Breakthrough air-to-water converter works even at night, generates 20L daily

Researchers at the Mechanical Engineering Department at the University of Utah have designed a compact device that harvests water directly from the air. The device could help soldiers serving in arid regions. It works with regular fuel and can, therefore, work around the clock.

Atmospheric water harvesting (AWH) is touted as the solution to the challenge of providing clean drinking water to billions worldwide. Estimates suggest that water content in the Earth’s atmosphere can fill an entire ocean.

The Department of Defense runs a technology transfer program focusing on using science and technology to improve soldiers’ performances. The team recognized the need for hydration for soldiers operating in areas with scarce water resources and approached the University of Utah for possible solutions.

Lego-like blocks adsorb water

The device relies on a hygroscopic material, similar to the stuff inside diapers, which has a high absorption capacity and does not let out liquid easily. The difference is that the material absorbs water vapor from the air instead of liquid water.

“We work with a specific type of hygroscopic material called a metal organic framework (MOF),” explained Sameer Rao, assistant professor at the John and Marcia Price College of Engineering, University of Utah.

MOFs can also be considered similar to Lego blocks, where rearrangements can build new structures. Using an MOF called aluminum fumarate, Rao’s team made a structure that could selectively adsorb water vapor from the air.

The water molecules do not react with the material instead are trapped on the surface, which also makes it easier to remove them. Just one gram of the material can adsorb water spread over the surface area of two football fields, a press release said.

“All of this surface area is at the molecular scale,” added Rao. “And that’s awesome for us because we want to trap water vapor onto that surface area within the pores of this material.”

Harvesting water with a gas stove

In a prototype developed by the team, the compact device adsorbed 1.3 gallons of pure water (five liters) using one kilogram of hygroscopic material daily. Retrieving the adsorbed water was also easy; only heat was needed to be applied to the material.

This could be achieved for the Army using an easily available camping stove. According to the researchers, multiple atmospheric water harvesting (AWH) technologies are being developed today. However, they are not practical due to their size, cost, or efficiency.

The team purposely avoided using solar panels in their setup since it could limit the operation of the device in the daytime or increase the weight to be carried by the personnel in the form of operating batteries.

Beyond its utility for the Army, the technology is also useful for civilians. It can be easily deployed in remote locations where piped water infrastructure does not exist and inhabitants are facing severe water shortages.

A small-sized device could easily meet household needs of 4-5 gallons (15-20 liters) daily.

The research findings were published in the journal Cell Reports .