Water is among the most important resources on earth; however it is not evenly distributed. While some areas have ample access to drinkable water, others may only have access to undrinkable saltwater.
Michael Tam is a professor of chemical engineering at the University of Waterloo and deputy editor of the American Chemical Society (ACS) Sustainable Resource Management journal. Tam and his team have created a device that addresses this issue by converting saltwater into drinkable water using solar power.
“The research project [focuses on using] the abundant solar energy and developing a device that can harvest solar energy and then evaporate water and capture it for drinking,” Tam said.
The process is based on the process trees use to move water from their roots to their leaves. The team has developed a working prototype. The device was set up on the roof of a building with ample sunlight exposure to demonstrate how the process works.
Tam said the device harvests solar energy and uses it to heat a surface that induces water to flow from the bottom upward and evaporate.
“If you drive around in the fall, you find that, above lakes, you get a lot of fog when the temperature is cool, because water is constantly evaporating from the lake, and then when it encounters a very cold environment that condenses into liquid water,” Tam said.
“Water flows up and evaporates, and then we capture it by condensation,” he said.
When saltwater is desalinated, it leaves behind salt crystals at the bottom of the device. After a few hours, the process usually must be stopped so that the device can be cleaned before the process can start again. “Our device [cleans itself] automatically by designing a temperature control system using some material that responds to temperature and that allows the back-washing and no salt is formed at the bottom,” Tam said.
The current process of desalination pushes salt water through a membrane to filter out the salt, but it requires a lot of power, which is expensive. Tam’s team’s device only requires the energy it can capture from the sun. The current prototype can capture approximately three to five meters of water per meter square per hour. However, the team wants to build a larger version of the device that would be usable in the ocean. “We can envisage a concept where we can build a one-meter square surface, or a device you can put into the ocean and then demonstrate viability in extracting pure water from sea water,” Tam said.
The next steps for the project would be to secure the funding and manpower that would allow the team to build a new version of the device that can be tested in a saltwater environment.
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