A team of researchers from MIT and Shanghai Jiao-tong University has unveiled a promising solar-powered desalination device. Made from common materials, it effectively treats seawater by avoiding salt deposits.
An innovative design
Fouling is one of the main problems to which the systems of desalination. During the filtration process, salt and other impurities tend to accumulate on the membranes or other surfaces, which requires regular cleaning of parts or even replacement. Wicking materials being the most affected, the authors of the new study, published in the journal Nature Communicationsset out to design a solar device without it.
Designed to float on the surface of a tank filled with salt water, their system includes a perforated layer that allows the formation of a thin layer of water between it and a dark material that absorbs heat and sunlight, which leads to its evaporation and the formation of droplets of condensation on an inclined surface, used to collect drinking water.
With a diameter of 2.5 mm, the holes made allow natural convective circulation: the hotter water above the perforated material (now showing a significantly higher salt concentration) goes back down into the tank, a new layer is sucked in and the cycle begins once more.
Impressive performance
During the experiments carried out, the team claims to have achieved an efficiency of more than 80% in the conversion of solar energy into water vapor, for salt concentrations of up to 20%. After one week of operation, no crystal deposits were detected in the device.
Scalable, the system also has the advantage of being able to be made from common, and therefore affordable, materials. According to the authors of the study, a desalination device with a collection surface of only 1m² would cost less than 4 euros and would cover the daily water needs of a family.
« Such a system, if perfected, might contribute to the supply of drinking water to isolated or developing regions, and areas hit by natural disasters. “, conclude the scientists.
