Brackish groundwater is a major potential source of drinking water in underserved areas of the world, but desalinating it affordably is a challenge. A new system developed by mechanical engineering professor Amos Winter, Jon Bessette, SM ’22, and staff engineer Shane Pratt manages to do the job entirely on solar energy, with no need for batteries or grid power.
The system is a variation of a previous design based on electrodialysis, which uses an electric field to draw out salt ions as water is pumped through a stack of ion-exchange membranes. That design incorporated both a solar array and a sensor-based control system that dialed the desalting process up and down in response to the amount of sunlight available, but it made the necessary calculations only every three minutes.
“In that time, a cloud could literally come by and block the sun,” Winter says. So backup batteries were still needed.
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