A standardized methodology for economic and carbon footprint assessment of CO2 to transport fuels: Comparison of novel bicarbonate electrolysis with competing pathways

Abstract

Early evaluation of carbon capture and utilization (CCU) pathways in terms of cost and emission reductions is critical in guiding future R&D and commercialization. However, such evaluation is challenging due to varying technology readiness levels (TRL) of pathways, unavailability of cost and emission data for new technologies and uncertainty of performance parameters of lab scale technologies. In this study, we propose a standardized methodology that allow comparing synthetic fuel production pathways based on early stage lab scale CO2 electrolysis technologies with mature CCU technologies and incumbent technologies. This methodology provides guidelines for defining pathways, modeling and cost and carbon footprint (CF) assessment supported by a bottom-up framework to scale- up the costs and CF of lab scale technologies. We apply the developed methodology to evaluate Fischer-Tropsh synthesis (FTS) fuel production pathways based on bicarbonate electrolysis, a novel early stage CO2 electroreduction technology with integrated CO2 capture, and reverse water gas shift (RWGS) reaction, a mature thermocatalytic CO2 conversion technology. The cost of diesel fuel production using RWGS and bicarbonate electrolysis pathways were 1.7 $/L and 1.5 $/L, respectively, which is more than 140% of current cost of diesel. Nevertheless, both pathways were able to achieve significant emissions reductions with bicarbonate electrolysis reducing 90% and RWGS reducing at 70% compared to conventional diesel. Based on the uncertainties of calculated cost, neither pathway is more economically competitive than the other. However bicarbonate electrolysis pathway offer more opportunities for emission reduction as most of its energy demand can be provided by renewable electricity. RWGS pathway with relatively higher thermal energy demand will need to rely on high level of energy recovery and integration to achieve similar emission reductions.