A prototype MOF-based water-collection device is set up for testing on the roof of a building on the MIT campus. (Evelyn Yang, MIT)

Researchers have come up with a new way to extract water from thin air. Literally.

This isn’t the first technology that can turn water vapor in the atmosphere into liquid water that people can drink, but researchers from the Massachusetts Institute of Technology and the University of California, Berkeley, say their approach uses less power and works in drier environments.

The new approach makes use of a substance called a MOF, a metal-organic framework. As the name suggests, these are materials made of metals mixed with organic compounds. Powders made from MOFs are very porous, so researchers have proposed using them to store hydrogen or methane fuels or to capture carbon dioxide.

MIT’s Evelyn Wang and her Berkeley colleague Omar Yaghi decided to try using MOFs to capture water. MOF powders can not only suck up liquid water, they can also absorb water vapor.

And there’s plenty of water vapor in the atmosphere. Even in the driest place on the planet there are tons of water molecules floating overhead.

The researchers built a small prototype water collector that contains a thin layer of MOF powder. The powder absorbs water vapor until it is saturated.

“Once you achieve that maximum amount,” Wang says, “you apply some type of heat to the system to release that water.”

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