New indicator for comparing the energy performance of CO2 utilization concepts

Abstract

CO2 utilization is increasingly considered a greenhouse gas abatement strategy alternatively to CO2 storage. Existing indicators that assess the performance of CO2 utilization options often provide an incomplete perspective and are unsuitable to compare different utilization options with different functionality (e.g. plastics and fuels). This study introduces a new performance indicator for CO2 utilization options: Specific Primary Energy Consumption per unit of Fossil feedstock Replaced (SPECFER). This indicator, expressed in MJ/MJ, provides a proxy for the energy efficiency of which CO2 conversion options can replace fossil feedstock required in conventional processes. Three CO2 utilization case studies (CO2 based methanol, polyols and dimethyl ether) are used to show the application and effectiveness of the SPECFER indicator. Among the case studies, only CO2 conversion into polyol appears particularly efficient (SPECFER of 0.05 MJ/MJ), while the other options are not (SPECFER of > 1 MJ/MJ). The paper shows that the SPECFER indicator adds key insights compared to conventional indicators to the effectiveness of CO2 utilization options and is a promising indicator complementary to CO2 emissions reduction or life cycle greenhouse gas reduction potential. The SPECFER thus improves the understanding of the performance of CO2 utilization and enables the possibility to distinctly compare different CO2 converting utilization technologies.