We know the next big series of wars is going to be over water. And, no, I’m not talking about how neighbors in California will be fighting over their water allocations (or even California fighting with Colorado). I’m talking about the vast portions of this Earth that are basically out of water.

Right now, many locations are using reverse osmosis (RO) to desalinate sea water or waste water. As an example, Israel is currently supplying itself, Jordan, and the West Bank with desalinated water from the Mediterranean.

But, RO needs lots of energy to produce pure water. And, while some folks have managed to deliver the power via solar energy (which means it’s renewable- but not cheaper), we still are seeking new methodology to solve this world-wide water crisis.

One such idea is not for large scale production- but could produce water for individuals and small families. Especially since this device is just a little bigger than the toaster oven in your kitchen. And, it obtains get all the power it needs via solar energy (with a twist).

Oh – the kicker? It obtains this water from the atmosphere- as long as the humidity is 20% or higher. (That means the device has utility even in the Sahara Desert .)

This has been a joint project between professors at MIT and UC Berkeley. Dr. Omar Yaghi of Berkeley and Evelyn Wang of MIT headed up the project, with Drs. H. Kim, S. Yang, S.R. Rao, S. Narayanan, and U. Umans (all of MIT) and Drs. E.A. Kapustin and H. Furukawa of Berkeley completing the team. These techies explained  the current phase of their research in Science .

Back 20 years ago, it was Yaghi who started working with MOF’s (metal organic frameworks). These crystals develop intricate 3D networks, and by choosing the right mix of metal atoms, one can choose which gas will adhere to the framework. By 2014, he developed an MOF that was fantastic at sucking water vapor from the air. (The MOF is basically akin to a metallic sponge.) That’s when the liaison with Dr. Wang of MIT began; focusing on a zirconium based MOF (MOF-801, [Zr₆O₄(OH)₄(fumarate)₆]).

Basically, the new device operates in two phases. At night, the “box” is opened to the atmosphere, allowing air to flow into the device; this affords water vapor to become entrenched within the MOF structure. Then, during the day, the chamber is closed, and the sun’s heat ( 1 kW per square meter) causes the framework to release and condense the water vapor, when it is collected. About 2.8 Liters per day are produced with no outside energy source. (The MOF itself is about 1 kg pressed into a thin sheet of copper.)

(There have been two ways to harvest water from air. One is fog harvesting- water is cooled and condensed from clouds or fog. The fog approach affords a relative humidity of 100%. The other way, of which this device is a variant, is called dewing. In such cases, water condensers pull the vapor out of the air and condense it to liquid- but, except for this case, the process needs copious energy (to maintain the condenser at the optimum temperature- and the device still needs a high humidity level in the air.)

The team has hopes to make a device that can produce 30 L of water a day- but it will cause the size to become that of a small valise. But right now, 2.8 liters is more than one human needs per day, so the other trick is to lower the price of the MOF device to make it affordable.

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