Fresh water is essential for all life on Earth, but water shortages due to climate change, pollution and increasing human demand make that resource increasingly difficult to obtain. Water scarcity affects more than two billion people around the world. According to UNICEFthat number could grow to half of the world’s population by 2025. Nearly half of the 204 U.S. freshwater basins are projected to be shorted monthly by 2071, According to a 2019 study.
There is, of course, a huge source of water that covers 70% of the planet’s surface: the ocean. Through a filtration process known as desalination, unusable seawater is converted to fresh water. This is a method that has been used primarily in the Middle East, but is also increasing in water-stressed areas of the United States, particularly California.
A major problem faced by desalination systems is equipment fouling due to salt build-up, which requires equipment components to be cleaned regularly or completely replaced if damaged. In pursuit of a solution, researchers at MIT and Shanghai Jiaotong University in China have developed a solar-powered desalination device that avoids salt accumulation and can provide drinking water continuously. for a family for only $4.
In a new newspaper published year Nature Communications On Monday, researchers described their new invention: an inexpensive, solar-powered floating desalination device that harnesses a natural phenomenon called convection, which is the tendency of liquids to flow. (and gas) rises to the top when heated and sinks when cooled.
While most desalination systems rely on a wick to draw salt and other impurities out of the water through a device, the researchers have instead developed a layered wickless system. The bottom layer is punched with small holes and draws water towards the top, this layer is made of a dark material that is able to absorb sunlight. The water at the surface is warmed by the sun’s rays, evaporates, and condenses on the surface into drinkable water. The salt left after the water evaporates flows down to the bottom layer through small holes.
Evelyn Wang, a mechanical engineer at MIT and co-author of the new study, said in a statement that this perforated layer makes convection possible, by allowing “natural convective circulation between the warmer water above and the cooler water below”.
The researcher’s experimental apparatus operated for a week with no signs of salt accumulation. The device also performed well and stably when the researchers ran it under conditions that simulated ocean or lake waves.
So far, this is just a rudimentary proof of concept, but the researchers hope to develop their device into something that can be mass-produced and used by individuals and families. , especially for those living in remote communities. These devices can also provide clean water during disaster relief efforts.
The team also suggest that the device’s solar power – proven to be 80 per cent efficient at converting solar energy into steam – has the potential to provide concentrated steam that can be used to sterilization of medical instruments in rural areas.
“I think a real opportunity is the developing world,” says Wang. “I think that’s where the short-term impact is most likely, because of the simplicity of the design. [But] if we really want to get it off the market, we also need to work with the end users, to really be able to apply the way we designed it so that they’re ready to use it. ”