US researchers have created a device that can extract water from dry desert air, without using an external fuel source.

The same team had earlier unveiled a zirconium-based powder called meta-organic framework 801 (MOF-801), which is extremely expensive to produce.

Now, a new version of the device has an aluminium-based framework with more than double the water-capturing capacity, which can be made at around one-hundredth the cost of the previous design.

The key is the massive surface-area-to-mass ratio of the MOF powder, according to researcher Eugene Kapustin.

“It's very porous. It has an enormous amount of space inside. The surface area of one gram of this MOF can cover several soccer fields,” Mr Kapustin said.

“So you can imagine that you can store substantial amounts of gas within the pores of this material.”

At night, the device opens up to take advantage of saturated desert air, allowing water to be absorbed by the MOF powder.

During the day, the insulated case is closed and an aerogel on top of the MOF powder absorbs heat from the sun.

Water vapour is released from the heated powder and comes in contact with a condenser which has cooled overnight - this cools and condenses the vapour, allowing the liquid to be collected.

More details are available here.