Chinese system produces hydrogen and fresh water from seawater
A research team demonstrated a 250-kilowatt installation in a peer-reviewed study, but commercial application has yet to be shown.
Researchers at the Dalian Institute of Chemical Physics have built a system that produces hydrogen and fresh water from seawater. The results were published in Nature Energy and represent a technical demonstration, not proof that large-scale application is already commercially viable.
The research team combined alkaline water electrolysis with a low-temperature method for desalinating seawater. Waste heat from the electrolysis process is used to distil seawater. The fresh water produced can then be reused for electrolysis and partly made available for other uses.
In a 20-kilowatt installation, the team produced 3.8 cubic metres of hydrogen and 1.2 kilograms of fresh water per hour, according to the publication. The installation operated stably for more than 100 days in that trial. It was subsequently scaled up to 250 kilowatts.
The larger installation produced 48 cubic metres of hydrogen and 31.6 kilograms of fresh water per hour. The researchers report a 14.4 per cent improvement in electrical efficiency compared with conventional alkaline electrolysis using fresh water. That figure applies to the comparison they chose and should not be read as a general efficiency gain for all electrolysers.
Direct electrolysis of seawater is technically difficult because salts can cause unwanted side reactions and damage electrodes and membranes. The Chinese system seeks to circumvent this problem by desalinating the water first. The approach therefore requires additional equipment, but according to the researchers it makes use of heat that would otherwise be lost.
The researchers see potential for later recovering salts, bromine and uranium from the concentrated residual stream. According to the publication, the installation did not demonstrate commercial uranium production. This is a possible next step, not a demonstrated output of the trial.
The research has been published in a peer-reviewed journal, but no independent replication of this system is yet known. Costs, maintenance, the effects of prolonged exposure to seawater and the treatment of concentrated residual streams also remain important uncertainties. The results are therefore primarily relevant as a technical demonstration for hydrogen production in areas where seawater and waste heat are available.
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The technical operation and production figures cited appear in Nature Energy and the explanation by the Chinese Academy of Sciences. The text clearly distinguishes between demonstrated production and possible future uranium recovery.
- confirmed The research was published in Nature Energy. — The publication gives the date and peer-review information. source
- confirmed A 20-kilowatt installation produced 3.8 cubic metres of hydrogen and 1.2 kilograms of fresh water per hour. — Mentioned by the Chinese Academy of Sciences. source
- confirmed A 250-kilowatt installation produced 48 cubic metres of hydrogen and 31.6 kilograms of fresh water per hour. — Mentioned in the research description. source
- confirmed Uranium recovery was not demonstrated in the trial. — The source mentions uranium recovery as a possible application of concentrated brine, not as a measured product of the installation. source
Editor's note
The installation and measured values come from a peer-reviewed publication and an explanation by the Chinese Academy of Sciences. Uranium recovery was mentioned only as a possible next step and was not demonstrated in this trial.Sources
- A 250-kilowatt system for co-production of hydrogen and fresh water from seawater — Nature Energy
- New Strategy Enables Co-production of Hydrogen and Fresh Water from Seawater — Chinese Academy of Sciences
More on this in Dutch media
- NOS — „waterstof zeewater”
- Het Parool — „waterstof zeewater”
- Trouw — „waterstof zeewater”