New solar-powered device creates water from thin air

In a "breakthrough", scientists have developed a novel solar-powered harvesting system that absorbs moisture from the air and converts it into clean, usable water.

The technology, described in the journal Advanced Materials, could be used in disaster situations, water crises or poverty-stricken areas and developing countries.

It relies on hydrogels, gel-polymer hybrid materials designed to be "super sponges" that can retain large amounts of water.

Researchers led by Guihua Yu from The University of Texas at Austin in the US used hydrogels that are both highly water absorbent and can release water upon heating.

This unique combination successfully worked in humid and dry weather conditions and is crucial to enabling the production of clean, safe drinking water from the air, the researchers said.

With an estimated 50,000 cubic kilometers of water contained in the atmosphere, this new system could tap into those reserves and potentially lead to small, inexpensive and portable filtration systems.

"We have developed a completely passive system where all you need to do is leave the hydrogel outside and it will collect water," said Fei Zhao, a postdoctoral researcher on Yu's team.

"The collected water will remain stored in the hydrogel until you expose it to sunlight. After about five minutes under natural sunlight, the water releases," Zhao said in a statement.

This technology builds upon a 2018 breakthrough made by the researchers in which they developed a solar-powered water purification innovation using hydrogels that cleans water from any source using only solar energy.

The team's new innovation takes that work a step further by using the water that already exists in the atmosphere.

For both hydrogel-based technologies, Yu and his research team developed a way to combine materials that possess both hygroscopic (water-absorbing) qualities and thermal-responsive hydrophilicity.

"The new material is designed to both harvest moisture from the air and produce clean water under sunlight, avoiding intensive energy consumption," said Yu, an associate professor of materials science and mechanical engineering.

The technology requires only solar power, is compact and can still produce enough water to meet the daily needs of an average household, researchers said.

Prototype tests showed daily water production of up to 50 litres per kilogramme of hydrogel, they said.