China turns seawater into green hydrogen

October 05, 2026

Chinese researchers have developed a 250-kilowatt integrated system capable of producing hydrogen and fresh water from seawater while also enabling the recovery of valuable marine resources. According to a new study, the technology improves electricity utilization by 14.4% compared with conventional alkaline water electrolysis.

The project was led by Deng Dehui and Liu Yanting from the Dalian Institute of Chemical Physics at the Chinese Academy of Sciences. Their approach combines hydrogen production with seawater desalination, allowing heat normally wasted during electrolysis to be reused to produce fresh water.

The technology could help address some of the biggest technical and economic obstacles facing seawater-based green hydrogen production.

Solving the challenges of seawater electrolysis

Green hydrogen produced using renewable electricity is increasingly being considered for industries that are difficult to decarbonize. Seawater represents an enormous potential water source, particularly in coastal regions, but using it directly in electrolyzers creates significant challenges.

Chloride ions present in seawater can trigger unwanted chemical reactions at the anode and accelerate electrode corrosion. Meanwhile, calcium and magnesium can accumulate as mineral deposits on the cathode, gradually reducing the electrolyzer's efficiency and lifespan.

An alternative solution is to desalinate seawater before electrolysis. Technologies such as reverse osmosis and thermal distillation can provide the high-quality water needed for hydrogen production.

However, adding a separate desalination stage requires additional equipment and energy, potentially increasing the overall cost of green hydrogen.

The Chinese research team sought to overcome this disadvantage by turning one of electrolysis's main energy losses into a useful resource.

Waste heat used to desalinate seawater

Commercial alkaline electrolyzers typically operate at temperatures of approximately 80–90°C (176–194°F). According to the researchers, around 30% of the electricity supplied to the process can ultimately become low-grade waste heat.

Instead of allowing this energy to dissipate, the new system transfers the heat to an integrated desalination facility.

Waste heat from the electrolyzer feeds a vacuum distillation tower. Because the pressure inside the tower is reduced, seawater can boil and evaporate at temperatures of only 40–50°C (104–122°F).

The resulting water vapor is then condensed to produce fresh water.

According to the Chinese Academy of Sciences, the process generates enough purified water to meet the electrolyzer's requirements while also producing additional fresh water that can be used elsewhere.

This integration reduces the amount of electricity that would otherwise be required for a separate desalination process.

Valuable resources can be recovered from seawater

Hydrogen and fresh water are not the system's only potential outputs.

After desalination, the remaining concentrated seawater contains minerals and other substances that can potentially be extracted and used commercially.

Researchers say the concentrated brine could support the recovery of salt, bromine, uranium and other valuable marine resources, creating additional opportunities to improve the economics of seawater processing.

250-kW hydrogen plant successfully tested

The latest project represents a major scale-up from a 25-kW demonstration system developed by the research team in 2023.

Researchers have now expanded the technology to 250 kW, demonstrating its potential for larger-scale hydrogen production.

The new facility is capable of producing approximately 380,000 standard cubic meters of hydrogen per year, equivalent to roughly 13.4 million standard cubic feet. The hydrogen produced by the system reaches a purity of 99.99%.

At the same time, the facility can generate approximately 256 metric tons of fresh water annually.

During testing, the 250-kW system operated for 40 days under daily start-stop conditions, with researchers reporting no obvious deterioration in its performance.

The results indicate that integrating desalination directly with hydrogen production could offer a practical pathway toward more efficient use of seawater.

Energy efficiency improves by 14.4%

One of the system's most significant advantages is improved energy utilization.

According to the study, recovering waste heat and using it for desalination increased overall electricity utilization by 14.4% compared with traditional alkaline water electrolysis.

The researchers also concluded that the integrated approach could become more economically competitive than conventional systems where seawater is first desalinated separately and then supplied to an electrolyzer.

This could be particularly important for coastal green hydrogen facilities powered by renewable energy.

Green hydrogen costs could fall below current prices

The researchers also evaluated the potential cost of producing hydrogen using different renewable electricity sources.

With onshore wind electricity priced at $0.033 per kilowatt-hour, the estimated hydrogen production cost was approximately $2.10 per kilogram.

When using solar electricity priced at $0.049 per kWh, the estimated production cost increased to around $2.90 per kilogram.

For comparison, the study referenced a current hydrogen selling price of approximately $3.90 per kilogram, suggesting that the integrated system could potentially offer competitive production economics under favorable renewable energy conditions.

Researchers plan further efficiency improvements

The scientists believe there is still considerable room to improve the technology.

Deng said future research will focus on developing more efficient catalysts, recovering a greater proportion of waste heat from electrolyzers and using artificial intelligence to optimize operating parameters.

Further improvements could reduce energy consumption and hydrogen production costs while increasing the amount of fresh water and valuable resources recovered from seawater.

If successfully scaled, the technology could eventually allow coastal renewable energy projects to simultaneously produce green hydrogen, fresh water and valuable marine resources, potentially improving both the sustainability and economics of hydrogen production.I can also prepare the SEO title, meta description, and several title options under 50 characters for this article.