A research team at the Dalian Institute of Chemical Physics (DICP), part of the Chinese Academy of Sciences, has published a paper in the journal Nature Energy describing a demonstration seawater-utilization device rated at 250 kilowatts. The system, named "Seawater to Hydrogen and Fresh Water" (STHW), can simultaneously produce high-purity hydrogen gas and fresh water from the same unit, offering a new technical pathway for addressing both clean energy production and water scarcity. The paper, titled "A 250-kilowatt system for co-production of hydrogen and fresh water from seawater," was published on September 15, 2026, led by DICP researcher Deng Dehui and associate researcher Liu Yanting; the underlying technology had previously been filed for patent protection in China, Japan and Russia.

Water electrolysis is viewed as a key technology for developing the green hydrogen industry, but conventional alkaline electrolyzers typically require large volumes of pure or ultrapure water as feedstock. In many coastal areas, islands and industrial zones that already face tight fresh-water supplies, this creates a real conflict between scaling up green hydrogen production and other demands on fresh water. To get around this bottleneck, teams at universities including Sichuan University and Shenzhen University have in recent years tried electrolyzing seawater directly, skipping desalination altogether; but chloride ions in seawater corrode electrodes, while calcium and magnesium ions form scale that clogs flow channels on the electrode surface, making long-term stable operation a widely acknowledged technical challenge in the field.

The DICP team chose a different technical route: rather than trying to make the electrolyzer "digest" seawater directly, it focused on energy that is already wasted during electrolysis. The team noted that commercial alkaline electrolyzers typically operate at 80 to 90 degrees Celsius, and that around 30 percent of the input electricity is not converted into hydrogen but is instead lost as low-grade waste heat. The team instead used that otherwise-wasted heat to drive a low-temperature vacuum distillation unit: under vacuum, seawater's boiling point drops to roughly 40 to 50 degrees Celsius, so the waste heat alone is enough to keep the seawater evaporating, and the vapor then condenses into fresh water. That fresh water is fed back into the electrolyzer itself as feedstock, with any surplus available for other uses. The whole system needs only seawater as input, requires no separate desalination plant, produces no untreated brine discharge, and avoids the electrode corrosion and scaling problems that come with direct seawater electrolysis.

At the 250-kilowatt demonstration scale, the system produces 48 standard cubic meters of hydrogen per hour, at a purity of up to 99.9999 percent, while co-producing about 31.6 kilograms of fresh water per hour. Compared with conventional alkaline electrolysis using pure water alone, the system's overall electrical efficiency improved by 14.4 percent. The 250-kilowatt unit was not built in one step; it is a scaled-up version of an earlier 20-kilowatt pilot unit, which produced 3.8 standard cubic meters of hydrogen and 1.2 kilograms of fresh water per hour and ran stably for more than 100 days. After scaling up to 250 kilowatts, the research team also put the device through 40 days of daily start-stop cycling to test its stability and reliability under conditions approximating industrial operation.

A techno-economic analysis in the paper found that this integrated approach — coupling hydrogen electrolysis with seawater desalination within a single unit — is more cost-effective than the conventional sequential process of desalinating first and then electrolyzing, which requires building separate desalination and electrolysis plants with higher infrastructure and operating costs. The research team said the finding offers a reference point for the future commercialization path of seawater-resource technologies. Some overseas media reports have noted that the concentrated brine left over after electrolysis could, in theory, be processed in further stages to recover resources such as salt, uranium and bromine, though this has not yet been confirmed in the paper's abstract and would require further research to verify.

This result is one of the latest in a wave of Chinese projects on seawater-resource utilization in recent years, though different teams have taken different technical routes. An earlier study published in Nature by teams from Sichuan University and Shenzhen University took another approach: they designed a membrane-based electrolyzer with a self-breathing waterproof membrane and a self-humidifying electrolyte, through which moisture from seawater migrates spontaneously into the electrolyte via the membrane, eliminating the need for a separate desalination step. That team's demonstration system ran continuously for 133 days in real seawater at Shenzhen Bay, collecting more than a million liters of hydrogen with no significant corrosion observed in the electrochemical cells; off the coast of Fujian, a floating electrolysis platform powered by a 10-megawatt offshore wind turbine also ran continuously for 10 days, with Faradaic efficiency near 100 percent and seawater ion rejection maintained above 99.99 percent.

Another notable project is based in Rizhao, Shandong province. Led by Chinese Academy of Sciences academician Tang Bo, the Laoshan Laboratory, working with the Rizhao municipal government, China General Nuclear Power Group and Shandong Normal University, developed a thermally-coupled system for direct seawater electrolysis that co-produces hydrogen and so-called "strategic elements." In December 2025, a 110-kilowatt-class prototype of the device passed review, producing 22 standard cubic meters of high-purity hydrogen per hour at full load, with a DC power consumption of about 4.2 kilowatt-hours per standard cubic meter of hydrogen, and ran stably for more than 500 hours. On September 28, 2026, an upgraded version of the device, at a pilot base in Rizhao, ran stably for more than 1,000 hours, producing 30 standard cubic meters of high-purity hydrogen per hour at no less than 99.999 percent purity, with the co-produced strategic-element product reaching 99.8 percent purity; by the project's estimate, the device can process about 800 tonnes of seawater a year, yielding 260,000 standard cubic meters of high-purity hydrogen annually. The project team also gave cost estimates at different electricity prices: at 0.55 yuan per kilowatt-hour, the all-in cost of seawater-based hydrogen comes to about 22.21 yuan per kilogram; at 0.40 yuan it falls to 12.99 yuan; and at 0.35 yuan it falls further to 9.92 yuan.

Separately, the "Oriental Hydrogen Island" project built by China Petrochemical Corporation (Sinopec) at its Qingdao refinery uses electricity from a nearby floating photovoltaic plant to directly electrolyze pre-treated seawater, producing about 20 standard cubic meters of green hydrogen per hour; as of earlier reporting it had accumulated more than 1,000 hours of operation, and has been described as China's first factory-based seawater hydrogen production research project. These various projects take different technical routes — some focus on desalination-free direct electrolysis, some co-produce minerals and rare elements alongside hydrogen, and others, like the DICP team's device, turn electrolysis waste heat into fresh water — but all point toward the same industrial goal: giving seawater a bigger role in clean energy production.

Globally, water scarcity and the energy transition are challenges widely shared by coastal and arid regions, and the two problems often reinforce each other: scaling up green hydrogen requires large amounts of fresh water, while desalinating seawater itself consumes energy. The DICP team's device offers one way to ease that tension — by reusing the low-grade waste heat that is otherwise wasted during hydrogen electrolysis, it may be possible to scale up green hydrogen production without increasing fresh water consumption, or even while producing fresh water as a byproduct. The research team said it will continue to work on scaling up the equipment further and moving toward industrial application, and that the paper's techno-economic analysis will also serve as a reference for future engineering design. For a country like China, with its long coastline and rapidly growing offshore wind and solar capacity, a compact unit that can draw on nearby seawater to produce both hydrogen and fresh water at once — whether deployed on an island, in a port industrial park, or at a coastal refining base — could prove more cost-effective than building separate desalination and electrolysis plants.