A better fog trap may be a linguistic twist on an old marketing expression but it’s a simple, real, and effective solution to drought in the Atacama Desert in Chile.
The Atacama Desert, which stretches 1600 kilometers along Chile’s west coast, and covers an area of approximately 128,000 square kilometers, is often called the driest place on earth. Estimates of annual rainfall range from 15mm to 3-4mm with some weather stations reporting no rainfall….ever. One authority claims the desert received no significant rainfall from 1570 to 1971. Geologic evidence suggests the area has been that arid for 200 million years.
The desert has been used by NASA to replicate conditions on Mars, ahead of its planned expeditions to the planet, and many space movies have been staged there.
As a result, water in the Atacama Desert is at a premium, and a matter of life and death, like no other place on earth. Enter the fog trap.
The cold Humboldt Current which runs off-shore from the Desert, produces thick fog that billows across the land. In the 1960’s, that fog was harvested by an invention called a fog trap. The fog causes no rainfall, but it can be captured, and drinkable water extracted.
The early version of the fog trap uses a polymer-mesh screen held in a metal frame, rather like the screen door on your house. Fog droplets adhere to the mesh, attract more droplets and then, when they are big enough, they run down the screen to a collection trough at the bottom. A typical 40 square meter screen (10m wide by 4m high) can collect around 200 liters of water a day. That provides enough drinking water for about 60 people. It costs less than US$1,000 to build, and lasts about ten years. A great invention, and a life sustainer for Atacama Desert residents.
All technology can be improved, however. The trick is to improve it without making it complicated, and without the end result costing fortune, which would obviate the whole effort.
Dr. Stachewitz and Mr. Ura of the AGH University of Science and Technology in Krakow, Poland have discovered that, if the mesh is slightly charged electrically, it will attract and hold more fog droplets. Initial experiments involved metal plating of the mesh proved too expensive, but modifications to the mesh-production process proved simple and effective, with no increase in production costs. This new mesh will collect 50% more water than the original mesh.
Prototypes are currently being turned into production units that will be sold to the people of the Atacama.
It is nice to report a technological success story that doesn’t create more problems than it solves, that uses natural processes, and virtually no negative environmental impact. The commercial use of this new technology is limited to areas like the Atacama, which are few and far between. I can only say we should be grateful for that. At least it will not be worthwhile for some conglomerate that sells desalination plants, for example, buying up the technology and killing it. A process that happens far too often.