The Fog Catchers

Janice_Kaspersen_Erosion_Control-Blog

In the 1946 short story “Miss Winters and the Wind,” a woman tries to capture the wind in a bedsheet; the results aren’t quite what she’d intended. Today, a small farming community in Chile is having better luck catching fog in a net.

As we face the possibility of increasingly longer periods of drought, the question of what to do about it—how to bring more water to parched regions—becomes a more pressing one. Desalination is one possibility, but it’s expensive and limited in how much of the problem it can solve, as Water Efficiency’s editor Laura Sanchez discusses here. Capturing water for reuse—either through aboveground means like rain barrels on a small scale or damming rivers on a larger one, or by infiltrating water to replenish aquifers—is an obvious route.

If your topography is just right, though, there’s another option: catching water droplets in a net, as is happening in parts of Chile’s Coquimbo region. Strong coastal winds and a near-shore mountain range provide ideal conditions to harvest fog. It’s a simple concept: The nets capture moisture and send it, via pipe, to some sort of storage container. Right now, as this article describes, the community of Los Tomes is deploying three nets, each 646 square feet, to capture on average 140 gallons a day, which is mostly used to water livestock. Other communities are using fog capture to irrigate olive trees and, in one case, to produce artisanal beer (the fog nets, say the beer producers, are a great selling point).

The region has been in the midst of a drought for about 10 years. There are more than 40,000 hectares of land with similar conditions for catching fog, and it’s estimated that if nets were placed everywhere they could be, they could bring in as much as 1,400 litres per second. That would supply enough drinking water for the livestock as well as all the people.

Why isn’t it being done on a larger scale? Nearly 30 years ago, a village north of Los Tomes managed to set up nets and capture 8,000 gallons of water a day, but it didn’t last long. For one thing, the nets are expensive and must be regularly maintained and replaced. Back then, it wasn’t considered worth the effort and expense, but if the drought continues, that might change. A government effort is underway now to fund a new project.

It’s possible that the nets will run into objections because they interfere with birds or block views—as has been the case with some wind farms in the US. And of course this method will work only in very limited geographical conditions with the right combination of wind, fog, and mountains; the process is also being used in parts of Morocco and Tanzania, for instance. A German company called CloudFisher is producing what it claims is a low-maintenance fog net that’s being used in some areas, and a Canadian company called FogQuest does something similar.

Have you seen a fog net in action? What other promising water-capture technologies are you aware of? EC_bug_web

Comments
  • William Hamel.

    Been doing it in Baja California for years, same situation on the coast inland breeze/fog. Great farming area and shortage of water.

    Reply

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