Techno-Economic Analysis of Electrocatalytic CO2 Reduction into Methanol: A Comparative Study between Alkaline Flow Cell and Neutral Membrane Electrode Assembly

Abstract

Electrocatalytic CO2-reduction technology can convert CO2 into methanol and other chemicals using renewable electricity, but the techno-economic prospects of the large-scale electrocatalytic reduction in CO2 into methanol are not clear. This paper conducted sensitivity analysis to confirm the key parameters affecting the cost of methanol production from an alkaline flow cell and a neutral MEA electrolyzer, compared the cost of the two electrolyzers under laboratory data and optimized data scenarios, and analyzed the key parameter requirements of the two electrocatalytic systems to achieve profitable methanol production. The results show that electricity price, Faradaic efficiency, cell voltage, and crossover/carbonate formation ratio are the most sensitive parameters affecting the cost of methanol production. The alkaline flow cell had higher energy efficiency than the MEA cell, but the saving cost of electricity and the eletrolyzer cannot cover the cost of the regeneration of the electrolyte and CO2 lost to carbonate/bicarbonate, resulting in higher methanol production costs than the MEA cell. When the crossover/carbonate formation ratio is zero, the cost of methanol production in an alkaline flow cell and a neutral MEA cell can reach under 400 USD/tonne in the cases of energy efficiency more than 70% and 50%, respectively. Therefore, enhancing energy efficiency and ensuring a low crossover/carbonate formation ratio is important for improving the economy of electrocatalytic methanol production from CO2 reduction. Finally, suggestions on the development of electrocatalytic CO2 reduction into methanol in the future were proposed.