China develops solar device that turns seawater into freshwater

Beijing: A team of materials scientists in China has developed a solar-powered device that can produce freshwater from seawater at a cost lower than bottled water.

Researchers from the Beijing-based Institute of Process Engineering at the Chinese Academy of Sciences and Shenzhen University created a weave of nanomaterials and organic polymers that is both durable and highly reflective.

The device absorbs 90.2% of incoming sunlight and uses it to evaporate water with 47.5% less energy than conventional methods. In a year-long test, it produced 5.3 gallons of WHO-grade drinking water per day and was used to irrigate 50 square feet of bok choy, beans, and corn.

The scientists said that at scale the system could produce drinking water for less than the cost of a bottled water plant after two years of use.

The breakthrough addresses a long-standing problem with solar evaporation. Previous attempts failed because ultrafine solar-absorbing powders clumped and polymers cracked in harsh coastal conditions. Taking inspiration from a shirt button, the team built nanoparticle spheres that could be threaded together with polymer like yarn. The resulting structure of billions of microspheres proved robust and durable, even in simulated squally coastline conditions. The spheres also reflect light between each other, boosting solar-thermal capacity.

For decades, seawater desalination has relied on energy-intensive membrane or reverse osmosis processes. That has limited the technology mostly to energy-rich countries like Saudi Arabia, which operates hundreds of plants along the Persian Gulf shoreline.

“The team is now working to improve condensation efficiency and reduce system costs, with the aim of scaling up the technology for use in water-scarce coastal areas, islands and remote regions,” SCMP reported.

Researchers say the technology could offer a new option for arid regions struggling with drinking water shortages.