Solar-powered device harvests litres of drinking water from thin air

Breakthrough technology offers solution for arid regions and areas hit by water scarcity

A solar-powered water harvester than can generate up to three litres of water each day (KAUST)

Researchers have invented a solar-powered device capable of extracting several litres of water from thin air in a single day.

The new self-sustaining technology could provide a lifeline for people living in arid regions, according to the team that developed it from King Abdullah University of Science and Technology (KAUST) in Saudi Arabia.

The system works in a two-stage cycle that first captures water from the air with an absorbent material and then extracts it within a sealed chamber using heat from the sunlight.

Two-stage systems typically require manual labour to switch from one cycle to another, however the new technology automatically alternates between the two without need for intervention.

“Our initial inspiration came from observing natural processes: specifically how plants efficiently transport water from their roots to their leaves through specialised structures,” said Kaijie Yang, who led the study.

“In our system, mass transport bridges play a crucial role as a connection between the ‘open part’ for atmospheric water capture and the ‘closed part’ for freshwater generation.”

The system can generate two to three litres of water per square metre each day, which can be used to drink or for farming. The researchers demonstrated that it could be used to irrigate Chinese cabbage and desert trees.

The passive technique allows for continuous operation without intervention, while running the system for several weeks during tests required no maintenance.

Operational costs are also reduced by the materials used, which include a water-wicking fabric, a low-cost hygroscopic salt and a plastic-based frame

“We chose the materials for their affordability and availability, so we anticipate the cost is affordable for large-scale application in low-income areas,” said KAUST researcher Qiaoqiang Gan.

The device was detailed in a study, titled ‘A solar-driven atmospheric water extractor for off-grid freshwater generation and irrigation’, which was published in the journal Nature Communications.

The breakthrough comes amid a flood of emerging water harvesting technologies, which have been driven by water scarcity issues induced by climate change.

An MIT-designed system collects moisture from the air and releases the trapped liquid as potable water when heated (Xiangyu Li)

In June, scientists from Massachusetts Institute of Technology (MIT) unveiled a new device that can extract potable water from the air using water-absorbent ‘fins’.

Last month, Nasa unveiled a new spacesuit design that can recycle urine into drinking water in less than five minutes.