Cooling Water Demand Reshapes Global Water-Sustainable Hydrogen Production

The stoichiometric water demand for hydrogen production via electrolysis is modest, yet total water use is often dominated by cooling requirements. While the stoichiometric water demand is fixed by the electrochemical reaction, water requirements for cooling electrolysis varies widely depending on local environmental, meteorological and operating parameters. Despite its increasing prominence in sustainable hydrogen production, the significant variability in cooling water requirements for electrolysis across different climates and regions remains poorly quantified. This work aims to address this gap by using a thermodynamic model tailored to the water intense evaporative cooling technology. We contextualized results by incorporating local water scarcity and renewable capacity factors, enabling comprehensive recommendations for sustainable water management. The results indicate that evaporative cooling systems need special considerations in regions where water electrolysis is driven by high PV potentials, with a different picture for wind driven water electrolysis. This highlights the need for region-specific strategies that balance technology choice with local water availability for upcoming hydrogen export regions to ensure resource-efficient hydrogen production. The insights gained are crucial for shaping policies and practices that ensure both environmental and economic sustainability in the hydrogen economy.