The Tianwan nuclear power plant on the coast of the Yellow Sea in China
Xinhua/Alamy
Chinese scientists have made a groundbreaking advancement in the field of nuclear energy by developing a highly efficient and cost-effective technology for extracting uranium from seawater. This innovation holds great promise for China’s nuclear power ambitions, as the country continues to lead the world in the construction of new nuclear power plants.
The Earth’s oceans contain an estimated 4.5 billion tonnes of uranium, a vast resource that is more than a thousand times greater than conventional mining reserves. However, the challenge lies in the fact that uranium in seawater is extremely dilute. Previous methods of extracting uranium from seawater involved physical adsorption using artificial sponges or polymer materials, as well as electrochemical processes that trap uranium atoms using electric fields.
Building upon these previous techniques, a team led by Shuangyin Wang at Hunan University in China has developed an innovative electrochemical method that is not only more efficient but also more cost-effective for extracting uranium from seawater. Unlike traditional electrochemical systems that only capture uranium at the positive electrode, their device incorporates both positive and negative copper electrodes to attract uranium atoms.
Remarkably, this new approach was able to extract 100 per cent of uranium atoms from a saline solution mimicking seawater within just 40 minutes, outperforming other methods that yield less than 10 per cent extraction. The energy efficiency of the process is also impressive, requiring over 1000 times less energy compared to existing electrochemical methods.
When tested with actual seawater samples from the East China Sea and the South China Sea, the technology demonstrated the ability to extract 100 per cent and 85 per cent of uranium, respectively. The cost of uranium extraction using this method was approximately $83 per kilogram, making it significantly more affordable than previous techniques.
Looking ahead, the researchers envision scaling up their device for industrial applications, potentially revolutionizing the process of uranium extraction from seawater. This advancement is a significant milestone in China’s quest for energy independence and sustainability, particularly in the realm of nuclear power.
As China continues to expand its nuclear energy infrastructure, reducing reliance on imported uranium through seawater extraction could pave the way for a more secure and self-sufficient nuclear industry in the country. With ongoing developments in this field, the future of nuclear power in China looks brighter than ever.
Shuangyin Wang at Hunan University in China and his colleagues have developed an upgraded electrochemical technique that is cheaper and requires less energy than any other for use with seawater. Unlike typical electrochemical systems, which only pull uranium atoms from water at the positive electrode, their device contains two copper electrodes, one positive and one negative, that can both gather uranium.
This approach was able to extract 100 per cent of the uranium atoms from a salty seawater-like solution within 40 minutes. By comparison, some physical adsorption methods extract less than 10 per cent of the available uranium.
The system is “very innovative” and “a significant step forward compared to… existing uranium extraction methods”, says Shengqian Ma at the University of North Texas, who wasn’t involved in the new research.
When tested with small amounts of natural seawater – about 1 litre running through the system at any time – the new method was able to extract 100 per cent of uranium from East China Sea water and 85 per cent from South China Sea water. In the latter case, the researchers also achieved 100 per cent extraction with larger electrodes.
The experiments also showed the energy required was more than 1000-fold less than other electrochemical methods. The whole process cost about $83 per kilogram of extracted uranium. That is twice as cheap as physical adsorption methods, which cost about $205 per kilogram, and four times as cheap as previous electrochemical methods, which cost $360 per kilogram.
Scaling up the size and volume of the new devices – along with potentially stacking or connecting them together – could lead to “industrialisation of uranium extraction from seawater in the future”, the researchers wrote. Given a 58-hour test in 100 litres of seawater, their largest experimental array extracted more than 90 per cent of the available uranium.
One of the most successful previous demonstrations of harvesting uranium from seawater came in the 1990s, when the Japan Atomic Energy Agency extracted a kilogram of the element from the ocean using a physical adsorption method. That set a milestone that has inspired Chinese academic and industry researchers ever since.
In 2019, a Chinese state-owned nuclear company teamed up with research institutes to form the Seawater Uranium Extraction Technology Innovation Alliance. This organisation aims to build a demonstration plant by 2035 and achieve ongoing industrial production by 2050, according to the South China Morning Post.
“From an engineering perspective, there is still a long way to go before implementing this method and any electrochemical-based method for large-scale uranium extraction from seawater,” says Ma.
Half of the nuclear reactor projects currently under construction are in China. The country is on track to surpass the US and the European Union in total installed nuclear power capacity by 2030, according to the International Energy Agency.
But China’s nuclear industry also imports most of the uranium that it uses. So any it can economically extract from seawater will be more than welcome.
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