New machine harvests water from thin air in dry environments

Earth’s atmosphere contains an immense amount of water, enough to fill Utah’s Great Salt Lake 800 times. This vast resource has the potential to pull clean drinking water out of thin air for billions of people facing global shortages.

Existing atmospheric water harvesting (AWH) technologies are hindered by size, cost, and efficiency issues.

However, research led by a team of scientists at the University of Utah has offered promising advancements that could revolutionize this field.

Transforming dry air into water

The study introduces a compact, fuel-fired AWH device that relies on adsorbent materials to draw water molecules from the air and release them as liquid through heat application.

This amazing prototype, developed by senior author Sameer Rao and graduate student Nathan Ortiz, uses a specific type of hygroscopic material called a metal-organic framework.

“Hygroscopic materials intrinsically have affinity to water. They soak up water wherever you go,” Rao explained. This material, similar to the absorbent found in diapers, is designed to selectively adsorb water vapor from the air.

Rearranging molecules

Rao compares the metal-organic frameworks to Lego blocks, which can be rearranged to create molecules ideal for gas separation.

“They can make it specific to adsorb water vapor from the air and nothing else. They’re really selective,” he said. The prototype employs aluminum fumarate, fashioned into panels that collect water as air is drawn through.

“The water molecules themselves get trapped on the surfaces of our material, and that’s a reversible process. There are so many sites for water molecules to get stuck,” Ortiz added.

Just a gram of this material holds as much surface area as two football fields, enabling it to capture a significant amount of water. “All of this surface area is at the molecular scale,” Rao said.

“And that’s awesome for us because we want to trap water vapor onto that surface area within the pores of this material.”

Water from air for soldiers and civilians

The research received funding from the DEVCOM Soldier Center, a Department of Defense program aimed at technology transfer to support Army modernization.

The Army’s interest lies in providing soldiers with a compact water generation unit, reducing the need to carry large water canteens.

“We specifically looked at this for defense applications so that soldiers have a small compact water generation unit and don’t need to lug around a large canteen filled with water,” Rao explained. “This would literally produce water on demand.”

Rao and Ortiz have filed for a preliminary patent on the technology, which also addresses civilian needs.

“As we were designing the system, I think we also had perspective of the broader water problem. It’s not just a defense issue, it’s very much a civilian issue,” Rao said.

Addressing global water shortages

The goal is to provide households with enough drinking water, approximately 15 to 20 liters per day.

The proof-of-concept prototype successfully produced five liters of water per day per kilogram of adsorbent material.

In field conditions, this device would outperform the practicality of packing water within three days, according to Ortiz.

The device’s second step involves precipitating water into liquid by applying heat, using a standard Army camping stove.

“As it collects water, it’s releasing little bits of heat. And then to reverse that, we add heat. We just put a flame right under here, anything to get this temperature up. And then as we increase the temperature, we rapidly release the water molecules,” Ortiz explained.

Sustainable solution turns air into water

While there are many emerging technologies for atmospheric water harvesting, they are typically effective in humid environments but not practical in arid regions.

Ortiz believes their device can be the first to succeed in arid conditions, primarily because it uses energy-dense fuel like white gasoline.

The team decided against using solar panels due to limitations related to daytime operation and battery storage.

“If you’re reliant on solar panels, you’re limited to daytime operation or you need batteries, which is just more weight. This technology is superior in arid conditions, while refrigeration is best in high humidity,” Ortiz said.

The study, published in the journal Cell Reports Physical Science,  marks a significant step toward practical atmospheric water harvesting, offering a potential solution for areas facing chronic water shortages.

With continued development, this technology could play a crucial role in providing sustainable water sources in both military and civilian contexts.

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