Water from Air, No Electricity Required

Yep, that’s what this story from News Deeply says. Wow!

An excerpt.

Water is all around us. The only problem is that it remains trapped in the atmosphere until the right conditions release it as rain or snow. Now Omar Yaghi, a chemistry professor at the University of California, Berkeley, has helped find a way to grab that water anytime we need it.

Yaghi says it is possible using something called a metal-organic framework (MOF). This is basically a sponge-like compound that looks like sand to the naked eye, and which is extremely dense. Depending on the materials involved, the MOF can be constructed to harvest different chemicals, from industrial emissions to natural gas.

Yaghi and his team at U.C. Berkeley found that a metal-organic framework that includes the element zirconium will capture water out of the air at night, store it, then release it during the daytime upon exposure to the heat of sunlight – no electricity needed. They collaborated with researchers from the Massachusetts Institute of Technology to build the water-collecting device and are working to develop a version with the capacity to serve a single-family home at a competitive price.

Other devices are capable of capturing water from the air in humid environments, like so-called “fog catchers” tested successfully around the world. What makes their invention so remarkable is that it works especially well in arid environments, like those that exist throughout the West. Water Deeply recently interviewed Yaghi to learn more.

Water Deeply: What was your inspiration for this water-harvesting device?

Omar Yaghi: We were actually studying the trapping of carbon dioxide using metal-organic frameworks from post-combustion gases, which include water. Water presents a challenge since it competes with carbon dioxide for the adsorptive sites in the pores of MOFs.

We noticed that some MOFs exhibit a unique uptake of water. A highly cooperative phenomenon seems to dominate the uptake and result in a sharp water permeation of the MOF at very low relative humidity. In essence, inside these MOFs, one has solid water in hot weather.

Water Deeply: And once inside the MOF, how do you get the water out?

Yaghi: To get the water out, as the goal is liquid water, one simply needs to heat the materials to a mere 45C (113F). This is the temperature [needed] inside the enclosed device, which can be a lot higher than the ambient outdoor temperature – similar to the greenhouse effect. This provides enough energy to break those weak bonds and release the water from the pores. This was very surprising, but also exciting. It meant that certain MOFs can be used to trap water from the atmosphere especially in arid climates, and then be released easily for collection.

However, we quickly realized that the only way to accelerate the development of this water-harvesting technology is through worldwide collaborations and competitions. Before that can happen, the world needs to visualize this chemistry in action first.

Water Deeply: And how did you make that happen?

Yaghi: We teamed up with mechanical engineers to design and build a simple harvester around the MOFs. Together with our collaborators, we demonstrated that a MOF-based device is capable of delivering clean water even in typical desert climates. Remarkably, the device operates without any power input, aside from ambient sunlight.

The MOF is exposed to the atmosphere, bringing water from dry air into its pores and concentrating it. Then, upon enclosing the MOF into a container, which is exposed to sunlight, the container heats up and water is released from the MOF into the container as high humidity. This, in turn, is condensed by virtue of the temperature difference between the warm interior of the container and room temperature.

The water harvester works passively and can be placed in the desert to trap water at night and release it during the day when the temperature rises. This technology has just been showcased at the 2017 World Economic Forum as one of the top 10 emerging technologies to change the world.

Retrieved May 31, 2018 from https://www.newsdeeply.com/water/community/2018/05/31/new-device-produces-water-from-thin-air-no-electricity-required

About David H Lukenbill

I am a native of Sacramento, as are my wife and daughter. I am a consultant to nonprofit organizations, and have a Bachelor of Science degree in Organizational Behavior and a Master of Public Administration degree, both from the University of San Francisco. We live along the American River with two cats and all the wild critters we can feed. I am the founding president of the American River Parkway Preservation Society and currently serve as the CFO and Senior Policy Director. I also volunteer as the President of The Lampstand Foundation, a nonprofit organization I founded in 2003.
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