Life cycle and economic analysis of chemicals production via electrolytic (bi)carbonate and gaseous CO2 conversion

Abstract

Electrochemical CO2 reduction provides a new insight to produce value-added chemicals production, but it requires a large amount of energy inputs to support the process of CO2 capture (i.e., desorption and separation process). Carbon-based fuels production via electrolytic (bi)carbonate conversion can bypass the energy-intensive steps (desorption and separation), becoming more environmental-friendly compared to electrolytic gaseous CO2-to-chemicals conversion. Here, we comprehensively explore and assess the energy conversion and environmental impacts, and economic benefits of the (bi)carbonate-to-chemicals and gaseous CO2-to-chemicals conversions using life cycle and economic assessments. The results show that the (bi)carbonate-to-chemicals conversion promote the energy and environmental benefits but reduce the economic benefits. (Bi)carbonate-to-formate and -CO conversion show low net energy ratio (1.90 and 1.93, respectively) and Greenhouse gas emissions (−0.5238 and −0.6287 t CO2-eq/t CO2 gas injection, respectively). While gaseous CO2-to-formate and -CO conversion are more industrially feasible for commercial application due to their lower overpotentials, higher current density, and higher Faradaic efficiency. Additionally, the sensitivity analysis show that the (bi)carbonate-to-chemicals systems are more promising through reducing the overpotential, enhancing the current density and Faradaic efficiency of the systems. This work demonstrates that electrolytic (bi)carbonate-to-chemicals conversion systems are eco-friendly, and give a theoretical guide to develop this energy-efficient CO2 utilization approach.