Published: Sun, April 16, 2017
Science | By Boyd Webster

Solar-Powered Device To Draw Water Out Of Air, Even In Deserts

Solar-Powered Device To Draw Water Out Of Air, Even In Deserts

"This is a major breakthrough in the long-standing challenge of harvesting water from the air at low humidity", says Omar Yaghi from UC Berkeley regarding the new device. MOFs are still in experimental stages, but chemical companies have started scaling them up for commercialization-and right now Wang said she could buy them for about 10 dollars per kilogram (though other MOFs are far more expensive).

Though researchers at Berkeley and MIT have developed a way to extract clean water from thin air, it will take more research and development to bring the prodct to an low-cost enough price that it can be economically distributed to countries around the world and aras where clean water is in short supply.

The resulting harvester uses MOF crystals compressed between a solar absorber and a condenser plate. The team behind the solar harvester, led by UC Berkeley's Omar Yaghi, wanted to develop a solution that could be used even by those living in arid and drought-hit regions without access to electricity. The vapor gets condensed in the form of liquid water and drips inside the collector from where clean water can be obtained.

The system proposed by Yaghi uses sunlight without any additional power source, although water can only be collected throughout the day. It is now a prototype, but has passed tests in real-world conditions. Future versions of the water harvester could use better MOF materials that can collect more water, or the design could be improved to maximize efficiency.

The humidity could be as low as 20% yet this device will work surely and steadily. The average humidity in the Sahara Desert is 25 percent, which means that the MIT solar cube can easily harvest water here. Ensuring we all have enough water for our needs is simpler than we think, but we're going to need to do more. MOFs are materials created by stitching together organic and inorganic metallic units into porous frameworks with extremely high surface areas, Yaghi tells Newsweek in an email interview. "The special property of this material that made all this possible is the fact that it has high affinity to water molecules to pull them out of the air, but does not hold on to them too tightly so that water can be concentrated and released with a slight temperature change".

MOFs have been used for many different applications in the past, including gas storage, dehumidification and the capture of carbon dioxide emissions.

Scientists have developed devices that could pull our water from the desert areas, powered only by sunlight.

But it's conceivable that someday if you're visiting Death Valley, one of the driest places in the United States, you'll be able to wet your whistle with a device based on Wang and Yaghi's concept.

It's not that hard to collect condensation in a humid climate, but squeezing H20 from arid, thin air is another story.

When it comes to the solar-powered device delivering water to places in need of it, Yaghi and Wang are hopeful that succeeding devices' MOFs would be able to absorb a greater percentage of their weight. "It is just a matter of further engineering now", he said. The background image shows individual MOF crystals, which are packed into the water harvester.

Researchers from the two universities, along with a colleague from King Abdulaziz City for Science and Technology in Saudi Arabia, published a paper Thursday in the journal Science.

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