Desalination breakthrough uses sun, not electricity, to clean seawater
23rd May 2024
The researchers use a phenomenon called thermodiffusion, a temperature gradient to move salt from the warmer to the colder side to bring about desalination. In this process, water remains in the liquid phase, and no energy is spent turning it into vapor and cooling it back.
In a technology demonstrator, the researchers used a narrow channel for the seawater. They sandwiched it between two plates maintained at different temperatures. The top plate was heated to over 140 Fahrenheit (60 degrees Celsius), while the lower plate was cooled to 68 Fahrenheit (20 degrees Celsius).
The channel was a little over one and a half feet long, and low-salinity water emerged from the top while high-salinity water emerged from its bottom. After a single pass, cooler and saltier water was removed, and warmer and less salty water was put back into the setup.Each pass saw the water’s salinity decrease by three percent, and using multiple cycles, the salinity decreased from 30,000 parts per million to less than 500 ppm.
Interestingly, the heat needed to carry out the process can come directly from sunlight or even waste heat generated during industrial processes.