A new prototype developed by researchers at the University of California, Berkeley, and the Massachusetts Institute of Technology (MIT) may provide the technology to harness the power of the sun to pull water out of the air – allowing households around the world to gain access to safe, clean water.
Worldwide, an estimated 4 billion people are currently facing serious water shortages, and as many as 1 in 10 people lack access to clean drinking water. With this prototype, people in even the driest regions of the world would be able to harvest their own water right from the atmosphere – the device is able to pull water from the air even in conditions where the relative humidity is as low as 20 percent.
“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 Berkeley chemistry professor Omar Yaghi, who co-authored the new research after inventing metal-organic frameworks (MOFs) twenty years ago.
“To me, that will be made possible because of this experiment. I call it personalised water.”
Yaghi and a team of researchers were able to convert the chemical compound of an MOF to be hydrophilic – and in powder form, this compound can absorb liquid water as well as suck water vapour right out of the air. To create the device, MOF powder is applied in a thin layer between two surfaces. The black top surface absorbs solar heat, and the bottom surface maintains the same temperature as the surrounding air.
Water vapour is then absorbed through the powder. The heat generated by the top layer releases the water to the cooler lower surface, where it is collected as liquid. Just one kilogram of MOF powder collected nearly three litres of water per day in trials.
“This is a major breakthrough in the long-standing challenge of harvesting water from the air at low humidity,” said Yaghi. “There is no other way to do that right now, except by using extra energy. Your electric dehumidifier at home ‘produces’ very expensive water. This works offers a new way to harvest water from air that does not require high relative humidity conditions and is much more energy efficient than other existing technologies.”
The research was funded in part by a United States government agency, ARPA-E, which aims to support the early development of energy technologies that have the potential to make a significant global impact. Further development of this prototype could provide technology to harvest water around the world at any level of humidity – by using the atmosphere as a water source, we could access more than enough water to provide for populations around the world, without having to disrupt our environment.
“There is a lot of potential for scaling up the amount of water that is being harvested, it’s just a matter of further engineering now,” Yaghi said. “We wanted to demonstrate that if you are cut off somewhere in the desert, you could survive because of this device.”