This Device Could Pull Liters of Water Out of Air Using Ambient Sunlight

Researchers from the University of California-Berkeley, in collaboration with mechanical engineers at Massachusetts Institute of Technology, have developed a new water harvester device capable of pulling liters of water out of the air using solar energy.

The new device, described in a paper published in the journal Science, was constructed by MIT using the so-called metal-organic framework or MOF produced at UC Berkeley. In conditions as low as 20 percent humidity, the solar-powered water harvester was able to produce more than two liters of water from the air over a 12-hour period.

"This is a major breakthrough in the long-standing challenge of harvesting water from the air at low humidity," said Omar Yaghi, who holds the James and Neeltje Tretter chair in chemistry at UC Berkeley and a senior author of the study, in a press release. "There is no other way to do that right now, except by using extra energy. Your electric dehumidifier at home 'produces' very expensive water."

For the study, the researchers created a water harvester consisting of more than two pounds of dust-sized MOF crystals made from the combination of zirconium metal and adipic acid. The MOF crystals were compressed between a solar absorber and a condenser plate, placed inside a chamber open to the air. The combination of zirconium metal and adipic acid is known to bind water vapor. When sunlight heats up the MOF, the bound water will be driven toward the condenser. The condenser plate has the same temperature as the outside air. The water vapor condenses as liquid water, dripping into a collector.

The prototype of the water harvester with 2.2 pounds of MOF, under conditions of 20 to 30 percent humidity, was able to pull three quarts of water from the air in a 12-hour period.

The researchers noted that the current MOF used in their prototype can only absorb 20 percent of its weight in water. However, other MOF materials could be altered, making it capable of absorbing 40 percent of its weight in water. Additionally, the materials can also be tweaked to be more effective at higher of lower humidity.