System and method for electrochemical ocean alkalinity enhancement

A method for enhancing alkalinity comprising:

• (i) providing a bipolar membrane electrodialysis device (BPMED) which comprises electrodes and at least one unit comprised of a brine compartment, an acid compartment, and a base compartment;
• (ii) flowing an aqueous brine solution through the base compartment at a first volumetric flow rate (fba) and through the brine compartment at a second volumetric flow rate (fbr), the aqueous brine solution comprising at least one divalent cation that precipitates out of the aqueous brine solution to form a solid precipitate when the aqueous brine solution is at or above a precipitating pH;
• (iii) applying a voltage between the electrodes at a current density to the BPMED device to form, in the base compartment, an enhanced pH alkaline brine product that has a pH higher than the pH of the brine but below the precipitating pH;
• (iv) maintaining, at the current density, the first volumetric flow rate through the base compartment at a rate sufficiently greater than the second volumetric flow rate through the brine compartment so as to keep the pH of the enhanced pH alkaline brine product formed in the base compartment below the precipitating pH;
• and
• (v) outputting the enhanced pH alkaline brine product from the base compartment.