Integrating ex-ante and prospective life-cycle assessment for advancing the environmental impact analysis of emerging bio-based technologies

Abstract

Unlike the fossil-based alternatives, many emerging bio-based technologies are still at the early lab or pilot scale and are not representative of optimized industrial conditions. This makes a robust comparison of their environmental performances via life-cycle assessment (LCA) challenging. We propose a framework to combine scaling-up projections of early-stage technologies (ex-ante LCA) with the influence of future socio-economic scenarios (prospective LCA), using a range of new bio-based polymers produced from forest residues as case study. The combined framework takes a step-by-step approach in modifying process inventories and projecting them to a future industrial scale for the environmental impact assessment. In our case study, the climate change impact from lab-scale processes decreases from 105–471 kg CO2-eq./kg of polymer to 9–14 kg CO2-eq./kg after the application of ex-ante LCA, with the highest reduction (83 %) coming from identified process synergies (e.g., solvent recovering). Combining the ex-ante and prospective LCA additionally reduces the impact up to 56 % by 2050, relative to ex-ante LCA results only. Other environmental impacts decrease as well, particularly freshwater eutrophication (up to 99 % reduction), photochemical oxidant formation (99 %), and marine eutrophication (98 %). The framework secures a more robust comparison of emerging bio-based products with conventional fossil-based alternatives, and as such it helps the identification of the improvements in both the bio-based technological processes and background supply chains that are needed to make bio-based systems outperform their fossil counterparts. A consistent integration of ex-ante and prospective LCA is instrumental to prioritize research and investments for upscaling the early-stage technologies that are most promising from a sustainability perspective, and ultimately guide a sustainable transition towards a circular bioeconomy.