Economic Viability\nof Integrated CO<sub>2</sub> Capture\nand Conversion

The capture of CO<sub>2</sub> using alkaline solutions\nrequires\nsignificant thermal energy to release CO<sub>2</sub> from a (bi)carbonate-enriched\nsolution. This release of CO<sub>2</sub> can instead be performed\nelectrochemically with a “bicarbonate electrolyzer”.\nThe bicarbonate electrolyzer forms acid equivalents to convert a (bi)carbonate-enriched\neluent from a CO<sub>2</sub> capture unit into CO<sub>2</sub> and,\nin turn, an upgraded carbon product such as CO and ethylene. There\nexists a tension for this closed-loop cycle to be put into practice:\na smaller CO<sub>2</sub> capture unit is required when using a more\ncaustic CO<sub>2</sub> capture solution, yet the electrolyzer works\nmore effectively at a lower pH. Here, we elaborate on three different\nmethods to align different pH regimes to couple air capture to CO<sub>2</sub> electrolysis. We also use a mass-balance model to assess\nthe commercial viability of a reactive carbon capture system that\nintegrates the CO<sub>2</sub> capture unit with a bicarbonate electrolyzer\nto show a levelized CO breakeven price below $1 kg<sub>CO</sub><sup>–1</sup>. These economics, coupled with the other practical\nadvantages of providing an electrolyzer with a liquid feedstock, present\na compelling case for reactive carbon capture.