Advanced materials and system innovations for seawater electrolysis in hybrid renewable energy systems: Toward sustainable hydrogen production

Seawater electrolysis for hydrogen production represents a promising pathway within the global energy transition. It aims to advance clean energy, resource sustainability, and climate-neutral development. Unlike freshwater electrolysis, which competes with limited freshwater supplies, seawater offers an abundant and sustainable feedstock. It is advantageous for coastal and island regions. However, the direct utilization of seawater poses significant technical challenges, including severe electrode corrosion, chlorine evolution, cathodic scaling, and membrane degradation. It leads to compromised system performance and longevity. Recent advances in catalysts, protective coatings, and ion-exchange membranes have begun to mitigate these barriers. These advances can enable improved selectivity, stability, and efficiency in saline environments. In parallel, hybrid renewable energy systems (HRES) are integrating solar, wind, wave, geothermal, and biomass energy with hydrogen storage. It offers versatile solutions to renewable intermittency, thereby enhancing long-term energy reliability. When coupled with seawater electrolysis, HRES creates synergies at the energy–water nexus, enabling opportunities ranging from distributed self-sufficiency to large-scale hydrogen export. Although the current cost of hydrogen derived from seawater exceeds that of freshwater-based systems, techno-economic assessments suggest that economies of scale, enhanced system durability, and declining renewable energy costs are likely to render seawater electrolysis competitive within the next decade. This review synthesizes recent advances in materials, system design, optimization strategies, and sustainability metrics, while also highlighting prospective developments in digitalization, circular economy integration, and policy frameworks. The review highlights the potential role of seawater electrolysis in HRES as a foundational component of the emerging global green hydrogen economy.