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Mining Fog
Thu Aug 12, 2004
Listen in RealAudio 
Mining fog may sound like an impossible task. But for residents of the Northern
Chilean fishing village of Chungungo, it provides their main supply of drinking water.
Hi, I'm Bryan Yeaton and this is The Weather Notebook.
For years, water had been trucked into the village at a cost of about 10 percent of total
personal income. That is, until Canadian scientist Robert Schemenauer addressed
the problem.
After watching trees collect water from clouds and fog, Schemenauer realized he could
imitate these great natural fog collectors to mine water from the air.
Because fog droplets are so small and drop very slowly, they travel nearly horizontally,
even in the lightest breeze. Since they don't fall like rain, they can't be caught in a
bucket.
A good fog collector requires large, vertical mesh panels -- to imitate tree branches
and leaves -- through which the fog droplets can drift. As they drift through the mesh,
some droplets strike the weave and trickle down the panel. The amount collected
depends on the collector's surface area, its efficiency and the wind speed.
While Northern coastal Chile is extremely dry -- often going many years without rainfall
-- it does experience frequent sea-fogs in the coastal hills, even during the dry season.
In the initial Chungungo setup, 50 large collectors, each covering 48 square meters,
produced a daily average of about 11,000 liters of water, 33 liters per day per villager --
significantly more than the average per capita need of 14 liters daily. Approximate price
for one such collector, $5,000 to $10,000.
The project's success has lead to similar projects in other countries, including South
Africa, the Dominican Republic, Israel, Cape Verde and Canary Islands, and Nepal.
The Weather Notebook is a production of the Mount Washington Observatory and
sponsored by Subaru of America and the National Science Foundation.
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