Potable drinking water shortages have been plaguing many parts of the globe. As a response, researchers are exploring desalination techniques as a possible solution; however, it still has some humps to straighten out. A novel design for a solar-powered desalination device that also prevents the build-up of salt while efficiently making drinkable water for a cheap price tag has been unveiled.
For a small price of four dollars, researchers from MIT have built a desalination device that can efficiently provide a family's daily drinking water.
Complications of Desalination Systems
One of the main complications that desalination systems face today is fouling. As the device filters salt and many other impurities out of the water, they build up on the device's membrane and other surfaces. This contributes to the hefty price that often accompanies such systems. In addition, it forces parts to be regularly cleaned, or in worst cases, replaced. The wicking materials of the device are the most commonly fouled parts.
As for the novel solar-powered desalination device, scientists from MIT and researchers from Shanghai Jiao Tong University designed a wick-free solar desalination device.
The device, designed to float on the surface of saltwater bodies, is composed of multiple layers. A material with perforations of 2.5mm draws water from the reservoir at the bottom of the device forms a thin layer of water on the device's surface. With the aid of a dark material that can absorb heat from sunlight, the thin layer of water is then heated until it evaporates; hence it can be condensed onto a sloped surface for later collection of pure water.
The salt stays with the remaining water, and this is where the ingenious new idea of the engineering team kicks in. The holes in the device's perforated material are the right size to allow natural convective circulation. The warmer water at the surface of the material that has become denser with salt- is drawn back into the colder body of the reservoir below. A new layer of water is drawn up back to the top part of the material, and the cycle continues.
Viability of a $4 Solar-Powered Desalination Device
In a study published in the journal Nature Communications, titled "Highly efficient and salt rejecting solar evaporation via a wick-free confined water layer," they demonstrated how in tests, the device's technique achieved more than 80% efficiency in converting energy from the sun into water vapor. Researchers note that the findings were the same even when the starting water contained salt concentrations of up to 20% by weight. No salt crystals were observed in the device after one week of operation.
More importantly, the novel system is made out of everyday materials; hence it is scalable and inexpensive to produce and distribute. The team of engineers calculate that the system with a collecting area of 10.8 ft squared could provide enough drinking water for the daily water needs of a family, with materials to build the device only costing roughly four USD, reports NewAtlas.
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