Researchers from the University of California Berkeley and the Massachusetts Institute of Technology (MIT) have developed a device that uses solar power to pull liters of water from the air—even in arid areas like deserts. The device uses a metal-organic framework (MOF) that can absorb gasses and liquids to condense water vapor in the air into water. Such devices will be important as clean drinking water becomes more scarce.
“There are desert areas around the world with around 20 percent humidity,” where potable water is a pressing need, “but there really hasn’t been a technology available that could fill” that need, co-author and MIT associate professor of mechanical engineering Evelyn Wang told MIT News. The new system, by contrast, is “completely passive — all you need is sunlight,” with no need for an outside energy supply and no moving parts.
“This is a major breakthrough in the long-standing challenge of harvesting water from the air at low humidity,” said Omar Yaghi, another senior author of the paper, who holds the James and Neeltje Tretter chair in chemistry at UC Berkeley and is a faculty scientist at Lawrence Berkeley National Laboratory. “There is no other way to do that right now, except by using extra energy. Your electric dehumidifier at home ‘produces’ very expensive water.”
The researchers published their work in Science. The MOF was developed at UC Berkeley while the device was made at MIT. The device they tested as a proof of concept can absorb only 20 percent of its weight in water.
“We wanted to demonstrate that if you are cut off somewhere in the desert, you could survive because of this device. A person needs about a Coke can of water per day. That is something one could collect in less than an hour with this system,” Yaghi said.
“It’s not just that we made a passive device that sits there collecting water; we have now laid both the experimental and theoretical foundations so that we can screen other MOFs, thousands of which could be made, to find even better materials,” Yaghi said. “There is a lot of potential for scaling up the amount of water that is being harvested. It is just a matter of further engineering now.”
The device the researchers created pulled 2.8 liters (3 quarts) of water from air between 20 percent and 30 percent humidity over 12-hours. The device used one kilogram (2.2 pounds) of the MOF material. It also was tested in real-world conditions on a rooftop at MIT.
“One vision for the future is to have water off-grid, where you have a device at home running on ambient solar for delivering water that satisfies the needs of a household,” said Yaghi. “To me, that will be made possible because of this experiment. I call it personalized water.” The researchers are now working on improving both aspects of the device. The Berkeley team is working to improve the MOFs while the MIT team is working to improve the harvesting system to increase water production.Tweet