Techno-economic and life cycle assessment of a tandem CO2 and plastic waste-to-fuels system

Abstract

The transition towards a circular and low-carbon economy requires integrated solutions that enable the simultaneous valorization of waste streams and carbon dioxide. In this context, this study investigates a tandem system combining an electrochemical reactor (PV-EC) and a photo-electrochemical reactor (PEC) for the conversion of CO 2 and ethylene glycol derived from plastic waste into fuels and valuable chemical products (including glycolic acid). The planned research includes an economic analysis, encompassing capital expenditure estimation and investment profitability assessment using the Net Present Value (NPV) method, as well as a Life Cycle Assessment (LCA) aimed at evaluating the environmental impact of the proposed technology. Economic analysis revealed that profitability is mainly determined by the selling price of glycolic acid and the cost of renewable electricity, with glycolic acid accounting for nearly 85 % of total revenue. However, n-propanol is prioritized as the main target product and basis for the Functional Unit because the process was specifically designed for CO2 reduction into high-density liquid fuels. LCA shows that ethylene glycol dominates the environmental footprint, while the PV-EC configuration outperforms PEC due to lower glycol demand and reduced electricity consumption. These results highlight the system as a dual-purpose platform where n-propanol serves as the primary energy carrier while glycolic acid provides the required economic viability. Additionally, reducing ethylene glycol use via low-impact supply chains further improves environmental performance. This approach highlights the potential of the tandem reactor system for sustainable fuel and chemical production within a low-carbon, circular economy framework.