UWaterloo team says new portable solar desalination device shows high efficiency 

As a sustainable solution to global water scarcity, University of Waterloo researchers are sharing their creation of a device that uses solar power to desalinate seawater with five times the efficiency of current desalination techniques. 

Developed in UWaterloo’s Department of Chemical Engineering, the device mimics the natural water cycle, where water evaporates and condenses, preventing salt accumulation that typically hampers most desalination systems, the researchers said. Made of nickel foam coated with a conductive polymer and thermoresponsive pollen particles, the researchers explain that their portable device can produce 18 to 22 litres of fresh water per square metre per day. 

“Our inspiration comes from observing how nature sustains itself and the way water evaporates and condenses in the environment,” announced UWaterloo researcher Dr. Michael Tam, in a statement, referring to how the device mirrors trees transporting water from roots to leaves. 

Led by Tam and fellow researcher Dr. Yuning Li, the team’s device heats salt water with solar energy, causing it to evaporate and then condense as fresh water in a closed cycle. 

“This process avoids the maintenance issues common in traditional desalination, which require frequent cleaning due to salt buildup,” states an announcement from UWaterloo. “The device can continuously produce fresh water without interruptions and achieves remarkable efficiency, converting 93% of sunlight into usable energy — five times better than existing technologies.”

As the water evaporates, the remaining salt moves to the bottom layer of the device, like a backwash system in a swimming pool, which prevents any potential water blockage and ensures a continuous operation, according to the researchers. 

A study of the new technology was published over the summer in Nature, which notes that recent advancements in solar evaporators have been driven by the development of materials with high photothermal efficiency. These include metal nanoparticles, carbonaceous materials, semiconductors, and polymers.

The UWaterloo team, which includes PhD students Eva Wang and Weinan Zhao, plan to build a prototype of their device that can be deployed at sea to test the technology on a larger scale.