Scientists have created a device that can pull drinking water from the air using only the power of sunlight. The water harvester is so effective that it even works well when humidity is as low as 20 percent—typical of many of the driest regions on Earth.

Chemist Omar Yaghi of UC Berkeley said, “We wanted to demonstrate that if you are cut off somewhere in the desert, you could survive because of this device.”

Yaghi invented compounds known as metal-organic frameworks (MOFs) 20 years ago, and now is using MOF crystals to harvest water even in dry places. In the water harvesting device, around two pounds of tiny MOF crystals are compressed between a solar absorber and condenser plate to collect around 0.7 gallons of water in 12 hours.

That may not sound like all that much, but it’s plenty for a human trapped in the desert to survive. Yaghi said, “A person needs about a [330ml] can of water per day. That is something one could collect in less than an hour with this system.”

Right now there’s no other way to harvest water in low humidity except to draw on extra energy, according to Yaghi. “Your electric dehumidifier at home ‘produces’ very expensive water,” he says. In contrast sunlight enables the new device to work. Rooftop tests at MIT have already demonstrated the device works in the real world.

Even if you never find yourself stranded in the desert, you could benefit from such a water harvester. “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,” said Yaghi. “To me, that will be made possible because of this experiment. I call it personalized water.”

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