Desalination is becoming increasingly important for coastal and island nations facing growing concerns about water scarcity due to population growth and rising water consumption. According to the UN World Water Development Report 2024, around 2.2 billion people worldwide lack access to clean water, underscoring the pressing need for new technologies to produce fresh water.
Traditional desalination systems rely on energy-intensive membrane filtration, which is prone to salt accumulation that obstructs water flow and requires frequent maintenance. The newly designed system at Waterloo addresses these issues by drawing inspiration from nature, mimicking how trees move water from their roots to leaves.
"Our inspiration comes from observing how nature sustains itself and the way water evaporates and condenses in the environment," said Dr. Michael Tam, a professor in Waterloo's Department of Chemical Engineering.
"The system we've engineered 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."
Powered by solar energy, the device is remarkably efficient, converting about 93% of the sun's energy into usable power - five times more efficient than current desalination technologies. The device can produce approximately 20 liters of fresh water per square meter, meeting the World Health Organization's daily recommendations for basic drinking and hygiene needs.
The Waterloo team, including PhD students Eva Wang and Weinan Zhao, crafted the device from nickel foam coated with a conductive polymer and thermoresponsive pollen particles. This material absorbs sunlight across the solar spectrum and transforms it into heat. Water, distributed in a thin layer across the polymer, heats up and rises through the system in a manner similar to how water moves through tree capillaries. As the water evaporates, the remaining salt is directed to the bottom layer, preventing blockage and maintaining efficiency.
Dr. Yuning Li, also a professor in the Department of Chemical Engineering at Waterloo, contributed to the project by measuring the light-harvesting efficiency of the device using a solar tester.
"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," Li said. "This technology offers a sustainable solution to the emerging water crisis."
Next, the team plans to develop a prototype that can be tested at sea to evaluate the device's performance on a larger scale.
"If the test is proven successful, the technology can sustainably supply fresh water to coastal communities and advance UN Sustainable Development goals three, six, 10 and 12," Tam said.
Research Report:Thermo-adaptive interfacial solar evaporation enhanced by dynamic water gating
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