Deep Eutectic Solvents Reduce the Life Cycle Environmental Impacts and Energy Demands of Carbon Dioxide Capture

Abstract

Deep eutectic solvents (DESs) are emerging as prospective decarbonization media. Past studies have focused on their enhanced capacity to absorb carbon dioxide (CO2) from flue gas compared with conventional CO2 capture systems. However, it is also important to assess the environmental impacts and energy demands of DES-based CO2 capture systems, which could potentially undermine the rationale for their adoption as sustainable solvents. Here, we develop complete conceptual process designs of CO2 capture systems using DES-based systems. The environmental impacts and energy demands of DES-based CO2 capture systems are modeled, simulated, heat-integrated, optimized, and compared with a conventional Selexol process. Results show that, compared with the Selexol-based process, DES-based CO2 capture systems reduce environmental impacts by approximately 35% largely due to proportionately lower energy requirements. In a comparison of two DES-based alternatives, choline chloride-urea requires less energy and results in lower adverse environmental impacts compared with choline chloride-monoethanolamine. These results suggest the need for more research in this field to design DES systems that best conserve environmental and energy resources.