Cost competitiveness of sustainable bioplastic feedstocks – A Monte Carlo analysis for polylactic acid

Abstract

The production of plastics from biological resources is a promising option for decarbonizing plastic production and solving the plastic waste issue. The current practice of using food plants such as corn as feedstocks however entails sustainability issues related to agricultural land use. Alternative feedstocks in the form of by-products have been explored for some time but are yet awaiting to reach the stage of market readiness. Lack of cost competitiveness has been identified as one major obstacle. This paper undertakes the first comparative meta-analysis of the costs of producing Polylactic Acid (PLA), a leading bio-based plastic polymer, from two alternative feedstocks: corn grain and corn stover. Cost contributions of specific inputs and process stages are identified through a production chain perspective. By applying the Monte Carlo technique for the first time within a bioplastic cost analysis, uncertainties in current estimates are reflected. As uncertainty factors, both technological input requirements and the development of input prices are considered. Despite higher energy requirements, we estimate that corn stover-based PLA is already competitive with corn grain-based PLA in terms of variable costs, resulting from the lower costs of feedstock procurement. However, this is overshadowed by the disadvantage of higher fixed costs. Our long-term analysis stresses the importance of lowering fixed unit costs through upscaling and associated learning effects. A major restriction to upscaling represents the demand side. To render production from alternative feedstocks competitive, it is crucial to inform consumers about the environmental superiority of such a feedstock switch.