New device can harvest water from arid desert air

March 22 (UPI) -- In field tests, a new water-harvesting device successfully pulled water from the desert air in Tempe, Arizona. The new technology could allow humans to survive in some of the most inhospitable regions on Earth.

The new device -- described this week in the journal Nature -- is an improved version of the initial iteration, first described last year. When researchers at MIT first unveiled the device in 2017, skeptics voice a number of criticisms.

"All of the questions that were raised from last time were explicitly demonstrated in this paper," Evelyn Wang, a professor of mechanical engineering at MIT, said in a news release. "We've validated those points."

The device uses metal-organic frameworks, a unique material with an expansive internal surface area and molecule-trapping structures. Current water-harvesting devices require high humidity levels and are energy intensive.

The MOFs used in the device are made from water-attracting materials and painted black on top to encourage the absorption of sunlight. The water vapor is pulled into the material's tiny inner pores where the difference in temperature and concentration causes the vapor to condense and drip to the bottom.

Scientists field-tested their new device on the roof of an Arizona State University building -- "in a place that's representative of these arid areas, and showed that we can actually harvest the water, even in subzero dew points," Wang said.

The new device was powered only by sunlight. At present, the prototype is small, but researchers say it can easily be scaled up. Tests showed the device harvests a quarter-liter of water per day per kilogram of MOF material. Tests also showed the water is potable and free of impurities.

Because the device has no moving parts, scientists are confident that the technology is practical and can be deployed in the field.

By scaling up the technology and perfecting the metal-organic framework, scientists hope to triple the water output of their technology.

"We hope to have a system that's able to produce liters of water," Wang said. "We want to see water pouring out!"