Researchers at the Massachusetts Institute of Technology created a groundbreaking device that uses solar energy to harvest water out of thin air, even in dry or desert climates.
For the construction of their solar-powered water harvester, MIT scientists employed a special material, called metal-organic framework or MOF, which was developed by the University of California, in Berkeley.
The framework combines metals like magnesium or aluminum with organic molecules to create a rigid, porous structure ideal for storing gases and liquids.
The invention, with details published April 13 in the journal Science, relies on ambient sunlight to pull water out of the air on a daily basis in low humidity conditions.
How The Water Harvesting Device Works
In collaboration with MIT's Device Research Laboratory — run by Dr. Evelyn Wang, the inventor of MOF — Omar Yaghi, a scientist at the Lawrence Berkeley National Laboratory, synthesized a zirconium-based material that binds water vapor and transforms it into a water-collecting system.
The system absorbs condensed water at night-time and evaporates it again during the day, through a series of porous crystals that form continuous 3D networks. Under the heat of the sun, water molecules begin to vaporize again, eventually condensing into reservoirs designed to collect the water.
"This device is capable of harvesting 2.8 liters of water per kilogram of MOF daily at relative humidity levels as low as 20%, and requires no additional input of energy," states a DRL news release.
This was achieved in a span of 12 hours and by using 2.2 pounds of MOF, with the machine running continuously.
"There is no other way to do that right now, except by using extra energy," says Yaghi.
'Personalized Water'
According to Yaghi, the newly developed invention could pave the way for off-grid water supplies. In the future, the solar-powered harvester could provide water for entire households via ambient solar energy.
"To me, that will be made possible because of this experiment. I call it personalized water," notes the MOF creator.
Since the material's invention more than 20 years ago, the technology has seen over 20,000 different adaptations. Scientists all over the world have appropriated the MOF design to develop durable high-volume containers for storing chemicals, such as hydrogen or methane.
As Wang explains, the solar-powered device presents a reliable alternative to currently used water-harvesting technology, which it surpasses from an energy efficiency stand-point.
"If you want to get to a 30-liter quantity, to demonstrate the real viability of this, you would need to incorporate multiple stacks of this MOF layer into a device," Wang said.
One of the things the researchers were aiming to prove is their device could guarantee survival in arid regions. The basic water requirement for survival in the desert is around 12 ounces, or about the content that fits in a soda can.
"That is something one could collect in less than an hour with this system," Yaghi points out.
