Capture6 links direct air capture of carbon dioxide with ocean alkalinity enhancement to recover fresh water and help enable potential large-scale removal of carbon dioxide (CO₂) pollution.
Capture6 links the direct air capture of atmospheric CO2 with ocean alkalinity enhancement (OAE), aiming to deliver gigaton-scale carbon removal while supporting water security. The technology uses membranes to filter salt from salt water, producing a basic liquid solvent that then reacts with atmospheric CO2 to make alkaline solutions. These solutions can then be dispersed into marine surface waters to enhance the ocean’s ability to absorb more carbon dioxide from the air.
The Potential Advantages
By using existing water treatment and cooling technologies, Capture6 aims to easily and affordably deploy large-scale CO2 removal facilities in the next decade. By using salt water to remove CO2 directly from the air and converting it to alkaline solutions for OAE, Capture6 eliminates the need to mine, grind, and transport alkaline rocks. In utilizing brine waste streams from desalination plants, up to 80 percent can be recovered as fresh water, creating a meaningful connection between carbon removal and water security while also replacing the coastal release of brine with alkaline streams to convert a potential environmental harm to a benefit. Finally, linking OAE to Direct Air Capture lowers the price of effective CO2 removal across both pathways and helps to accelerate the deployment of large-scale facilities.
Monitoring, reporting, and verification (MRV) – the process of determining and verifying how much carbon has been removed and stored – is a key challenge for open system CO2 removal technologies. As the MRV process is developed, Capture6 seeks to create a methodology that defines its approach to handling uncertainty in measurement and modeling during OAE dispersals. The aim is to advance understanding of the balance between observational monitoring and modeling with the planned scale of future OAE deployments.