Berkeley Scientists Develop Genius Device to Harvest Water From Desert Air

Advance will make arid future dystopias much more bearable

UC Berkeley

People worried about the inevitable Water Wars of our Mad Max-esque future can rest a little easier this week, thanks to new research suggesting that desert air may soon be converted into potable drinking water in a cost-effective manner.

This new generation of harvester will be able to produce about a soda can’s worth of water each day for every kilogram of “metal-organic framework,” in the device. Metal-organic frameworks — MOFs for short — refer to the highly porous, usually costly materials that suck water molecules out of the air like a sponge. Researchers say they hope that by swapping out the expensive metal zirconium with aluminum, the devices will soon be about 150 times cheaper to make.

“This laboratory-to-desert journey allowed us to really turn water harvesting from an interesting phenomenon into a science,” said Omar Yaghi, who invented the device’s underlying technology, in a press release. “The key development here is that it operates at low humidity, because that is what it is in arid regions of the world.”

The device is sort of a box within a box, and allowed researchers to harvest water out of even dry, desert air. 

Roxanne Makasdjian and Stephen McNally

Water Harvesting Techniques Are Getting Better

Approximately 2.1 billion people lack access to safely managed clean water, and roughly four out of every 10 people suffer from some form of water scarcity, according to estimates by the World Health Organization. The researchers, a team from Berkeley’s Global Science Institute, are now working on adapting their new proof-of-concept material with more cost-effective metallic compounds.

At the core of the new device is a unique MOF of zirconium metal, hydrogen and oxygen bonded together in a complex, porous structure. Despite being volume of just a sugar cube, the MOF holds a total internal and external surface area of six football fields. You can think of it like a nano-scale sponge that’s specifically tuned for absorbing water and really good at conducting heat.

Heating the material, in fact, is the method by which all that absorbed water drains out into pure drinkable water. As published late last week in Science Advances, the Berkeley team lead by Yaghi constructed their moisture collector so that it could operate solely on energy input from the sun.

Slate-grey and sandy, the zirconium metal-organic framework material, MOF-801, is the stuff that looks like moon dust spread thinly onto the pan on the device’s surface.

Each day, the new devices extract about as much water from the air as you'd fine in a 12 ounce can of soda. 

Currently, the Berkeley team is working on a cheaper MOF that substitutes aluminum for zirconium. They have also doped both of these MOFs with nonporous graphite that, according to their paper in Science Advances, more than doubled the water intake of their device (a “114-percent increase in water production”).

As mentioned in the MIT Technology Review, Yaghi also anticipates that this technology could be paired with solar panels to harvest water for industrial or agricultural use.

But it’s Yaghi’s main hope that the purely passive energy requirements for the device can be paired with low-cost materials so that these moisture collectors could become household appliances in developing nations where clean water (or any water) has been scarce.

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