A new study in Communications Sustainability finds that the total freshwater needed for green hydrogen is often much higher than expected. While electrolysis itself uses about 9 to 10 liters of water per kilogram of hydrogen, evaporative cooling for large-scale electrolyzers can add another 19 to 39 liters per kilogram depending on the local climate. In hot, arid regions where solar power is abundant, cooling water demand can be two to five times the amount used for hydrogen production itself. The research combined climate data with water-stress indices and found that many planned green hydrogen projects are located in areas already facing moderate to severe water scarcity. About 25% of global planned capacity, including major projects like NEOM in Saudi Arabia and Hyphen in Namibia, falls into high-risk zones. The authors suggest that dry cooling or seawater desalination could help, but each option comes with tradeoffs in cost and efficiency. For anyone tracking the real-world viability of green hydrogen, this study is a useful reminder that renewable energy potential and water availability don't always line up. Project developers and policymakers will need to factor in local water constraints early in the planning process, not just carbon metrics.
