Electrochemically Driven Sorbent-Mediated Recovery of CO2 in Marine Inorganic Carbon Extraction Processes

Abstract

The oceans act as a sink for atmospheric CO2, absorbing more than a quarter of global emissions annually. Technologies for marine inorganic carbon dioxide removal (mCDR) have recently gained attention as a means of leveraging this effect to reduce environmental CO2 concentrations. In pH-swing mCDR systems, electrochemical acidification drives the conversion of dissolved inorganic carbon (DIC) in seawater to CO2, which is then removed through vacuum stripping before the water is realkalinized and released to the ocean to draw down atmospheric carbon. While most research has focused on the pH-swing process itself, little attention has been devoted to the stripping step, which is particularly capital- and energy-intensive and indiscriminately removes dissolved oxygen, which is vital to marine life. In this work, we present a framework for an alternative sorbent-mediated CO2 concentration process, analyzing and experimentally demonstrating an electrochemically mediated embodiment. A comparative energetic and technoeconomic assessment is presented, evaluating performance relative to state-of-the-art vacuum processes and indicating that a sorbent-mediated extraction process can be a viable alternative.