Watershed moment: Engineers invent high-yield atmospheric water capture device for arid regions

As a megadrought stresses the water supply throughout the Southwest, revolutionary research out of UNLV is answering this problem with a groundbreaking technology that pulls large amounts of water from the air in low humidities. The research was published Oct. 22 in the journal Proceedings of the National Academy of Sciences (PNAS).

UNLV mechanical engineering professor H. Jeremy Cho leads a team of researchers with a radically different approach to atmospheric water harvesting, or transforming water vapor in the air around us into a usable form. Existing atmospheric water harvesting approaches have low yields and diminishing returns at humidities below 30%.

"This paper really establishes that you can capture water at a very fast rate," said Cho. "We can start to forecast how big of a system we would need to produce a set amount of water. If I have one square meter, which is around three feet by three feet, we can generate about a gallon of water per day in Las Vegas, and up to three times more in humid environments."

This technology and approach has been tested outdoors in Las Vegas, and is effective down to 10% humidity. It directly captures water in a liquid salt solution that is suitable for subsequent processing into drinking water or energy production, enabling new capabilities for arid regions.

A key ingredient in the process is a hydrogel membrane "skin." The inspiration for this material comes from nature -- specifically tree frogs and air plants, which use a similar technique to transport water from ambient air into a liquid for internal storage.

"We took that biological idea and tried to do it in our own way," he said. "There are so many cool things happening in nature -- you just have to look around, learn, and be inspired."

Additionally, the research demonstrates that atmospheric water harvesting can be solar-powered. Thanks to the frequent sunlight experienced in places such as the Las Vegas Valley -- which averages 300 sunny days a year sunlight can provide enough energy to reduce the theoretical and eventual cost for generating water.

"Our water resources are depleting and our planet's climate is changing," said Cho. "To reach sustainability, we have to change our habits. This whole idea seemed like science fiction, but this is possible, and we're actually doing it."

The research is already being put into practical use in the form of WAVR Technologies, Inc. Cho co-founded this UNLV startup, making devices capable of capturing water vapor from the air around us for commercial and individual uses. WAVR is the premiere university business spinoff from the National Science Foundation (NSF) Regional Innovation Engines program aimed at bringing to market technologies that address regional sustainability and climate concerns.