In a major breakthrough for the race to produce affordable green hydrogen – a fuel essential for the world’s net-zero goals, scientists from Australia’s University of Adelaide have reported that they have successfully managed to split sea water into oxygen and hydrogen, without pre-treatment to produce green hydrogen.
Green hydrogen is a highly reactive fuel alternative to traditional fossil fuels – is produced through a chemical process known as electrolysis. This process uses an electrical current to separate the hydrogen from the oxygen in the water using renewable sources.
Professors Shizhang Qiao and Yao Zheng from University of Adelaide’s School of Chemical Engineering led an international team that successfully made the breakthrough.
“We have split natural seawater into oxygen and hydrogen with nearly 100 per cent efficiency, to produce green hydrogen by electrolysis, using a non-precious and cheap catalyst in a commercial electrolyser,” said Professor Qiao.
Professor Zheng added, “Current electrolysers are operated with highly purified water electrolyte. Increased demand for hydrogen to partially or totally replace energy generated by fossil fuels will significantly increase scarcity of increasingly limited freshwater resources.”
Reducing green hydrogen production costs
The production of green hydrogen from untreated sea water will be crucial in bringing down the costs for green hydrogen as the treatment of water before electrolysis through the energy intensive desalination process escalates the costs for green hydrogen.
Electrolysis of seawater to produce green hydrogen is still in early development, compared with pure water electrolysis because of electrode side reactions, and corrosion arising from the complexities of using seawater.
“It is always necessary to treat impure water to a level of water purity for conventional electrolysers including desalination and deionization, which increases the operation and maintenance cost of the processes,” noted Zheng. “Our work provides a solution to directly utilise seawater without pre-treatment systems and alkali addition, which shows similar performance as that of existing metal-based mature pure water electrolyser.”
The University of Adelaide team revealed that they are working on scaling up the system by using a larger electrolyser so that it can be used in commercial processes such as hydrogen generation for fuel cells and ammonia synthesis.