science

How This Harvester Literally Makes Water Out of Thin Air – Popular Mechanics


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Mathieu Prévot, UC Berkeley

  • Researchers at UC Berkeley created a water harvester that can pull more than five cups of water from low humidity air per day per 2.2 pounds of water-absorbing materials.
  • The goal is to create massive systems to harvest water for entire villages.
  • This method actually produces enough water for you to survive in extreme circumstances, with some left to spare.

    It sounds like a magic trick, but in a new paper for the Journal of the American Chemical Society, researchers from the University of California, Berkeley have unveiled a device that can literally turn thin air into water. The scientists’ water harvester can pull more than five cups of water from low humidity air per day per 2.2 pounds of water-absorbing materials. These, called metal-organic frameworks, are rather porous.

    That means you could produce enough water to live for a day. In fact, you’d actually have a surplus, according to the World Health Organization.

    “What it does is collect water from the atmosphere to very dry conditions and then releases it so we can harvest it as liquid water,” says Eugene Kapustin, a Ph.D. student at UC Berkeley, in a YouTube video released by the university.

    The star of the process is the metal organic framework, which is essentially a pile of powder full of organic molecules and metals. Scientists leave the mixture out overnight so that the wealth of water molecules floating around in the atmosphere can attach itself to the metal organic framework.

    “You can imagine it’s like a sponge,” Kapustin said.

    To extract the water, the mixture is placed in a water-tight tank and warmed with heat lamps. Droplets of water cling to the sides and then subsequently collected as pure H2O.

    The scientists wanted to study the topic given the scarcity of water around the world, but especially in California. They’re close to producing a microwave-sized water harvester that you could pull all of your water from—directly from the air. Even in the desert. Even in Phoenix.

    The harvester cycled 24/7 during a three-day field test in California’s Mojave Desert and was powered by solar panels and a battery. The device produced nearly three cups of pure H2O.

    “It is well known that in order to condense water from air at a low humidity—less than 40 percent relative humidity—you need to cool down the air to below freezing, to zero degrees Celsius, which is impractical,” Omar Yaghi, principal researcher, says in a prepared statement.

    “With our harvester, we are doing this at very low humidity without such cooling; there is no other material that can do that,” says Yaghi, who is also a UC Berkeley professor of chemistry. “This is not like a dehumidifier, which operates at high relative humidity. Some people say that 0.7 liters is not a lot of water. But it is a lot of water, if you don’t have water.”

    The startup for this project, Water Harvester Inc., will soon begin marketing a device about the size of an oven that can churn out 7 to 10 liters of water per day, enough cooking water for two or three adults per day.

    Plus, there’s a second version that’s more the size of a small refrigerator, which will produce 200 to 250 liters of water per day. That’s enough for an entire household to fill up glasses with drinking water, cook dinner, and take a shower each day.

    The company’s goal is to one day produce a village-scale harvester that can produce 20,000 liters of pure water per day. The entire process will be green, running on solar panels and batteries powered from the electrical grid.

    “This water mobility is not only critical to those suffering from water stress, but also makes possible the larger objective—that water should be a human right,” Yaghi says.

    Source: American Chemical Society



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