New device can turn air into water using only the power of the sun

14 Apr 2017

Water harvester developed at MIT. Image: MIT/laboratory of Evelyn Wang

With the onset of climate change, a new device that can turn air into water using only the power of the sun could be a game-changer.

In the science-fiction classic Dune, people living on the desert planet Arrakis wore a full-body suit – referred to as a stillsuit – that recycled and used all of the body’s moisture to survive the brutal climate.

While such a suit remains in the sci-fi realm, researchers over at MIT may have found an ingenious and affordable solution to the world’s water crisis, which leaves 10pc of the planet’s population without access to safe water.

Passively harvests water

In a paper published to the journal Science, the MIT researchers revealed a solar-powered harvester that works on ambient sunlight.

Throughout the day, the device will then pull litres of water from the surrounding air in conditions as low as 20pc humidity.

To do this, the team used a special material called a metal-organic framework (MOF) that combines metals including magnesium or aluminium with organic molecules to create rigid, porous structures – ideal for storing gases and liquids.

The first signs that MOF could be used to harvest water were seen in 2014 when Omar Yaghi – one of the researchers involved in this project and the original inventor of MOF – had success with a combination of zirconium metal and adipic acid.

With help from fellow MIT engineer Evelyn Wang, the pair created almost 1kg of dust-sized MOF crystals compressed between a solar absorber and a condenser plate, placed inside a chamber open to the air. When the air diffuses through the MOF, the water molecules attach to the interior surface.

Using the MOF, the pair’s latest prototype was able to pull 2.8 litres from the air over a 12-hour period using 1kg of MOF.

Room for improvement

“One vision for the future is to have water off-grid, where you have a device at home running on ambient solar for delivering water that satisfies the needs of a household,” explained Yaghi.

“To me, that will be made possible because of this experiment. I call it personalised water.”

There is still much room for improvement however, with Yaghi admitting that the current iteration of MOF can only absorb 20pc of its weight in water, but other MOF materials could possibly absorb 40pc or more.

“There is a lot of potential for scaling up the amount of water that is being harvested. It is just a matter of further engineering now,” he said.

Similar efforts to harvest water in the face of climate change have seen the development of a graphene sieve that can quickly turn seawater into safe drinking water.

Colm Gorey was a senior journalist with Silicon Republic