Ocean alkalinity enhancement

Ocean Alkalinity Enhancement (OAE) is a highly scalable marine carbon dioxide removal (mCDR) strategy that accelerates the Earth’s natural weathering processes. By dissolving alkaline minerals (like olivine or magnesium hydroxide) or utilizing electrochemistry to extract acid from seawater, OAE shifts the marine carbonate equilibrium to absorb more atmospheric CO2 and store it safely as dissolved bicarbonate for thousands of years. In 2026, the sector has transitioned from mesocosm experiments to large-scale coastal deployments, simultaneously offering a powerful tool to reverse local ocean acidification and protect vulnerable marine ecosystems like coral reefs.

The key directions of ocean alkalinity enhancement are:

1. Mineral Addition: Dispersing finely ground alkaline minerals (e.g., olivine, brucite) into coastal waters or ship wakes.
2. Electrochemical OAE: Using bipolar membrane electrodialysis to separate seawater into acidic and alkaline streams.
3. Coastal Weathering: Placing alkaline sand on beaches to weather naturally via tidal wave action.
4. Monitoring & Verification: Developing sensor networks and biogeochemical models to accurately quantify carbon drawdown.

Sectoral value chain#

[Alkalinity Sourcing] ──> [Processing & Transport] ──> [Ocean Dispersion] ──> [Chemical Equilibration]
                                  │
                          (MRV Sensors)
                                  │
                                  ▼
[Carbon Credits] <─── [Verification & Auditing] <─────┘

Value chain levels#

Cross-cutting technologies of the sector:

• Bipolar Membrane Electrodialysis: Highly efficient membranes for splitting seawater without chemical reagents.
• Biogeochemical Modeling: Supercomputer simulations predicting ocean current dispersion and carbonate chemistry.
• Autonomous Aquatic Gliders: Fleets of underwater drones equipped with high-precision pH and pCO2 sensors.

Ocean Alkalinity Enhancement leverages marine carbonate thermodynamics and advanced electrochemistry to permanently lock away carbon.

1. Carbonate Thermodynamics:
   • Adding alkalinity shifts the ocean equilibrium, converting dissolved CO2 into stable bicarbonate (HCO3-).
   • 1 mole of divalent cation (Ca2+, Mg2+) theoretically sequesters up to 1.7 moles of atmospheric CO2.
2. Bipolar Membrane Electrodialysis:
   • Applies an electric field to split water molecules, generating acidic and alkaline streams from seawater.
   • The acidic stream is safely neutralized or utilized industrially, while the alkaline stream is returned to the ocean.
3. Advanced MRV (Measurement, Reporting, Verification):
   • High-precision optode sensors continuously track pH shifts with an accuracy of 0.001 units.
   • Coupled hydrodynamic-biogeochemical models calculate the exact net carbon drawdown accounting for outgassing.