Nature Energy, Published online: 15 September 2026; doi:10.1038/s41560-026-02136-0

Seawater is an attractive feedstock for hydrogen production that overcomes community concerns about fresh water; however, electrolysis of seawater remains challenging. Now, a coupled alkaline water electrolysis and vacuum distillation in a unified process overcomes those challenges by using waste heat to treat seawater, enabling 250 kW-scale efficient co-production of hydrogen and fresh water.