KAIST and MIT convert seawater CO2 into stone for permanent storage
KAIST and MIT researchers built an e-DOC device that turns dissolved CO2 in seawater into calcium carbonate, removing 80-90% of carbon in 120-hour tests.
Photo by Jess Loiterton on Pexels
Researchers at the Korea Advanced Institute of Science and Technology (KAIST) and the Massachusetts Institute of Technology (MIT) published a study on August 3, 2026 describing a marine carbon removal technology that converts carbon dioxide dissolved in seawater into calcium carbonate, a stable mineral, for what the team describes as virtually permanent storage. The work, led by KAIST’s Professor Dong-Yeun Koh of the Department of Chemical and Biomolecular Engineering with MIT’s Professor T. Alan Hatton, appeared in the journal Advanced Energy Materials under the title “A Compact Hollow Fiber Electrode Assembly Architecture for Continuous Electrochemical Marine Carbon Dioxide Removal.”
The technology, called e-DOC (electrochemical dissolved ocean carbon removal), addresses a problem that has limited earlier direct ocean capture designs: mineral scaling on electrodes, similar to limescale building up inside a kettle, which forces frequent cleaning or replacement and drives up energy and maintenance costs.
How the marine carbon removal technology works
The core of the system is a hollow fiber electrode assembly (HFEA), built from bundled, thread-like hollow electrodes. Calcium carbonate minerals form outside the electrode surface rather than directly on it, while hydrogen bubbles generated naturally during the electrochemical reaction act as a continuous brush that clears the electrode surface and prevents buildup. The reaction also produces high-purity hydrogen gas and magnesium hydroxide as byproducts alongside the mineralized carbon.
In tests using seawater from Jeju Island’s lava rock coastline, the device ran continuously and stably for more than 120 hours, removing between 80% and 90% of the dissolved inorganic carbon in the water while cutting electricity consumption by up to 54% compared with conventional electrode systems, according to the KAIST release.
Why mineral storage matters for ocean carbon capture
Removing dissolved CO2 from seawater lets the ocean absorb more carbon dioxide from the atmosphere to restore chemical equilibrium, the same underlying principle used by other direct ocean capture (DOC) approaches. Storing the removed carbon as calcium carbonate, rather than compressing and injecting captured CO2 into geological reservoirs, avoids the need for offshore pipelines or storage wells. The research was funded by Hyundai Motor Company and Kia, along with South Korea’s Global C.L.E.A.N. Program, run by the National Research Foundation of Korea under the Ministry of Science and ICT.
| Metric | Figure |
|---|---|
| Continuous stable operation | More than 120 hours |
| Dissolved inorganic carbon removed | 80-90% |
| Electricity consumption reduction | Up to 54% |
| Test location | Jeju Island lava seawater, South Korea |
| Byproducts | High-purity hydrogen, magnesium hydroxide |
| Publication | Advanced Energy Materials, August 3, 2026 |
The KAIST team describes the HFEA design as compact and modular, and expects it could scale into larger marine carbon removal systems for use aboard ships or on offshore platforms, though no commercial partners or deployment timeline beyond the funders have been announced. The approach joins a small but growing field of direct ocean capture efforts, including a pilot that Hitachi, MOL, and JAL began testing on Kume Island in Okinawa using US-based Captura Corp.’s technology.
Background
KAIST is a South Korean public research university founded in 1971 and based in Daejeon, with a mandate to advance science and engineering research and train specialists for the country’s technology sector. Its Department of Chemical and Biomolecular Engineering has an ongoing collaboration with MIT’s Hatton research group on electrochemical carbon capture methods, building on earlier seawater mineralization studies that used less energy-efficient electrode designs prone to scaling. The August 2026 e-DOC study extends that partnership with a device architecture the researchers say resolves the scaling problem that has constrained continuous operation in prior marine carbon removal systems.
Sources: KAIST (EurekAlert); Phys.org; Gasworld
Featured image: photo by Jess Loiterton on Pexels (free Pexels license).
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I specialize in sustainability education, curriculum co-creation, and early-stage project strategy. At WINSS, I craft articles on sustainability, transformative AI, and related topics. When I’m not writing, you’ll find me chasing the perfect sushi roll, exploring cities around the globe, or unwinding with my dog Puffy — the world’s most loyal sidekick.
