Saline Water-Based Mineralization Pathway for Gigatonne-Scale CO₂Management

Abstract

This perspective proposes a potential pathway to diminish atmospheric CO2 accumulations which is distinct from traditional carbon capture and geological sequestration strategies and from existing negative emissions technologies (NETs). Unlike conventional sorbent- or solvent-based CO2 capture processes where substantial energy expenditures are associated with demixing and desorbing CO2, the single-step carbon sequestration and storage (sCS2) approach relies on electrolytic carbonate mineral precipitation using renewable energy within a simple and scalable process design. Although numerous approaches have implied electrolysis for carbon management, the sCS2 approach is unique in the following ways: (1) CO2 mineralization for promoting solid carbonate formation: The thermodynamic and kinetic barriers to carbonate precipitation are overcome by direct and in situ electrochemical forcing to stabilize dissolved inorganic carbon and divalent cations [Ca,Mg] to form carbonate minerals. (2) Flow-through membraneless electrolysis: A flowing electrolyte (seawater) is dissociated while in motion. The process utilizes cost-effective mesh electrodes while also decreasing the number of components and assembly steps and reducing the risk of device failure. (3) Integrated electrolytic reactor–rotary drum filter: An electroactive thin-film mesh cathode (eTFC) is suggested to be integrated within a rotary drum filter configuration, allowing for the filtration of dilute and polydispersed mineral precipitates at a low energy cost. These attributes render sCS2 as an approach worthy of more detailed evaluation, development, and scaling for global-scale carbon management.

Hydrochemical and Stable Isotope Analyses Show Limited Interactions Between Groundwater and Lake Water in the Lake Bosomtwi Impact Crater, Ghana.

“…Under such conditions, the groundwater gains high Si content over relatively short residence time. And where the dissolution of plagioclase is present, a 2:1 Si to Na ratio is expected (Garrels and Mackenzie, 1967;La Plante et al, 2021). This is consistent with the assertion that the high levels of Si in C1 members resulted from the aforementioned processes while CO2-charged meteoric waters recharged groundwater, and in the process dissolved a sodium rich plagioclase feldspar such as albite, which is common among the rocks of the study area.…”

Controls on CO2 Mineralization Using Natural and Industrial Alkaline Solids under Ambient Conditions

“…Based on current production rates, these waters can provide nearly 1 Gt of Mg and Ca in total per year. − Moreover, seawater is a massive reservoir of divalent cations, with global inventories amounting to 520,000 Gt Ca and 1,272,000 Gt Mg . So long as the ocean’s chemistry is not detrimentally affected, there may be additional opportunities in using ocean-derived Ca and Mg for CO 2 mineralization …”

Direct air capture: process technology, techno-economic and socio-political challenges

“…322 Additionally, examples are beginning to appear where electrochemicallydriven pH swing methods are used to reversibly generate and consume hydroxide, [323][324][325] and where electrochemical methods are used to separate CO 2 from water or seawater as a potential alternative to DAC. [326][327][328][329][330] To further develop electrochemical processes for DAC generally, key challenges include reducing the cost of the materials employed within the devices (particularly the case for membranes), understanding the impact of other components of air (particularly O 2 ), and gaining a deeper knowledge of molecular scale mechanism to further iterate materials design.…”