This research addresses emergent societal concerns driving national policies that seek to replace or reduce the use of petro-based plastics. Whilst environmental pollution by plastics is the dominant contemporary driver, alternatives will also need to demonstrate wider environmental and social benefits, not least the reduction of Greenhouse Gas (GHG) emissions. Biodegradable plastics produced from bio-based Succinic Acid (SA) are evaluated as an alternative to petro-based plastics in the context of the transition to a post-petroleum era.
A case study-based methodology was adopted that uses a feedstock catchment area near Hull, England, to provide high spatial and temporal resolution bio-physical, agronomic and climatic data to parameterise quantitative models for crop growth, nitrogen and carbon turnover and life cycle assessment (LCA). The main research questions are: (1) how can the feedstock availability of lignocellulosic biomass (LCB) be optimized, and; (2) can the associated GHG emissions of the commercial scale production of LCB-derived SA be reduced by the using agricultural residues and/or perennial, LCB crops?
The results of this case study suggest that significant environmental benefits would result from the adoption of a mixed LCB resourcing strategy. Introducing the perennial grass crop Miscanthus into the arable landscape to replace winter wheat on selected low quality, and environmentally vulnerable soils (8% of the total area) is the main driver for the benefits. A ‘mixed production’ (MP) scenario, using Miscanthus and winter wheat, and a ‘winter wheat only’ single production (SP) scenario, were developed to investigate the productivity and the potential climate change mitigation impacts arising from the proposed land use change strategy i.e. a shift from the SP to MP scenarios.
LCAs were conducted to explore the climate mitigation potential of LCB-based SA production. Integrated feedstock provision strategies that include perennial-derived LCB are found to be crucial for the overall climate mitigation performance of bio-plastics. A significant bioeconomy and agricultural opportunity has been identified for the provision of LCB-derived bio-plastics from dedicated, perennial crops. Scenarios without the perennial crop resulted in GHG emission balances of bio-SA based plastics that were similar to grain and petro-based plastics. In the scenario of Miscanthus being cultivated on low-quality soils, the LCB-based SA life cycle results in a persistent net carbon sink being generated.