TECH COULD PULL WATER FROM AIR
Not so long ago, in a neighborhood not that far away, researchers landed in suburban Phoenix to test a new technology with the goal of helping arid communities that need water.
The researchers weren’t wearing Jedi robes and the skies didn’t burn with Tatooine’s twin suns, but the technology and the experiment were reminiscent of “Star Wars,” specifically the moisture farms where young Luke Skywalker worked.
University of California, Berkeley researchers spent five October days in Scottsdale testing a next-generation harvester that produces water using nothing more than thin air and the energy of the sun.
“Imagine that you no longer need to buy bottles of water, and all you need to do is to push a button of a small machine,” said Omar Yaghi, who invented the technology.
And as Phoenicians know, there’s plenty of the sun to go around.
“The beautiful part of this device is that it’s all free,” said Eugene Kapustin, a graduate student who worked on the project. “That makes our
Researchers hope this technology can help communities starved for clean water.
technology a game-changer.”
How it works
First, it doesn’t use The Force. The harvester, which was built at the Massachusetts Institute of Technology, collects moisture during the night, when humidity levels are typically higher, and uses the sun’s energy during the day to turn that moisture into water.
It looks like a simple plastic box — because it mostly is, Kapustin said. The box, made of transparent plastic, holds 2 square feet of a fine powder they call Metal Organic Framework (or MOF, for short).
Researchers coat the top with the powder and leave the box’s lid open overnight.
As humidity rises at night, the powder collects moisture from the air and traps it. Come daytime, when, say, the blistering Arizona heat rears its head, the sun heats the box up like a greenhouse and the water molecules condense as liquid water.
“You really need to apply energy because there’s not much water in Arizona during the day,” Kapustin said. “It can capture water during the nighttime” — when humidity levels might reach about 40 percent.
For every 2.2 pounds of the metallic powder, the researchers were able to collect more than 3 ounces of water, he said.
What’s more: The water is clean and drinkable, he said.
The researchers originally used a zirconium-based powder, but have switched to one based on aluminum, which is cheaper and could produce up to four times as much water, Kapustin said.
“None of the existing technology can deliver a drop of water without using additional energy,” he said.
From the lab to the desert
It’s been a long journey. Yaghi’s team started developing the metallic powder more than 20 years ago, he said in an email conversation. To the naked eye, the powder looks like grains of sand, but it’s much more porous. One gram the size of a sugar cube has an internal surface area equivalent to a football field, he said.
The powder interacted with water molecules in the air in low humidity, they found. It seemed like a potential fix for desert climates, where — as the saying goes — it’s a dry heat. But they had to test it in the desert. So, they went to Scottsdale.
Why Scottsdale?
The “West’s most western town” may not be as desolate as Tatooine or the onehorse town that the city’s motto brings to mind, but it is the desert and it is hot. Really hot.
“We were trying to find the best conditions because we really needed to adjust our device to expose our powder as much as possible to sunlight,” Kapustin said.
The tech isn’t feasible for Arizona alone. It could come in handy for other arid areas that need water and don’t have a reliable source of energy other than the sun.
Its success rests partly on the area’s humidity.
“During the night, the temperature can be decreased substantially, and the humidity increases then. Obviously then our material can work,” he said. “The Middle East, Africa, southeast of the U.S. and Mexico — those are the perfect regions.”
Researchers are testing the harvesterlater this summerin Death Valley, where humidity can hover as low as 25 percent at night, to see how it works in extremely low humidity.
What’s next?
Researchers hope this technology can help communities starved for clean water. But getting the equipment there is another matter. Kapustin said some startups have approached them.
Yaghi, who is a faculty scientist at Lawrence Berkeley National Laboratory, is also working with King Abdulaziz City for Science and Technology in Saudi Arabia on the technology itself for their joint Center of Excellence for Nanomaterials and Clean Energy Applications.
They’re working on improving the system that would allow users to plug in the harvester at home and harvest water continuously, Yaghi said.
Ultimately, the system’s simple makeup could allow families to purchase their own down the line, he said. It could also help neighborhoods struggling to provide water, or cities like Flint, Michigan that struggle with water quality, he said.
“We found that it was pure, distilled water,” he said. “You can drink it right away.”