BRIEF: A Real-life Moisture Vaporator

(Inside Science) -- On the fictional Star Wars planet Tatooine, moisture farmers erect tall white structures called vaporators to pull valuable water from the desert air. Now researchers on planet Earth have built a device to perform the same basic task. They estimate a suitcase-sized version could harvest enough drinking water per day for a family of four. The device is described in a paper published in the journal Science.

The team, made up of scientists from the University of California, Berkeley and the Massachusetts Institute of Technology in Cambridge, expects the device to be most useful in arid regions and in areas where the traditional water supply is polluted. The system relies on the unique properties of a relatively new type of material called a metal organic framework, or MOF.

MOFs were originally created in the mid-1990s by stitching together metal clusters and organic, or carbon-containing, molecules to form a fine porous structure. The tiny pores help the materials absorb large amounts of liquids or gases.

The new water harvester relies on an MOF made from relatively cheap organic molecules and the metal zirconium to pull water out of the air. It releases the water later when it is heated.

The full device also includes an acrylic enclosure and a condenser. When the enclosure is open, most likely during the night, the MOF absorbs water from the air. During the day, the enclosure can be sealed and heat from the sun will release the water for collection by the condenser.

While other devices exist to harvest water from the air, they often require electricity to run, or only work in high humidity environments. In contrast, the new device works at the low humidity levels common in dry climates. The team tested the device in a natural outdoor setting, on an MIT rooftop, and successfully captured water with a prototype about the size of a coffee mug -- much smaller than the Star Wars vaporator, but still an important step toward a possible moisture-farming future.