Solar-Powered Dehumidifier Pulls Fresh Water Out of Thin Air

Professor Omar Yaghi, who led the study, said: 'This is a major breakthrough in the long-standing challenge of harvesting water from the air at low humidity. MOFs are still in experimental stages, but chemical companies have started scaling them up for commercialization-and right now Wang said she could buy them for about 10 dollars per kilogram (though other MOFs are far more expensive).

Yaghi, a chemistry professor at University of California, Berkeley, envisions a future where the water is produced off-grid for individual homes and possibly farms using the device. A demonstration took place a few days ago regarding a water harvester that employs sunlight to pull many liters of water out of the air on a daily basis.

The new water harvester is made of metal organic framework crystals pressed into a thin sheet of copper metal and placed between a solar absorber (above) and a condenser plate (below). They have used Zirconium and adipic acid for designing this MOF. Then, if you put it in the sun, that heats it up and forces it through a condenser, offering more than two liters of water a day from places with humidity as low as twenty percent.

Device that turns air into drinking water. It is now a prototype, but has passed tests in real-world conditions.

Now the MOF can only absorb 20 percent of its weight in water but Yaghi and his team hope to double its efficiency in the future.

The current prototype can only absorb about 20 per cent of its weight in water, but it is thought using other MOF types could boost this to more than double that. Nearly half of the people getting water from unprotected sources live in sub-Saharan Africa, and eight in 10 live in rural areas.

To collect the water, scientists turned to metal organic frameworks, or MOFs. "To me‚ that will be made possible because of this experiment". Since Yaghi developed MOFs, over 20,000 different types of MOFs have been created around the world that can hold hydrogen and methane or that can contain petrochemicals in processing plants. Their device works at low power and in arid conditions, which means it could help remote desert communities without constant access to fresh water. The MOF has a porous structure that makes it ideal for holding water, similar to a sponge.

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. During daytime, the chamber is closed and sunlight enters through a small window on top of the device to heat up the MOF.

As an active ingredient, so to say, in the recipe of creating water from air, MOFs are what happens when one blends metals with organic molecules, creating highly absorbent compounds that could store liquids or gas.

The device is billed as a proof of concept by Yaghi, so it's just a starting point. "It is just a matter of further engineering now". The research team, hailing from the University of California, Berkeley, and the Massachusetts Institute of Technology (MIT), USA, sought to unlock that vapor.

"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.

The entire device operates off ambient sunlight, Yaghi noted - no solar cells or external power sources are needed to make it work.

  • Tracy Ferguson