Abstract

Bio-based and biodegradable plastic materials have been developed in response to multiple environmental concerns regarding widespread use of conventional polymers. It is important to evaluate new plastics’ environmental performance against conventional plastics they replace through techniques such as life cycle assessment (LCA). This paper reviews significant LCA studies of bioplastics and discusses issues encountered, including allocation difficulties for multifunctional processes, assumptions about energy and the differences between cradle to gate and cradle to grave studies. Using renewable feedstock does not guarantee a plastic is environmentally friendly over its entire life cycle or even in just its production. For some fermentation based systems, considerable amounts of energy are used in the processes required to convert renewable biomass into a functionally equivalent alternative to petrochemical polymers. The sustainability benefits of using renewable feedstocks may be negated if this energy comes from non-renewable sources such as coal fired electricity. Using renewable energy sources, as well as renewable feedstocks, significantly improves eco-profiles of such bioplastics. Alternatively, direct modification of agro-polymers such as starch or protein, giving them thermoplastic properties, may use less energy than some fermentation based bioplastic technologies.