STEP carbon capture – The barium advantage

•Carbon dioxide is directly captured from the air in a single STEP using inexpensive nickel and steel electrodes at high efficiency using solar thermal energy.•A new barium carbonate containing electrolyte further increases the direct carbon dioxide absorption.•The carbon product is a valuable, stable and easy to store.•The process occurs at low energy and high rates consistent with other cost effective industrial electrochemical processes.•STEP (Solar Thermal Electrochemical Process) is a comprehensive solution to decrease atmospheric carbon dioxide to pre-industrial levels.

We have recently introduced the theory of the Solar Thermal Electrochemical Process for carbon capture and utilization (STEP carbon). We have also provided experimental validation of that theory using electrolysis of molten lithium and eutectic alkali carbonates at high (∼50%) solar efficiency and high rate, and delineated the materials required to use STEP carbon to decrease atmospheric CO2 to preindustrial levels in ten years. In this communication an effective, alternative STEP carbon electrolyte is introduced. It is demonstrated thermodynamically that barium carbonate can provide more than an order of magnitude greater affinity for direct carbon dioxide absorption from the air than our prior lithium carbonate electrolyte. It is demonstrated experimentally that molten barium carbonate mixtures provide an effective medium for the direct electrolytic reduction of absorbed carbon dioxide at high rate and lower energy. The products of the electrolysis are graphite, which is readily stored as a valued added commodity for future generations, and oxygen. The electrolyte is not consumed in this carbon dioxide splitting process.

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