Energy, Cost, and Environmental Assessments of Methanol Production via Electrochemical Reduction of CO2 from Biosyngas

Abstract

Electrochemical reduction of CO2 removed from biosyngas into value-added methanol (CH3OH) provides an attractive way to mitigate climate change, realize CO2 utilization, and improve the overall process efficiency of biomass gasification. However, the economic and environmental feasibilities of this technology are still unclear. In this work, economic and environmental assessments for the stand-alone CO2 electrochemical reduction (CO2R) toward CH3OH with ionic liquid as the electrolyte and the integrated process that combined CO2R with biomass gasification were conducted systematically to identify key economic drivers and provide technological indexes to be competitive. The results demonstrated that costs of investment associated with CO2R and electricity are the main contributors to the total production cost (TPC). Integration of CO2R with CO2 capture/purification and biomass gasification could decrease TPC by 28%-66% under the current and future conditions, highlighting the importance of process integration. Energy and environmental assessment revealed that the energy for CO2R dominated the main energy usage and CO2 emissions, and additionally, the energy structure has a great influence on environmental feasibility. All scenarios could provide climate benefits over the conventional coal-to-CH3OH process if renewable sources are used for electricity generation.