A trade-off between carbon and water impacts in bio-based box production chains in Thailand: A case study of PS, PLAS, PLAS/starch, and PBS

Currently, bio-based plastics are considered the most promising and environmentally friendly alternative to replace petroleum-based plastics to reduce their environmental impacts. The aim of this research work is to assess and compare the life cycle impact of three types of bio-based boxes (namely, polylactic acid from sugarcane, polylactic acid from sugarcane-starch blends and polybutylene succinate from sugarcane and corn) and petroleum-based boxes of polystyrene. The locations of the plantation stage are focused in 4 provinces, namely, Kanchanaburi, Sakaeo, Prachinburi, and Chonburi provinces, in Thailand. The total impact using the external environmental cost (unit: THB equivalent) is performed at two impact categories: carbon footprint and fresh water consumption. The results from this study indicate that polybutylene succinate reveals the lowest water footprint at 0.38 m3 H2O of all the bio-based boxes and presents the second lowest water deprivation at 0.008 m3 H2O equivalent and the lowest carbon footprint at −0.06 kg CO2 equivalent. The lowest water footprints for all bio-based boxes production chains are found in Kanchanaburi and Chonburi provinces because the highest sugarcane and corn yield were observed, respectively, whereas, the minimum of water deprivation for all bio-based boxes production chains are clearly observed in Sakaeo province because of the lowest amount of chemicals used during plantation stage. The total impact on carbon footprint decreased by 26-69% for the production of bio-based boxes because CO2 absorption from the photosynthetic reactions during the plantation stages were included. In conclusion, for bio-based boxes, the polybutylene succinate box showed the lowest total externality cost of 0.046 THB equivalent on production chain in Sakaeo province. This externality accounts for 64-74% of total cost for freshwater consumption but only accounts for 26-36% of total cost for carbon footprint. These results are beneficial to supporting the development for establishing bio-plastics industry in aspects of water used and carbon footprint. Therefore, the effective strategies for preparing a sufficient supply of irrigation system or efficient water management and appropriate performance from agrochemicals used for supporting the feedstocks production to bio-plastics industry production chains should be proposed.