High Spatiotemporal Availability of Hydrogen by Electrolysis of Municipal Reclaimed Water in China

Large-scale electrolytic H₂production requires a stable electricity supply, sustainable water availability, and proximity to the H₂end-user. However, these elements often exhibit spatiotemporal mismatches in China. Reclaimed water, an unconventional water resource generated by municipal wastewater treatment plants, is widely distributed across China. This study conducted a life-cycle assessment of H₂production from reclaimed water in China, focusing on potential capacity, cost, and carbon emissions. The results were compared with those using tap water and seawater. Even when prioritized for ecological and municipal reuse, reclaimed water demonstrated significant H₂production capacity (95.7–213.1 Mt/year between 2021 and 2060), attributable to its proximity to critical resources and H₂markets. This capacity could meet China’s annual H₂demand (33.4–130.9 Mt/year) while achieving provincial self-sufficiency. By contrast, H₂production capacity using tap water and seawater is substantially lower (19.8–79.1 Mt/year). Currently, H₂production from reclaimed water exhibits cost and carbon emissions comparable to those of conventional electrolytic routes. However, advancements in electrolyzer efficiency and grid decarbonization could reduce these metrics to 4.0 ± 0.5 USD/kg H₂and 4.99 ± 0.05 kg CO₂-eq/kg H₂by 2050, making it competitive with fossil-derived H₂(∼4.3 USD/kg H₂) while meeting green H₂threshold (∼4.9 kg CO₂-eq/kg H₂).