Chinese researchers have developed a solar-powered desalination system that converts seawater into drinking water without requiring external electricity, marking a potential breakthrough in efforts to provide affordable freshwater in water-scarce regions.
South China Morning Post reported the technology, developed by researchers at the Institute of Process Engineering (IPE) under the Chinese Academy of Sciences and Shenzhen University, uses a newly designed three-dimensional photothermal material that captures sunlight and converts it into heat to drive seawater evaporation.
The findings, published in the journal Advanced Materials on 21 June, demonstrated that the prototype operated continuously for a year without external utility energy while maintaining stable performance.
Laboratory tests showed the material achieved a solar absorption rate of 90.2 per cent and reduced the energy required to evaporate an equivalent volume of seawater by 45.7 per cent compared with conventional approaches.
Researchers said the innovation overcomes longstanding challenges associated with solar desalination, including the tendency of nanoparticles to clump together and the degradation of polymer materials after prolonged exposure to sunlight.
To address these issues, the team designed hollow nanoparticles that were interconnected using polymer chains, creating a durable three-dimensional "nanoforest" structure that remained stable under harsh marine conditions.
During durability tests, the material was immersed in seawater and continuously stirred for 30 days, with microscopic analysis showing virtually no particle detachment.
Successful field trial
The researchers also built a 0.75-square-metre outdoor demonstration system in which solar panels powered a fan that directed water vapour into a condensation unit.
Using only natural sunlight, the system produced more than 20 litres of freshwater a day, enough to meet the basic daily drinking requirements of around 10 people.
According to the researchers, the purified water met World Health Organization drinking water standards.
The freshwater was also used to irrigate a five-square-metre test plot where spinach, maize and Chinese cabbage completed full growth cycles.
Based on projections over two years of operation, the researchers estimated that the cost of producing freshwater would fall below that of bottled water, with costs expected to decline further as the technology is scaled up.
The team said it is now working to improve condensation efficiency and reduce manufacturing costs, with the aim of deploying the technology in water-scarce coastal regions, islands and remote communities.
