Seawater Battery Breakthrough: Energy Storage, Desalination, and Carbon Capture Combined

Researchers at Korea's Ulsan National Institute of Science and Technology have developed a seawater battery that does three things at once: stores renewable energy, partially desalinates water, and captures carbon dioxide. During charging, the battery separates sodium and chloride ions from seawater, which both stores energy and reduces salt content. During discharge, it absorbs CO2 and converts it into solid carbonates. The system uses about 40% less energy for salt removal than traditional reverse osmosis, though the output is brackish water, not yet drinkable without further treatment. The battery's energy storage cost is estimated at $0.10 per kilowatt-hour, avoiding expensive materials like cobalt and nickel. However, it relies on ceramic NASICON membranes that are costly and prone to fouling from seawater impurities. The carbon capture potential is estimated at 640 to 1,280 kilograms of CO2 per day while treating 150 cubic meters of seawater. The technology is at different readiness levels: energy storage is more advanced (TRL 5-6), while desalination and carbon capture are still in earlier stages (TRL 3-4). Applications include powering off-grid marine systems, supporting desalination plants with lower energy input, and helping industrial sites reduce emissions. The main hurdles are membrane durability, scalability, and proving real-world performance. If those are solved, this battery could become a practical tool for linking renewable energy, water treatment, and carbon removal in one package.