Water-energy-hydrogen nexus: Addressing water scarcity in sustainable green hydrogen production

• Strong potential of Green H 2 to drive the transition toward a sustainable future. • Highlighting the high dependency of H2 production on freshwater. • Freshwater scarcity in regions with abundant RES poses a critical challenge. • Sea/brackish water desalination as promising solutions to address water limitations. • Policy makers play a key role in advancing the WEH nexus through R&D strategies. The global transition toward a green economy has intensified the focus on sustainable pathways within the water-energy-hydrogen (WEH) nexus. Green hydrogen is widely recognized as a promising route to decarbonize the energy sector, yet its reliance on high-purity water for electrolysis presents major challenges, particularly in desert and sub-humid regions where water scarcity is already acute. This review critically examines the WEH nexus with emphasis on water supply through seawater and brackish water desalination technologies, including multi-stage flash (MSF), multi-effect distillation (MED), and reverse osmosis (RO). It further analyzes the economic and environmental trade-offs of these approaches, from carbon intensity, brine management, operational costs, and opportunities for renewable energy source (RES) integration. By assessing desalination’s potential to enable sustainable hydrogen production, this review highlights policy frameworks, technological innovations, and material advances required to reconcile water demand with energy transition goals, offering directions for research and future implementation strategies.