Getting water from air may sound magic to many but scientists from MIT, including an Indian-origin postdoc fellow, have succeeded to get drinkable water right out of the driest of desert air.
Since some moisture is always present even in the most arid places on Earth, a practical way to extract that moisture remained the major challenge for many decades and now researchers at MIT have proved it feasible.
The new device, successfully field-tested in the dry air of Tempe, Arizona, was reported in the journal Nature Communications and includes some significant improvements over the initial concept that was revealed last year in a paper in Science, says Evelyn Wang, a Professor in the Department of Mechanical Engineering, MIT who was the senior author of both papers.
Indian-origin MIT postdoc Sameer Rao and former graduate student Hyunho Kim were the lead authors of the latest paper, along with four others at MIT and the University of California at Berkeley.
They were able to use new high-surface-area materials called metal-organic frameworks (MOFs) to extract potable water from very dry desert air with relative humidities as low as 10 percent.
In the past, similar methods developed for extracting water from air require 100 percent humidity for fog-harvesting methods, and above 50 percent for dew-harvesting refrigeration, which require large amounts of energy for cooling. But the new system could potentially get water even in the world’s driest deserts.
“We can actually harvest the water, even in subzero dewpoints,” said Wang. The test device was powered solely by sunlight, and is too small in size but needs to be scaled up by three times to get about a quarter-liter of water per day per kilogram of MOF, the researchers said.
Not only does this system work at lower humidities than dew harvesting does, said Sameer Rao, but those systems require pumps and compressors that can wear out, whereas “this has no moving parts. It can be operated in a completely passive manner, in places with low humidity but large amounts of sunlight.”
The current version can only operate over a single night-and-day cycle with sunlight, Kim added.