- Scientists have successfully converted seawater into hydrogen and oxygen without the need for desalination
- The experiment points the way to an efficient new source of energy from electrolysed seawater
An offshore platform in southeastern China harnessed both wind and solar power to produce hydrogen without the need for desalination. Photo: WEIBIO
A team of Chinese researchers has moved a step closer in the quest for clean, renewable energy by converting seawater into hydrogen and oxygen.
The offshore platform development that harnessed both wind and solar power in the first successful attempt to use seawater without the need for desalination was led by researcher Xie Heping from Shenzhen University and the state-owned Dongfang Electric Corporation.
The platform – dubbed “Dongfu Number One” – is anchored in the waters of southeastern China off the coast of Fujian province and is capable of withstanding high waves and gusts up to force 8 on the Beaufort scale.
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“It successfully completed a 10-day continuous operation during its inaugural run in May, marking a promising start to the prospect of offshore hydrogen production powered by renewable energy,” state news agency Xinhua reported on June 3.
The 63 square metre (678 sq ft) platform combines a hydrogen production system with a stable offshore wind power supply system. By combining the two components, the researchers created an environmentally friendly floating farm that electrolyses seawater into hydrogen without creating undesirable side effects or pollution.
“This demonstration experiment not only validated the device’s anti-interference capacity but also produced valuable data. The project is an exemplary case of transitioning from academic achievement to industrialisation,” the report said.
Xie’s team – the creators of the hydrogen production technology at the core of the platform – first published an article about the process in the peer-reviewed journal Nature in November.
Seawater is complex to work with because of the complexity of its composition. It is full of microorganisms and suspended particles, which often leads to low efficiency for electrolysis while shortening the lifespan of the equipment.
Previous projects – such as those in the Netherlands and Germany – have often relied on first desalinating seawater, then using the freshwater for hydrogen production.
But that approach adds complexity to the process – requiring extensive desalination equipment and large land resources, which increase both the cost of hydrogen production and the difficulty in building a project.
Since the 1970s, scientists have been searching for ways to make hydrogen by electrolysing seawater directly. The solution offered by Xie’s team earned recognition from the Ministry of Science and Technology as one of China’s top 10 scientific advancements in 2022.
Dongfang Electric Corporation, meanwhile, helped to industrialise the production of the technology to ensure a stable supply of offshore wind power. Powered by a 10 megawatt wind turbine and equipped with a 28 kilowatt energy storage system, the floating electrolysis platform maintained hydrogen production with nearly 100 per cent Faraday efficiency for 10 straight days, the researchers said.
Even under those conditions, the performance and energy consumption of the platform remained comparable to laboratory conditions.
After 10 days of operating in seawater, the scientists said the system still maintained an impressive ion rejection rate of more than 99.99 per cent, producing hydrogen that was at least 99.9 pure.
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Moreover, with no need for desalination, the platform offers a cost-effective alternative to current industrial production. The technology costs as little as 11.2 yuan (US$1.57) per kilogram (2.2 pounds) of hydrogen – much less than the current mainstream cost of hydrogen production from natural gas, which ranges from 20 to 24 yuan per kilogram.
Xie said the team would now look to upscale their achievement.
“We have successfully integrated offshore renewable energy and achieved desalination-free electrolysis of seawater in the real and complex ocean. Our team plans to develop a more efficient hydrogen production system that can withstand interference, and promote its industrialisation with global companies,” Xie said.