Deserts may not have a lot of water like in rivers or lakes or aquifers but that doesn’t necessarily mean there isn’t a lot of water around somewhere. Many desert-dwelling plants and animals have adapted to extract water from the air itself, relying on fog that reliably shows up in deserts near warm oceans.
Fog is absolutely loaded with water, and the trick is to get it to condense out of the air. Humans accomplish this with giant mesh nets that the fog can condense on, with catch basins underneath to collect the runoff. What comes out is cool, clear, and perfectly pure, ready for drinking or irrigation.
Fog harvesting systems are currently in operation in more than a dozen countries worldwide, but MIT has devised a new mesh material that offers more than five times the efficiency of existing harvesters. This new stuff can suck 10% of the water out of coastal fog in windy areas, which translates into over three gallons per cubic meter of mesh, per day. It’s easy to scale (just put up more mesh), and the maintenance is essentially zero: collect the water when you need it, and occasionally brush dirt and bugs off of the mesh. It doesn’t cost anything to run, and will operate all by itself, more or less forever.
MIT figured out that the effectiveness of fog harvesters depends on three things: the size of the mesh fibers, the size of the spaces in the mesh weave, and the coating on the fibers themselves. By tweaking all of these parameters, the researchers were able to optimize for performance, resulting in “a mesh made of stainless-steel filaments about three or four times the thickness of a human hair, and with a spacing of about twice that between fibers.”
A team from MIT is currently camped out in the Atacama Desert in Chile (the driest place on Earth), where they’re testing a variety of different fog harvesting systems to see which work best where they’re needed the most. With enough harvesters, it might eventually be possible to meet the entirety of the water needs of the Atacama Desert through fog alone, which would be pretty amazing. Considering how simple, cheap, and reliable this technology is, we’re looking forward to seeing it in a lot more places around the world. Even in those places where it might not be strictly necessary to create clean water this way, it’s still hard to beat a fog harvester’s efficiency.