Professors Michael Tam and Yuning Li have designed a solar-powered desalination device capable of utilizing over 93% of solar energy to produce fresh water from the sea via a thermal evaporation process.

This rate is five times higher than that of current technologies, making it a highly efficient solar-driven desalination system. With a production capacity of approximately 20 litres of fresh water per square meter per day, this device offers a sustainable solution to global freshwater scarcity.

Desalination of water is critical for many coastal nations to produce water for consumption and agricultural activities. Rapid population growth and increasing global water consumption by industry contribute to water scarcity.

Current desalination systems pump seawater through membranes to separate salt from water, but this process is energy-intensive and leads to salt accumulation on the devices, which reduces efficiency. Current systems also require frequent backwashing and cannot operate continuously.

Remote video URL

This video shows the salt accumulation in the middle, you can observe the salt gradually dissolving back into the water. The salt completely disappeared within half an hour demonstrating the evaporator’s ability to achieve rapid self-cleaning. That’s the backflow transport mechanism that prevents salt accumulation.

The research group overcame these challenges through biomimicry inspired by the natural water cycle and the way trees transport water from roots to leaves. They have designed a self-cleaning, energy-efficient system that continuously desalinates water without the need for manual intervention or backwashing.

“Our inspiration comes from observing how nature sustains itself, and the way water evaporates and condenses in the environment as well as how trees transport water,” says Tam a University Research Chair and director of the Laboratory for Functional Colloids & Sustainable Nanomaterials. “We’ve engineered a system that induces water to evaporate, transports it to the surface, and condenses it in a closed cycle, effectively preventing the accumulation of salt that reduces the efficiency of the device.”

The research team includes two PhD students Eva Wang and Weinan Zhao. They leveraged nickel foam coated with a conductive polymer in making the device. This material absorbs sunlight across the solar light spectrum, converting solar energy into heat. A thin layer of salt water on the polymer heats up quickly and is transported upward by capillary action, like water naturally travelling through the capillaries in trees. As the water evaporates, the remaining salt is transported back to the bottom layer of the device, like a backwash system in a swimming pool, preventing blockage and ensuring continuous operation.

Li brought his expertise in harvesting solar energy to the project. He used a solar tester to measure the device’s light-harvesting properties.

“This new device is not only efficient but also portable, making it ideal for use in remote regions where access to fresh water is limited,” says Li director of the Printable Electronic Materials Lab. “This technology offers a sustainable solution to the emerging water crisis.”

The next step in this research is to design and build a prototype that can be deployed at sea to test the performance of the technology.

The study is published in the Nature Communications journal.

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