Rooftop oasis extracts water from dry desert air

Stranded in the desert, the idea of extracting water from nothing but the dry air might seem like another dehydrated hallucination – but researchers claim they have made it possible.

Led by mechanical engineers from the Massachusetts Institute of Technology and the University of California in the US and with colleagues from Saudi Arabia, the team created a device which they claimed could be upgraded to “fill an unmet need for water, even in the world's driest regions.”

The solar-powered creation uses high surface area materials called metal organic frameworks (MOFs) to extract water from even the driest of desert air, with relative humidity as low as 10%. Water from the air binds to pores in the sponge-like MOFs after being heated by the solar energy.

“This has no moving parts,” said lead author Sameer Rao. “It can be operated in a completely passive manner, in places with low humidity but large amounts of sunlight.”

The team tested the device on a rooftop in the bone-dry air of Tempe, Arizona. The prototype was designed to only produce a few millimetres, but the researchers claimed it could extract 0.25l of water every day per kilogram of MOF if scaled up. Optimising material choice could triple the device’s output, which could also be powered by burning fuel or using waste heat.

“We hope to have a system that's able to produce litres of water,” said senior author Evelyn Wang. “We want to see water pouring out.”

With climate change bringing longer and more severe droughts worldwide, the team hopes similar systems could provide enough water for individual households in dry countries.

The research was published in Nature Communications.

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