Water From Air—A Miracle Solution?

Fact—10% of the Earth’s fresh water, an estimated 13 trillion liters, is found in its atmosphere.

Fact—in humid climates up to 6% of the air contains fresh water. In arid climates the air still contains an average of 0.7% water.

Fact—over 700 million people in 43 countries are suffering from lack of fresh water. This number is estimated to more than double in the next 10 years. [1]

Atmospheric Water Generator (AWG)—An Old Idea, Modern Technology

I was speaking to an inventor friend and mentioned a start-up that’s working to develop “drinkable air” from the air that we breathe. He said that this is nothing new: when Carrier invented the air conditioner in 1902, a by-product was distilled water.

There have indeed been water generators for a long time, based on the dehumidifier. As air is passed through a cooled electric coil, water condenses. The problem with this method of generating water is that it has the hugest carbon footprint of any water source — over three times larger than a desalination plant. In fact the amount of water used in the classic AWG method of harvesting condensed water is four times greater than the quantity that is eventually delivered to the user. [2]

This large carbon footprint has been the Achilles heel of companies such as AquaMagic, which claims that its generators can produce 120 gallons of fresh water a day, with the only problem being in that it takes 12 gallons of diesel to produce those 120 gallons of water.

In 2007 inventor Max Whisson publicized his solution to the world’s water shortage: the Whisson Windmill. This $43,000 windmill passes air over cooled coils, with the generator powered by the windmill. Self-contained and completely green, Whisson claimed that his windmill could produce 2,600 gallons of water a day.

However Whisson couldn’t interest investors to help him get his ingenious idea from the workshop to the marketplace because there was virtually nothing that could be patented. As of late Whisson has made some design changes that he hopes will be patentable. [3]

Water From Air—What’s New?

Two new technologies are making their mark in the drinkable air race.

The first technology has been around for a couple of millennia — a fog collector. Used by the ancient Incas and still used in countries such as Chile for making beer, a fog collector is simply a mesh net designed to collect fog (a cloud composed of tiny droplets of water). This simple device, however, is very inefficient, transforming less than 2% of the available fog into water. There is no method for attracting the fog to the collector; in fact the wind usually blows the fog around the netting.

Earlier this year, however, there was a breakthrough in the realm of fog collection. An Associate Professor at MIT, Kripa Varanasi, discovered that when charging the droplets by passing them through an ion emitter, 99% of them are gathered by the collector.

The problem with this supercharged collector is that to make it worth the investment you need a large and constant amount of fog — which cannot be guaranteed in most locations and hardly ever in arid countries where it is needed the most. [4]

MOF—Metal Organic Frameworks

The hottest new idea for creating water out of thin air comes from the University of California. Led by Omar Yaghi, a team of engineers created a new type of Metal Organic Framework. MOFs, which have been around for 20 years, are compounds comprised of metal ions or clusters as well as organic ligands. Using different metals and organic ligands the MOFs trap different gases.

Using zirconium as the metal and carbon atoms as the organic ligand, they created a sponge-like material that captures the humidity in the air, no matter what the climate. The MOF sits in a box, which sits in yet another box that collects the water sponged out of the air by the MOF.

Initial models only produced about 1/8 of a liter of water for every pound of MOF. But using different metals, such as aluminum alloys, has tremendously lowered the costs while increasing the output of clean water. As of March 2017 they are able to squeeze out three liters of water for every one kilogram of MOF. [5]

The Final Note

There are already companies like Drinkable Air and Water Gen that use AWG technology and sell their products to both industry and the home. And while we wait for fog collection and MOFs to become viable air to water solutions, other new technologies are being worked on around the world.

Although there is reason to be optimistic about these technologies, we do have to be careful when playing with Mother Nature. Changing the humidity in the air will have repercussions. What these repercussions are, only time will tell.

One can’t help but think back to WWII when the British experimented with seeding clouds in order to induce heavy rain and, hopefully, wreak havoc with the German air force. Within a few days there was tremendous flooding in North Devon due to 250 times the normal amount of rainfall.

Let’s proceed quickly but cautiously, making sure that we don’t create new problems while solving our water shortages.

References

[1] Josh Clark, Why Can’t We Manufacture Water?, 2007
[2] Greg Peters, Environmental Assessment of Air to Water Machines, March 27, 2013
[3] Dr. Erik Leipoldt, The Whisson Windmill—Water From Air, Why Not?, 2016
[4] Matt Simon, Wanna Pull Water Out Of Air? Grab Some Ions Or A Weird Sponge, June 8, 2018
[5] Robert F. Service, This new solar-powered device can pull water straight from the desert air, April 13, 2017

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