Fog is little more than an earth-bound cloud. When I picture fog harvesting, I have an image of people moving quietly through dense fog, using loose linen bags to scoop against the water-laden air around them. But why would anyone harvest fog? It’s not as if enough of it would ever stay in the imaginary bags to leave behind a harvested area of clear, sunny terrain.
When we talk about design engineering, it’s usually with a specific goal in mind. But sometimes the real goal isn’t apparent until the first goal has introduced a design idea. This was true of fog harvesting, which did not begin with people gathering fog in sacks to little purpose.
Fog harvesting, the gathering of moisture from fog, has been around for millions of years, at least when it comes to plants. Some ferns, redwoods and berry plants absorb up to half their water intake from the moisture in fog – and that’s not from moisture that accumulates on the ground. They absorb the moisture directly into their leaves, or from the drops that collect at the base of stems.
The Meteorological Service of Canada (MSC) was studying the particle constituents of fog in Quebec when it created fog harvesting equipment in the 1980s. Basically, they built a stationary canvas sail with a collecting trough at the bottom – fog coalesced on the material and dripped down into the trough for examination. This technique was then re-purposed for a reforestation project in Chile, with the fog harvesting sails redesigned to irrigate hillside seedlings in a denuded area that had once been cloud forest.
What happened to the fog water, though, indicated an entirely different need: the local villages of the area suffered from water scarcity, and wanted the water gained from the fog harvesting to be redirected from the reforestation project to the local inhabitants.
And out of this somewhat messy, haphazard path of discovery, the idea of fog harvesting for people in water-scarce areas came about.
These days, there are a few non-profit organizations focused on various collection and distribution methods, including the International Organization for Dew Utilization (OPUR), which sounds like a dream company out of a fog fairytale, but which is a functioning entity working to combat water scarcity.
Looking at the design telescope from perspective of the end result, the idea of catching ephemeral water droplets seems obvious.
There are still issues to be resolved – how to keep the passive catchment and distribution systems clean, how to gather the maximum amount of moisture.