Sustainable water sourcing is a critical component of electrolysis-based hydrogen production, particularly as the world moves toward decarbonization. Electrolysis requires high-purity water, and securing this resource without exacerbating freshwater scarcity is a key challenge. Three primary strategies—solar-desalination, wastewater reuse, and rainwater harvesting—offer viable pathways to minimize freshwater consumption while supporting large-scale hydrogen production. Each approach has distinct energy and cost implications, especially in arid regions where water scarcity is acute.
Solar-desalination presents a promising solution for coastal or brackish water-rich regions. Desalination traditionally demands significant energy, but coupling it with solar power reduces reliance on fossil fuels. Photovoltaic-powered reverse osmosis or solar-thermal desalination can produce the high-purity water required for electrolysis. For example, a project in Neom, Saudi Arabia, integrates solar-desalination with a gigawatt-scale hydrogen plant, aiming to produce 650 tons of hydrogen per day by 2026. The energy penalty of desalination adds approximately 3-4 kWh per cubic meter of water, but advances in membrane technology and energy recovery systems are lowering this cost.
Wastewater reuse is another sustainable strategy, particularly in urban or industrial settings. Municipal or industrial wastewater can be treated to ultrapure standards using advanced filtration and electrochemical processes. The energy requirement varies based on the initial water quality, but tertiary treatment typically consumes 1-2.5 kWh per cubic meter. A notable example is the Tokyo Metropolitan Government’s initiative to use treated wastewater for hydrogen production in partnership with local industries. By leveraging existing wastewater infrastructure, the project avoids additional strain on freshwater resources while creating a circular water economy.
Rainwater harvesting offers a decentralized and low-energy solution, particularly in regions with seasonal rainfall. Collected rainwater can be purified through sedimentation, filtration, and ion exchange to meet electrolysis standards. While rainfall dependency limits scalability in arid zones, hybrid systems combining rainwater with other sources enhance reliability. In India, a pilot project in Karnataka utilizes rooftop rainwater harvesting to supply a small-scale electrolyzer, demonstrating the feasibility of this approach in water-stressed rural areas.
The energy and cost implications of these strategies vary significantly. Solar-desalination, while effective, requires high upfront capital for solar infrastructure and desalination plants. Wastewater reuse benefits from existing treatment facilities but may need additional polishing steps. Rainwater harvesting is cost-effective but limited by climatic conditions. In arid regions, hybrid systems that combine multiple sources optimize reliability and cost-efficiency.
Technological innovations are further reducing freshwater demands in electrolysis. Direct air electrolysis, an emerging technology, extracts water vapor from the atmosphere, bypassing the need for liquid water sources altogether. Although still in early development, prototypes have demonstrated feasibility in low-humidity environments. Another innovation is the integration of electrolyzers with industrial processes that produce water as a byproduct, such as fossil fuel power plants equipped with carbon capture systems.
Several projects worldwide highlight successful implementations of sustainable water sourcing for hydrogen production. In Australia, the Asian Renewable Energy Hub plans to use desalinated seawater powered by wind and solar for its 26 GW renewable hydrogen facility. In California, the Hyperion Water Reclamation Plant supplies treated wastewater to a nearby electrolyzer, reducing reliance on imported freshwater. These projects underscore the importance of region-specific solutions tailored to local water availability and energy resources.
The scalability of sustainable water sourcing for hydrogen production depends on continued advancements in water treatment, renewable energy integration, and policy support. Governments and industries must collaborate to incentivize water-efficient technologies and develop regulatory frameworks that prioritize resource sustainability. As the hydrogen economy grows, ensuring that water sourcing aligns with environmental and social goals will be paramount.
In conclusion, solar-desalination, wastewater reuse, and rainwater harvesting provide viable pathways to secure water for electrolysis without depleting freshwater reserves. Each method has distinct trade-offs in energy use and cost, but technological innovations and hybrid systems are mitigating these challenges. Real-world projects demonstrate that sustainable water sourcing is not only feasible but also essential for the long-term viability of green hydrogen production. By prioritizing water-smart strategies, the hydrogen industry can achieve its decarbonization goals while safeguarding global water resources.