global warming impact. In conclusion for bio-based boxes, polylactic acid with photosynthesis in compost showed the highest eco-efficiency. The eco-efficiency of polylactic acid boxes can be significantly improved by minimizing the resin prices and disposal in the suitable waste management by composting.