Direct seawater electrolysis

Electricity can split water into hydrogen fuel and oxygen. Seawater also contains salts and other substances that can damage the equipment. Some systems pass water through a protective membrane first. Can a larger ocean-based system keep producing clean gases through changing water, waves and power?[1] [2] [3]

In membrane-integrated seawater electrolysis, water passes to a protected electrolyte while unwanted ions are excluded; the electrolyser then produces hydrogen and oxygen. Water supply must track consumption as electrical power changes. The engineering target combines durable ion exclusion, gas purity and marine-scale throughput. A 2024 floating pilot ran for over 240 hours in ocean motion. A separate 2026 five-cell system ran for 500 hours with real seawater and external heating; its proposed waste-heat loop is modeled, with larger pilot validation still needed.[1] [2] [3]

Ocean pilots have produced hydrogen, but salt exclusion, fouling and changing conditions must remain under control over a useful operating life. A membrane and an electrolyser also have to supply and consume water at compatible rates.[1] [2] [3]

The remaining target combines marine-scale throughput, durable ion exclusion and gas purity. Long catalyst tests, short ocean trials and controlled membrane tests establish different parts of that target.[1] [2] [3]

Wind power at sea could be converted into hydrogen without bringing in a separate freshwater supply. The benefit depends on keeping the extra water-handling equipment economical and reliable, rather than trading the freshwater requirement for excessive energy use or maintenance.[1] [2]

Converting offshore electricity into hydrogen could combine a nearby energy supply and water source without a separate freshwater supply. Membrane integration can also keep seawater contaminants away from proven water-electrolysis components. Those benefits depend on the energy and upkeep of water transfer: the 2026 study separates its externally heated experiment from a proposed heat-recovery design. Establishing that design at useful scale would determine whether the integration actually saves resources during sustained production.[1] [2] [3]