Land-use change emissions: How green are the bioplastics?

Recently, a discussion has emerged around greenhouse gas emissions due to direct and indirect land use change (LUC) of expanding agricultural areas dedicated to bio-products production. Converting rainforests, peatlands, savannas, or grasslands to produce food crop-based bio-products creates a carbon debt by releasing 9 to 170 times more CO2 than the annual greenhouse gas (GHG) reductions that these bio-products (such as the bioplastics) would provide by displacing petroleum-based products (conventional plastics). In this work, we demonstrate the importance of accounting for the LUC emissions in the LCA studies devoted to the analysis of the environmental impact of bio-based products and in particular of the bioplastics. To this end, an original case study has been carried out on the comparison between the LCAs of shoppers made from Mater-Bi (corn-based bioplastic) and polyethylene, including the LUC emissions. The obtained results highlight the strong influence of the LUC emissions on the GHGs saving achievable by displacing petroleum-based plastics with bioplastics and point out the importance of using waste biomass or biomass grown on degraded and abandoned agricultural lands to produce bioplastics that, in this manner, can offer immediate and sustained GHG advantages. (C) 2010 American Institute of Chemical Engineers Environ Prog, 30: 685-691, 2011