The oceans are the world’s sink of CO2. In fact, 30% of annual CO2 emissions are absorbed by the world's oceans. Equatic leverages a first-of-a-kind electrolytic approach that removes CO2 from the atmosphere and then uses the ocean's natural capacity to store carbon for millions of years.
The process exploits the enormous abundance of calcium and magnesium ions in seawater. By coupling carbon dioxide removal and generation of hydrogen as a green fuel it achieves two objectives essential for a de-carbonized economy:
- It immobilizes CO2 permanently in the ocean, as dissolved bicarbonate ions (in water), and in the form of solid mineral carbonates.
- It produces hydrogen, a green fuel that can replace fossil fuels, to thereby eliminating any further CO2 emissions.
As both outputs share the same equipment and capital investment, Equatic can achieve unique cost, another enabler of the decarbonized economy.
Our novel electrolytic process, developed by scientists at UCLA’s Institute for Carbon Management, is based on continuous (flow-through) electrolysis of seawater to permanently lock CO2 within stable carbonate solids and in the form of dissolved inorganic carbon (DIC). It is this permanent "lock-up" that allows the ocean to store the atmospheric CO2 that Equatic captures within the boundaries of our plants.
Seawater has contained dissolved inorganic carbon (DIC) for millions of years, and is in effect oversaturated with respect to calcium carbonate (as exemplified by the stability of sea shells). The Equatic process exploits this fact to immobilize carbon dioxide in the oceans for tens of thousands, if not millions of years. The natural alkalinity of seawater is restored by dissolving alkaline rocks prior to discharge, thereby keeping the natural composition of seawater intact.
The technology is being demonstrated with two pilots, one at the Port of Los Angeles and one in Singapore. Each of these first-of-a-kind plants removes ~100 kg of CO2 per day. Equatic has designed and built novel, two-chamber, flow-through electrolytic reactors and is validating and optimizing their performance with the two pilots. The pilots also verify that CO2 is being effectively removed from the atmosphere.
Based on the learnings from the two pilots, Equatic is already engineering the next scale of plant, which be able to remove thousands of metric tons of CO2 per year.
Measurement, Reporting, Verification
The net extent of CO2 removal accomplished by the Equatic process must be measurable, verifiable, reportable, additional, and durable. In addition, the potential for leakage, the environmental impact, and co-benefits must be considered. We can unambiguously calculate the net extent of CO2 removal effected by the Equatic process as follows:
We use mass balances to quantify carbon removal
Equatic Dissolved, CO2e (g CO2/m3 water) = mass % Mg(OH)2 × total mass of solids (g/m3 water) × (1.7 mol CO2/mol Mg(OH)2) × (44.01 g CO2/mol CO2) × (1 mol Mg(OH)2/58.3197 g Mg(OH)2)
Equatic Solid, CO2e (g CO2/m3 water) = mass % CaCO3 × total mass of solids (g/m3 water) × (1 mol CO2/mol CaCO3) × (44.01 g CO2/mol CO2) × (1 mol CaCO3/100.0869 g CaCO3)
These carbon removal factors indicate that 1.7 mol of CO2 is sequestered per mol Mg(OH)2 produced, whereas 1 mol of CO2 is removed per mol CaCO3 produced. The evasion of CO2 from seawater that can result from secondary CaCO3 precipitation in the ocean or the mixing of un-neutralized acid, is rigorously mitigated by our unique process configuration.
For the full scientific details behind these calculations, see: La Plante et al., 2023