Clean drinking water is one of the most urgent needs in many parts of the world.
Now, a team of researchers from UNIST in South Korea has created a solar-powered device that can produce fresh water directly from seawater—without needing any outside electricity.
The new technology could become a lifeline for people living in regions where water is scarce and access to power is limited.
The research, led by Professor Ji-Hyun Jang of the School of Energy and Chemical Engineering, focuses on solving two big challenges in solar desalination: efficiency and salt buildup.
Most solar-powered systems that evaporate seawater struggle over time because salt crystals accumulate on their surfaces, blocking sunlight and slowing down the process.
The UNIST team has designed a system that not only avoids this problem but also works much faster than traditional methods.
At the heart of the device is a simple but clever design: an inverse-L-shaped strip of paper. Like litmus paper, this material naturally absorbs water and carries it upward.
When the seawater reaches the top of the strip, it comes into contact with a special material—La₀.₇Sr₀.₃MnO₃, or LSMO for short. This perovskite-based semiconductor absorbs sunlight and quickly turns the water into vapor.
The L-shape of the design plays an important role. Instead of letting salt build up on the heating surface, the shape drives salt particles toward the edges, where they crystallize and can be collected.
This self-cleaning feature means the device can keep working efficiently for a long time. It also allows the collected salt to be reused, offering an added benefit for industries or communities that harvest salt.
In terms of performance, the results are striking. The device achieved an evaporation rate of 3.40 kilograms per square meter per hour—about 3.4 liters of water—under natural sunlight.
That’s roughly eight to ten times faster than what usually happens when water is left to evaporate on its own.
Even when tested in extremely salty water, with 20% salt content (much higher than seawater’s typical 3.5%), the device continued to operate smoothly for more than two weeks.
Dr. Saurav Chaule, the lead author of the study, explained that this design provides a sustainable way not only to produce freshwater but also to recover salt in an environmentally friendly way.
Professor Jang added that the combination of innovative design and advanced materials has created a cost-effective, electricity-free solution to one of the world’s greatest challenges.
By showing how sunlight alone can be used to reliably produce safe drinking water, this breakthrough could help communities around the globe face the growing crisis of water scarcity with a tool that is both practical and scalable.
Source: KSR.
