Rizhao Plant Uses Industrial Waste Heat to Turn Seawater Into Low Cost Water and Green Hydrogen

One seawater supply, three useful products

A compact facility in Rizhao, a coastal city in China's Shandong province, is turning seawater and industrial waste heat into fresh water, hydrogen and concentrated brine for chemical production. As of December 8, 2025, project operators said the installation had run continuously for more than three weeks, an early milestone for a system that combines water treatment with energy production.

The operators put the cost of fresh water at about two yuan per cubic meter, roughly 28 US cents. That is below typical municipal tap water rates in many cities. The plant also produces hydrogen of high purity and retains mineral rich brine that can be sold to marine chemical producers.

The reported annual figures are about 800 tonnes of seawater processed, 450 cubic meters of ultra pure water, 192,000 standard cubic meters of green hydrogen and roughly 350 tonnes of concentrated brine. The water is intended for uses ranging from industrial cooling to household supply.

Hydrogen production reportedly consumes about 4.2 kilowatt hours of electricity per standard cubic meter. The central attraction is the combination of that process with water production driven by heat from nearby steel and petrochemical plants. Such heat would normally escape into the air or ocean.

Rizhao brings three potential sources of income together at one site: water, hydrogen and chemical feedstock. Its longer commercial test will be whether the equipment can maintain these outputs reliably while keeping maintenance, electricity and financing costs manageable.

How waste heat helps separate water from salt

The Rizhao facility places fresh water production beside industries that generate steady supplies of heat at relatively low temperatures. That heat powers a separation stage that turns seawater into very clean water without requiring high thermal thresholds.

Membrane distillation and humidification followed by dehumidification are among the techniques suited to this kind of heat supply. Membrane distillation uses a membrane during water separation. Humidification and dehumidification move water through an evaporation and condensation cycle. Both approaches can make use of heat that is too cool for many other industrial purposes.

Part of the resulting fresh water goes to users, while another part feeds an electrolyzer, a device that uses electricity to split water into hydrogen and oxygen. The remaining concentrated brine can supply chemical production, including bromine, magnesium salts and industrial salt.

Steel mills and refineries release large amounts of heat at medium and low temperatures. Recovering it for desalination, the removal of salt from seawater, reduces the additional electricity needed to produce fresh water. Coastal industrial parks offer a useful combination: abundant seawater, abundant waste heat and a continuing need for cooling.

Locating desalination and electrolysis beside those heat sources can lower operating costs and the carbon intensity of production. It also allows industrial users to draw less water from municipal supplies, easing pressure on local rivers and aquifers, the underground layers that hold groundwater.

What the hydrogen energy figure means

The reported electricity requirement of 4.2 kilowatt hours per standard cubic meter becomes easier to compare with other hydrogen projects when expressed per kilogram. A standard cubic meter measures gas volume under reference conditions and contains about one ninth of a kilogram of hydrogen.

On that basis, Rizhao's figure is approximately 47 kilowatt hours per kilogram. This falls within the operating range of modern alkaline and proton exchange membrane electrolyzers, two established types of equipment for splitting water with electricity.

The innovation lies in the arrangement around the electrolyzer: a seawater treatment line supplied with inexpensive industrial waste heat. That combination reduces water costs and freshwater demand while producing the clean feedwater that electrolysis equipment needs.

The electricity supply still determines whether the hydrogen can be called green. Low carbon electricity is needed for that description. Waste heat makes the thermal part of water production cheaper, but the electrolyzer continues to need substantial electrical power.

At approximately 47 kilowatt hours per kilogram, electricity costing three to five US cents per kilowatt hour would produce a power bill of about $1.40 to $2.35 per kilogram of hydrogen. Equipment, maintenance and financing add to that amount, and their costs vary widely.

Two ways to make hydrogen from seawater

Rizhao appears to follow a route in which seawater is desalinated first and the cleaned water then enters a conventional electrolyzer. Its distinguishing feature is the use of nearby waste heat for water production instead of relying on large electric pumps and high pressure reverse osmosis, which forces water through membranes to remove salt.

Direct seawater electrolysis takes another route. Researchers are developing systems that use seawater without a separate desalination stage, or clean the water sufficiently as part of the process. This approach is especially attractive offshore, where wind farms and platforms could make hydrogen at sea before sending it ashore by pipeline or ship.

Seawater's chemistry makes that difficult. Chloride, sulfate and organic matter can interfere with equipment. In standard cells, reactions at the anode can favor chlorine production, causing corrosion and generating an unwanted chemical. Sand, the buildup of living organisms known as biofouling, and mineral deposits known as scaling can also shorten equipment life.

Research teams are testing catalysts that resist chloride attack, porous separators that block ions involved in unwanted reactions, and designs that keep chlorine away from the reaction zone. A floating demonstration off the Chinese coast has already shown that a system using membranes can operate in rough seas by isolating a clean water layer for electrolysis while drawing its feed from the ocean.

Offshore and remote wind sites may favor these approaches because space and maintenance access are limited. Coastal industrial parks may prefer desalination followed by electrolysis because they have waste heat and nearby customers for both water and hydrogen. Laboratory and pilot work continues on catalysts that resist corrosion, new membranes and concepts that operate without membranes.

How three product streams affect the business case

Fresh water at two yuan per cubic meter is the project's most immediately understandable price claim. The reported cost is below many urban tap water tariffs, while the level of purification could save industrial customers from carrying out some additional treatment themselves.

Clean water also protects electrolyzers. Lowering its cost can improve the economics of hydrogen production in provinces where water is scarce. Producing water and hydrogen together spreads investment costs across two products, while income from chemicals made using the brine can offset part of the operating bill.

Rizhao remains a small installation, but the arrangement offers a possible model for China's coastal industrial corridors. Steel clusters in Shandong, Hebei and Jiangsu are potential locations because they have plentiful waste heat and could accommodate larger equipment.

The three product streams could also help the business cope with changing prices. Income from water and chemical feedstock may cushion fluctuations in hydrogen revenue. For lenders and investors, the appeal will depend on dependable operation and demand for each product.

Power links could support larger plants

China's electricity network is improving access to renewable generation for industrial customers in the east. A corridor using ultra high voltage transmission links large wind and solar fields in western provinces with eastern centers of electricity demand.

New lines connect additional capacity in Gansu to the grid supplying Shandong. Access to steady renewable electricity could allow a larger Rizhao operation to expand its electrolyzers while keeping hydrogen production low in carbon emissions.

The plant has two different energy needs: heat for seawater treatment and electricity for electrolysis. Waste heat supplies the thermal side of the process, while renewable power can support the electrical load, including during periods when waste heat alone cannot meet the site's energy needs.

Larger equipment would need to fit both supplies. The value of the coastal model comes from putting seawater, industrial heat, electricity and customers close enough together to make their connections practical.

Saving freshwater while managing the coast

Producing one kilogram of hydrogen typically requires about nine liters of clean water. That demand becomes consequential when production grows in places where cities, farms and industries already compete for limited supplies.

Expectations for new hydrogen demand point to a need for billions of cubic meters of fresh water within the next decade. Seawater and wastewater offer alternatives that could reduce pressure on scarce inland supplies.

Research indicates that combining desalination with electrolysis and recovering waste heat from fuel cells and electrolyzers can reduce the total energy bill by a few percent. Using coastal water and heat that would otherwise be discarded also leaves more inland water available for farming and cities.

Brine management remains an environmental requirement. Concentrated brine can harm marine ecosystems if it is released without care. Selling it for chemical production, as envisaged in Rizhao, reduces the need to discharge it back into the ocean.

Seawater intakes also require careful design. Drawing water at low velocities through fine screens, and locating intakes where fish and larvae are less abundant, can reduce harm to marine life. These measures matter for permits and community support as more industrial parks consider combining desalination with hydrogen production.

Manufacturing and research build around hydrogen

China's growing hydrogen manufacturing base and network of partners provide a wider setting for projects such as Rizhao. In Tianjin, a major electrolyzer factory now under the full control of a European firm supplies hundreds of megawatts of alkaline modules each year.

The factory has upgraded automation and quality systems and has supplied equipment to some of the largest hydrogen projects already operating. Full control is intended to support faster design changes, tighter logistics and stronger quality assurance for international orders.

Jarle Dragvik, chief executive of HydrogenPro, described the change as a way to align production capacity with demand from very large projects:

It is about streamlining operations and locking in a cost efficient setup ready for large scale projects.

In Shanghai, a global water and energy developer has opened an innovation center to work with universities and laboratories on photovoltaics, wind, energy storage, green hydrogen and seawater desalination. Photovoltaics are the solar technologies that convert sunlight into electricity.

These manufacturing and research efforts connect technologies that an integrated project needs: equipment to make hydrogen, systems to produce clean water, renewable electricity and storage. They also provide a route for design improvements to move from laboratories into operating installations.

Chinese projects extend to Egypt and Saudi Arabia

Chinese companies are also taking hydrogen expertise abroad. One is building a green hydrogen project in Egypt linked to wind and solar generation, with ammonia exports as its target. Another is working with partners in Saudi Arabia to design a giant plant that converts hydrogen into ammonia.

Those projects show the international reach of a supply chain providing equipment, services and operating knowledge. Domestic manufacturing capacity and overseas partnerships are developing alongside coastal experiments such as Rizhao.

The common task is to connect electricity generation, water supply and hydrogen production with a market for the resulting products. Rizhao adds a local industrial heat source and a brine outlet to that arrangement, while the projects in Egypt and Saudi Arabia focus on hydrogen linked to ammonia production.

Longer operation is the next test

More than three weeks of continuous operation is a useful early reliability milestone. Engineers still need longer running periods to understand how the integrated equipment performs over time.

Attention will center on fouling of membranes used in heat driven treatment, scaling in pipes, and the stability of electrolyzers that start and stop as waste heat availability changes. More operating hours will help establish maintenance needs and the most suitable operating windows.

The next expansion date was not given. For future installations, the choice between direct seawater electrolysis and desalination followed by electrolysis will depend on local conditions. Offshore sites with wind and wave power may value compact equipment, while industrial coastal sites may favor a separate water treatment stage supplied with plentiful waste heat.

Rizhao's practical contribution is the integration of resources already present along an industrial coast. It turns seawater into useful products, captures heat that would otherwise be lost and reduces reliance on freshwater supplies. Sustained operation and the full cost of producing and selling all three outputs will determine how widely that model can be repeated.

Key Points

• As of December 8, 2025, the Rizhao facility in Shandong had reportedly operated continuously for more than three weeks.
• Operators put fresh water production costs at about two yuan per cubic meter, roughly 28 US cents.
• Reported annual figures include 800 tonnes of seawater processed, 450 cubic meters of ultra pure water, 192,000 standard cubic meters of hydrogen and 350 tonnes of brine.
• Hydrogen electricity use is about 4.2 kilowatt hours per standard cubic meter, or roughly 47 kilowatt hours per kilogram.
• Industrial waste heat supports desalination, while low carbon electricity is still needed to produce green hydrogen.
• Brine sales can reduce ocean discharge, and carefully designed seawater intakes remain necessary to protect marine life.
• Renewable power connections, electrolyzer manufacturing and research partnerships could support larger installations.
• Longer operation will clarify maintenance needs, reliability and the commercial value of combining water, hydrogen and chemical feedstock production.