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:

  1. It immobilizes CO2 permanently in the ocean, as dissolved bicarbonate ions (in water), and in the form of solid mineral carbonates.
  2. 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.

This illustration outlines the UCLA team's single-step carbon sequestration and storage concept.
Seawater inflow: Seawater is oversaturated with respect to Ca- and Mg-carbonate.
The electrolyzer splits water into hydrogen and oxygen gas while producing alkalinity and acidity. The alkalinity promotes carbon dioxide removal.
The carbon dioxide-depleted seawater is “replenished with carbon dioxide” by bubbling atmospheric air through it - thereby removing carbon dioxide, directly, from the atmosphere.
Hydrogen gas is processed for sale as a green fuel.
The acidity produced during electrolysis is neutralized by the dissolution of alkaline rock.
The seawater discharged into the ocean is chemically comparable to the seawater taken into the process.
This illustration outlines Equatic's electrolytic carbon dioxide removal (CDR) concept.
  1. Seawater inflow - seawater is oversaturated with respect to CaCO3.
  2. Electrolyzer modules split water into hydrogen gas and oxygen gas, thereby mineralizing CO2.
  3. The CO2-depleted seawater is “refilled” by bubbling air through it - the process thereby removes CO2 directly from the atmosphere.
  4. Hydrogen gas is captured for selling as a green fuel.
  5. The acidic output of the electrolyzers is neutralized by dissolving rock into it.
  6. The seawater discharged into the ocean is as clean as when it was taken from the ocean - the processing consists only of CO2 depletion, refilling with ambient air and and dissolution of rock.

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 Implementation

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.

This illustration outlines the UCLA team's single-step carbon sequestration and storage concept.
The pilot plants resemble forthcoming commercial-scale plants in terms of: e.g., power electronics, seawater intake, electrolyzer architecture, gas processing, and sensors and control instrumentation.
The pilot plants incorporate commercial power electronics to rapidly build commercial-scale plants.
Filtered seawater is taken into the plant from a single “master” intake point.
The pilot plant’s electrolyzers demonstrate and validate advanced technology concepts including low energy demand, high-rate seawater processing, and a scalable manufacturing approach to ensure accelerated and expedited commercialization.
This illustration outlines Equatic's electrolytic carbon dioxide removal (CDR) concept.
  1. The pilots have all the elements that the commercial-scale plant will have: power supply, seawater intake, electrolysis, capturing of gases and neutralization with rock.
  2. The power supply of the pilot will simulate the situation in the commercial-scale plants.
  3. Seawater intake.
  4. The electrolyzers used in the pilots are designed to demonstrate technological aspects such as energy efficiency and hydrodynamics. The scale of the modules is already similar to the scale planned for commercial-scale plants.

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

Total Carbon Removal CO2e Drawdown CO2eEmissions CO2e
where, Emissions CO2e includes the total embodied CO2 emissions from material and energy use (e.g., the grid emissions factor of electricity, electrode fabrication, etc.), and:
Drawdown CO2e Equatic Dissolved, CO2e Equatic Solid, CO2eEvasion from seawater
The CO2 sequestered as dissolved HCO3 and CO32– ions, and solid carbonates can be quantified unambiguously by weighing the masses of Mg(OH)2 and CaCO3 produced, and multiplying these masses by a carbon removal factor, as follows (in units of g CO2 per m3 of water processed):

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