Researchers at the Chinese Academy of Sciences have built a system. It uses alkaline water electrolysis to make hydrogen and fresh water at the same time from seawater. The setup captures low-grade waste heat from the hydrogen production process to drive seawater distillation. This approach aims to fix the long-standing problem of salt accumulation damaging water electrolyzers during direct splitting.
Published in Nature Energy by Shang Jiang, Peixin Zhu, and their peers, the work shows a practical way. It bypasses the purified water limits that usually restrict large-scale electrolytic hydrogen generation.
Water Electrolyzers and Seawater Challenges
Water electrolyzers are devices that use electricity to split water into hydrogen and oxygen. Powered by solar cells or other renewable energy tech, these systems could help make hydrogen used to make ammonia. Ammonia is then used to make fertilizers and other valuable compounds.
Even so, most water electrolyzers require purified water, while seawater is far more abundant on Earth. Salts in seawater can damage water electrolyzers and interfere with electrolysis. Shang Jiang, Peixin Zhu, and their peers wrote in their paper that hydrogen production from seawater is attractive given its abundance. However, direct seawater electrolysis remains hard to do due to poor stability and low energy efficiency.
Chinese Academy of Sciences Seawater Distillation Coupling
Researchers at the Chinese Academy of Sciences recently made a system that could produce hydrogen from seawater while also desalinating it to make fresh water. To make this work, the approach pairs alkaline water electrolysis with low-temperature desalination.
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In this coupled process, low-grade waste heat from the electrolyzer drives seawater distillation. The system built by Jiang, Zhu, and their peers uses heat released during hydrogen production to remove salt from seawater.
This thermal integration addresses a major issue in clean energy engineering. The seawater removal process yields fresh water that can then feed an electrolyzer to make hydrogen or get set aside for other uses.
Industrial Pilot Performance and Scale-Up
Moving from lab concepts to physical hardware requires proof that equipment can endure real operating conditions over extended periods. To test these operational limits, the team initially built a 20-kilowatt industrial pilot system and tracked its performance for 100 days.
That 20-kilowatt pilot system, shared in a paper published in Nature Energy, ran stably for 100 days. It reliably produced both hydrogen and fresh water. Reported data show the 20-kW industrial pilot system achieved co-productivities of 3.8 Nm3 h−1 H2 and 1.2 kg (2.6 lb) h−1 fresh water. This included stable operation for 100 days.
Testing stability at the 20-kilowatt scale provided a baseline for larger setups. The research team then scaled the hardware up to 250 kilowatts and measured the hydrogen and fresh water output. Shang Jiang et al published a 250-kilowatt system for co-production of hydrogen and fresh water from seawater in Nature Energy (2026).
Scaled-Up System Efficiency Metrics
Moving from a smaller setup to a larger configuration reveals how well the coupled process maintains its performance. When the team scaled the system up to 250 kilowatts, the equipment achieved 48 Nm3 h−1 H2. It also produced 31.6 kg (69.7 lb) h−1 fresh water.
That production output shows gains in how the hardware handles energy. Specifically, the tech showed a 14.4% boost in system electrical efficiency relative to alkaline electrolysis of fresh water alone. Jiang, Zhu, and their peers wrote that scaling up to 250 kW achieved 48 Nm3 h−1 H2 and 31.6 kg (69.7 lb) h−1 fresh water, with a 14.4% boost in system electrical efficiency relative to alkaline electrolysis of fresh water alone. This gain indicates that coupling thermal distillation directly with the electrolyzer captures operational benefits that standard freshwater setups miss.
Techno-Economic Analysis and Future Outlook
Understanding whether a lab setup can move into practical use depends heavily on its financial outlook. To test this, the research team ran a techno-economic analysis of the coupled process. Their findings point to higher profit potential than the traditional tandem process of desalination followed by electrolysis. By avoiding the need for a separate, standalone desalination plant before feeding water to an electrolyzer, the unified design streamlines equipment needs.
The study introduced a promising way to produce hydrogen from seawater without feeding it directly to an electrolyzer. This avoids the salt-induced wear that plagues standard direct systems. Analyses suggest the two-process approach could be more profitable than desalinating seawater before feeding it to a separate electrolyzer. However, that profit advantage remains a projection, as the team has not yet shown the system’s commercial potential.
Looking ahead, several paths remain open for further validation. In the future, the methods could be refined to improve stability or raise the amount of hydrogen and fresh water produced. The new system could be tested in other settings to check its performance and spot any shortcomings. Eventually, the system may help create commercially viable ways to produce hydrogen and fresh water from abundant seawater.
Two-Process Approach and Future Methods
Whether this setup changes how industries source clean fuel depends on how well these projections hold outside the lab. For now, the reported numbers show that capturing waste heat can solve a stubborn engineering hurdle without needing purified water.
Refining these methods in different settings could help determine if the approach can scale into commercial reality. If future tests match the stability recorded during those 100 days, abundant seawater may finally become a practical starting point for making both clean fuel and fresh water.
Frequently Asked Questions
Question: What is the new seawater hydrogen system?
Researchers at the Chinese Academy of Sciences developed a system that produces hydrogen from seawater while desalinating it to produce fresh water. Water electrolyzers are devices that use electricity to split water into hydrogen and oxygen. Most electrolyzers require purified water, even though seawater is abundant on Earth, because salts can damage them and interfere with the process.
Question: How does the system work?
The system couples alkaline water electrolysis with low-temperature desalination. Low-grade waste heat from the electrolyzer drives seawater distillation to generate fresh water for both electrolysis and external use. Heat released during hydrogen production removes salt from the seawater, yielding fresh water that can feed the electrolyzer or be set aside for other uses.
Question: What achievements were reported for the system?
Shang Jiang, Peixin Zhu and their colleagues published a paper in Nature Energy detailing a 20-kilowatt pilot system that operated stably for 100 days. The team then scaled the system up to 250 kilowatts to measure the hydrogen and fresh water produced. A techno-economic analysis of the coupled process indicates higher profitability than the traditional tandem process of desalination followed by electrolysis.
Question: Is the system ready for commercial use?
The study introduced a promising approach. However, the advantage of higher profitability remains a projection because the team has not yet demonstrated the system’s commercial potential. The methods could be refined later to improve stability or increase output, and the system may be tested in other settings to further validate performance.
Source: https://techxplore.com/news/2026-09-scaled-seawater-hydrogen-fresh-higher.html
Acknowledgment of AI
Content developed using AI technology, reviewed to ensure clarity, coherence, and accuracy before publication
