Direct Air Capture Utilizing Hydrogen-Assisted Carbonate Electrolysis

Reduction of greenhouse gases is vital for the long-term environmental health of the planet. A large portion of the CO2 emitted each year in the United States is released from distributed sources, like cars, smaller factories, and farms. Direct capture of CO2 from ambient air is therefore necessary for the eventual reduction of greenhouse gas emissions in the atmosphere. However, capturing the CO2 in ambient air presents a great challenge due to the dilute nature of the CO2, requiring different strategies than carbon capture from concentrated CO2 waste streams. We propose a novel process for the capture and containment of CO2 from air into a purified, concentrated CO2 stream that can be redirected for use as a feedstock for a wide variety of applications, including chemical manufacturing and syngas formation. The CO2 is captured in a concentrated KOH solution using a high-surface area contactor to form potassium carbonate. The potassium carbonate is then efficiently electrolyzed in a hydrogen-assisted process that reduces the operating potential, increasing the electrical efficiency of the process while generating concentrated and purified CO2. Water, hydrogen, and KOH are also regenerated as byproducts that can be recycled back into the CO2 capture and electrolysis processes, reducing both overall energy and chemical consumption. This process has the potential for large scale-up, with no environmental limitations and virtually no chemical waste generated. This work directly addresses the goals of ARPA-E in seeking to establish robust, energy efficient, and low-cost strategies for direct removal of carbon dioxide from ambient air.