Americans’ access to clean water is projected to become a more important issue in the coming years as drought and shrinking groundwater supplies — influenced to a certain degree by climate change — touch more parts of the U.S.
Engineers at the University of Wisconsin-Madison created a device that could be revolutionary in helping to meet clean water needs. This water vapor condenser is a big deal because it’s cheaper than other clean water production methods, and it is designed to grab water from the air without using an external power source.
“You can’t set out to solve the water problem without addressing energy,” Zongfu Yu, an associate professor of electrical and computer engineering at UW-Madison, said in a news release.
Radiative vapor condensers aren’t a new idea. These dew collectors use special materials that give off heat so their temperature drops below the dew point, prompting condensation to form and be collected. But the water collection devices only work at night because sunlight produces more heat than the materials can give off.
The UW-Madison researchers constructed a small vapor condenser made from a thin film material that is very efficient at releasing thermal radiation. The film is layered over silver, which reflects sunlight. Together the two layers cool the condenser below the dew point to allow for condensation production, even in the hot sun.
Another bonus is that the thin film material is relatively cheap and widely available. Plus, the device does not necessarily need the silver layer to work, further lowering costs. Material cost and availability previously has been a barrier to creating this kind of innovation.
The research team tested this film against other commercially available dew collection materials. They were all placed into box-like condensation chambers that had humidified air pumped in. The researchers’ film was the only material that condensed water vapor in direct sunlight.
The researchers aim to commercialize their innovation through a company they established, Sunny Clean Water. They want to combine it with another passive cooling method — solar vapor generation — so even untreated or saltwater can be vaporized and run through the condenser for purification. Sunlight would be the only energy source.
Eventually, they would like to perfect the technology so water can be efficiently produced directly from the air.
“This experiment was done using some controlled water vapor,” Yu said. “Now, the next step is to pull the water directly out of the air. That’s very, very exciting to us — to get water from the air for free using no energy.”
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