Combined Physisorption and Electrochemistry System for Modular Direct CO2 Capture and Storage

Scientists agree that isolated changes to the energy grid are insufficient to mitigate many detrimental impacts of anthropogenic climate change on human and ecological health. Novel, sustainable, and modular carbon dioxide removal (CDR) technologies offer options to mitigate impacts. The proposed direct air capture (DAC) system pairs physisorption in a zeolite-packed bed reactor with electrochemistry to precipitate and store captured carbon dioxide (CO
2
) as calcium carbonate (CaCO
3
). The sorption column produces an outlet stream 2,230 times more concentrated than ambient air, with a CO
2
concentration of 94.7%. This CO
2
-rich stream is fed into the cathode chamber of an electrochemical cell, which is filled with hard membrane filtration reject water. The electrochemical cell maintains an alkaline pH, allowing the gaseous CO
2
-rich stream to dissolve in the high hardness solution and form carbonate ions. Carbonate ions react with calcium ions present in the solution to form CaC0
3
. Bench scale testing has resulted in qualitative evidence of CaCO
3
formation. The system generates no waste during operation, and CaCO
3
is a stable, nontoxic solid which can persist indefinitely at ambient conditions. Based on the bench-scale model, the full-scale design removes 131 gross tons of CO
2
from ambient air every year, recovering the CO
2
emitted during technology construction, operation, and ultimate decommissioning over a 30-year lifetime. Seven modules, each consisting of 100 adsorption columns and two electrochemical cells, capture 100 net tons of CO
2
annually.