Using Solar Power Regulation to Electrochemically Capture Carbon Dioxide: Process Integration and Case Studies

This work focuses on the use of solar photovoltaic energy to capture carbon dioxide by means of a combined electrolyzer–absorption system and compares operating results obtained in two cases studies (operation during one clear and one cloudy day in March) in which real integration of solar photovoltaics, electrolyzer and absorption technologies is made at the bench-scale. The system is a part of a larger process (so-called EDEN⃝R , Electrochemically-based Decarbonizing ENergy) which aims to regulate solar photovoltaic energy using a reversible chloralkaline electrochemical cell. Results demonstrate the feasibility of the sequestering technology, which can produce chlorine and hydrogen but also the sequestration of CO2 and its transformation into a mixture of sodium chloride, bicarbonate, and carbonate, useful as raw matter. Efficiencies over 70% for chlorine, 60% for hydrogen and 90% for sodium hydroxide were obtained. The sequestration of carbon dioxide reached 24.4 mmol CO2/Ah with an average use of 1.6 mmol NaOH/mmol CO2. Important differences are found between the performance of the system in a clear and a cloudy day which point out the necessity of regulating the dosing of the electrochemically produced sodium hydroxide to optimize the sequestration of CO2.