Researchers Split Untreated Seawater to Produce Green Hydrogen

The breakthrough brings down operational and maintenance cost


An international team of researchers led by the University of Adelaide, Australia said they have successfully split seawater through direct electrolysis without pre-treatment and produced green hydrogen which achieved long-term stability and similar performance to a typical PEM electrolyzer operating in high-purity water.

The researchers said they were able to do this with nearly 100% efficiency, by using a non-precious and cheap catalyst in a commercial electrolyzer.

The team used seawater as a feedstock without the need for any pre-treatment processes like reverse osmosis desolation, purification, or alkanization.

Usually, it is always necessary to treat impure water to a certain level of water purity for conventional electrolyzers including desalination and deionization, which often increases the operation and maintenance cost of the processes.

“Our work provides a solution to directly utilize seawater without pre-treatment systems and alkali addition, which shows similar performance as that of existing metal-based mature pure water electrolyzer,” Associate Professor Yao Zheng, a researcher in the School of Chemical Engineering, said.

The advantage of the discovery is that seawater is an almost infinite resource and is considered a natural feedstock electrolyte. It is even more practical for regions with long coastlines and abundant sunlight.

Zheng said the current electrolyzers are operated with highly purified water electrolytes.

Increased demand for hydrogen can partially or completely replace energy generated by fossil fuels but it also runs the risk of aggravating the existing and increasing crisis of scarcity of freshwater resources.

The researchers concluded that while seawater electrolysis may still be in early development compared with pure water electrolysis because of electrode side reactions, and corrosion arising from the complexities of using seawater, it shows massive potential.

The team said they will work on scaling up the system by using a larger electrolyzer so that it can be used in commercial processes such as hydrogen generation for fuel cells and ammonia synthesis.

Recently, researchers at the École Polytechnique fédérale de Lausanne invented a solar-powered device that is capable of harvesting water from the air for conversion into hydrogen fuel.

In September 2022, a group of researchers at the University of Melbourne developed a way to generate hydrogen directly from the air, eliminating the dependency on freshwater resources and providing a new direction for a carbon-free future.