Planning a Desert Getaway? Bring Along a Beetle
By Paul Conley on July 22, 2014
If you’re thinking of wandering the desert any time soon, you may want to bring along an African beetle – just to be on the safe side.
Why? Well, these little guys have managed to stay alive in the in the Namib Desert of Southwestern Africa by literally pulling water from thin air. So they may have a thing or two to teach you about how to do the same.
Interestingly enough, a team of researchers has found a way to do just that: harvest water from even the driest desert air by building an array of carbon nanotubes that mimic the moisture-grabbing capabilities of the tiny Stenocara beetle.
Sehmus Ozden, a graduate student at Rice University, got the idea in a course on Biomimetic Engineering, which involves the replication of well-adapted structures of nature. A good example would be Velcro, which mimics the tiny burs on some plants. The self-cooling Eastgate Centre in Zimbabwe, which is modeled on the properties of termite mounds, is another.
Ozden learned how the Stenocara beetle captures water from the air. Each morning, it points its forewings, which are covered with nano-sized bumps, in the direction of the sea. The tips of the bumps are hydrophilic (water-loving) and the sides are hydrophobic (water-repelling). As a thin fog drifts across the desert from the sea, the bumps attract water droplets and send them down channels on the insect’s back to its mouth. Pretty cool, right?
Ozden reasoned that the he could create a “hygroscopic scaffold” of nanotubes that did essentially the same thing, and his professors backed his plan.
Ozden’s work is part of a broader trend in research and design to find ways to pull water from the sky. And there has been some remarkable progress made.
A billboard in Peru, for example, extracts some 25 gallons of drinkable water a day from the air through the use of filters and a condenser. Of course it doesn’t hurt that the humidity in Lima hovers around 98 percent. Meanwhile, industrial designer Arturo Vittori has invented giant vases that collect water from the air in Africa by using their unusual shape to promote condensation.
Ozden’s approach differs by favoring teeny, tiny, eensy, weensy tubes over big signs and vases. Working with Robert Vajtai, a senior faculty fellow in materials science and nanoengineering, Ozden and his team grew a nanotube “forest” about 1 centimeter thick. They coated the top with a hydrophilic polymer and the bottom with a hydrophobic polymer.
The resulting structure literally pulled water from the air and stored it between the two coatings. To drink the water the nanotubes capture, you simply squeeze the forest. Yes, you heard right. Just squeeze the array like a ripe orange.
It’s a pretty remarkable accomplishment: The array, which does not require an external energy source, was able to collect 80 percent of its weight in humid air and about 25 percent in extremely arid conditions.
The downside is the cost. Isn’t it always? Making nanotubes is currently an expensive process.
But as costs inevitably come down and it becomes possible to grow nanotube forests on a large scale, this innovation could become an efficient, effective water-collection device that could be deployed almost anywhere, as it does not require an external energy source. When you think of annual droughts in arid states like California, let alone people around the world whose lives depend on their next drink of water, nanotube forests could be a game-changer.
So next time you find yourself parched on nature walk or hike through a forest, give a tree a hug. Someday, it may give you a drink in return.
Paul Conley is a contributor to XPRIZE and an editorial consultant to brands, nonprofits and business publishers. He also writes about his unconventional approach to work, life and happiness at ABigFishinaSmallPond.com.