- Two-thirds of the world’s population faces an extreme water shortage at least one month a year. Many of these places are dry, arid deserts with no reliable source of fresh water – other than fog, that is.
- But fog capture isn’t as easy as you might think, at least for us humans.
- The Namib Desert beetle, on the other hand, has practically perfected the art.
- Here’s how scientists are creating technology based on the beetle’s exoskeleton that could help end water scarcity.
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Following is a transcript of the video.
Narrator: Here’s a riddle for you, a man is standing in the desert. He’s thirsty, parched, and surrounded by fresh water but he can’t drink. Why? He’s surrounded by fog. This isn’t actually a riddle, it’s a real problem scientists have been trying to solve for years. And the solution might just be this little beetle. It might not look like much, but it can pull water out of thin air.
Two-thirds of people on Earth face an extreme water shortage at least one month a year. Half a billion don’t have enough water year-round. And these numbers are only expected to rise as climate change takes its toll. But what many of these regions lack in traditional water sources, they make up for in fog, like the Namib Desert. It’s one of the oldest and driest places in the world. Depending on how far you are from the coast, rainfall averages about a half-inch to two inches per year. But it’s what we would consider a fog desert, a place where fog is the main water source for plant and animal life, like the Namib Desert beetle.
At first glance, this group of beetles would seem to be really bad at capturing fog. It’s tiny, it’s round, and our current fog-collecting technology looks nothing like it. Fog meshes right now are based on leaves and blades of grass, and their efficacy is determined by this complicated formula. Where these two basically confirm that fast winds, big droplets, and slender targets across a large area are the best conditions for collecting. And this one represents the mesh’s ability to drain the collected droplets into a reservoir without clogging.
So, based on the formula, the Namib Desert beetle shouldn’t be able to do what it does. Since, you know, beetles aren’t made of mesh. And yet, when fog rolls in, the beetle climbs to the top of a dune and fog basks, leaning down and into the wind. Water droplets collect on its back and roll down to its mouth. As simple as that sounds, it’s very literally like trying to catch a cloud and pin it down.
Hunter King: If you wave your fingers through mist, you don’t see just a path where your fingers were and all the water collected. It just flows with the air, right through them.
Narrator: But the beetle manages to do what we cannot. The secret is in its exoskeleton. And it’s very much a secret.
King: We are far away from that still, or we’re getting closer.
Narrator: A lot of research has been done on how the water moves to the beetle’s mouth, but almost none has covered how the droplets get there in the first place. Hunter King and his team tried to find the answer but hit an unexpected bump in the road. The original beetle that scientists started researching first had exactly that, bumps on its exoskeleton. And those bumps were theorized to have an impact on the efficiency of fog collection. But…
King: It turns out the beetle that has the bumps is not one of the fog-basking beetles.
Narrator: King and his team decided to move forward with their experiment anyways. In the lab, they 3D-printed spheres and cylinders with various surface textures, smooth, ridged, and bumpy. They then put the spheres in a foggy wind tunnel. Turns out the sphere with one millimeter bumps captured fog 2.5 times better than the smooth sphere.
King: If you add ridges that are maybe a little bit like the beetle that we found is the fog basker, you go up to something like a factor of two, so it’s still not small.
Narrator: Further research in partnership with computational fluid dynamics experts at the University of Illinois, zoomed in even closer. They developed a computer model that tested droplets’ ability to bump into a surface. Tiny water droplets have very little inertia, and have to squeeze a film of air out of the way before making contact. The model found that the less squeezing droplets have to do, the more that bump into the surface, which is what you should get with rougher textures. These tiny details are important for harnessing and recreating these properties into a usable technology.
King: If we understand the beetle’s game, then we can play it differently towards greater effect.
Narrator: Even a slight increase in efficacy could improve the lives of people who rely on current fog capture tech. And we’re not just talking drinking water here, fog capture can open agricultural doors, allowing people to raise more crops and livestock. Identifying these properties is one thing. But once scientists are able to harness them, engineers should be able to design all sorts of fog collectors. Stand-alone fog-collecting structures, for sure. But they could also use the material to coat existing objects to turn anything into a fog collector.
King: There have been proposals about modifying tents, say for refugee camps, if we were to say that these tents are going to be in a place where there is enough wind-driven fog, then you could make bumps on the surface of it.
Narrator: Both King’s semi-accidental bump discovery and the still-unknown qualities of the actual fog-basking beetle could help solve the riddle, giving that man in the desert a better way to drink. And, potentially, ending water scarcity for good.
EDITOR’S NOTE: This video was originally published in August 2020.