Fog-catching technologies have been used for centuries to gather moisture in deserts; we even explored the possibilities for mitigating the effects of drought earlier this year. But the issue with introducing them into our cities is a matter of scale: fog catchers need to be particularly large to catch a significant amount of water, and it's not like we can go draping the city in tarps just to harvest a few trickles.
But maybe it's not giant fog-catching curtains that need to be erected over our drought-plagued cities. Maybe we should install micro fog-catchers on each of our porches. That the idea behind this concept by IDEO which is inspired directly from nature's best fog catcher — the one found in the back of the Stenocara beetle of the Namib Desert.
The beetle carefully angles itself so that its shell is a precise 45 degrees facing the wind — the most efficient angle to maximise its surface exposure to the precious moisture-laden breeze. Spiny electrostatic bumps extract particles of moisture from the breeze, consolidating them into tiny droplets between the protective bumps. Thirty kilometer per hour winds gust and the small droplets start to buckle and deform, sticking like glue to the shell. Ten minutes later the surface tension of a droplet gives way, rolling down the beetle's waxy hydrophobic troughs towards its mouth.
Using the beetle's shell as a model, IDEO design director Will Carey and a team including Scott Paterson, Dav Rauch, Aaron Wanch and Francois Rybarczyk came up with an at-home fog collector which can easily be installed on the exterior of any San Francisco residence.
It's a tiny little thing, but Carey says it harvests enough water to make his coffee every morning.
They also designed a portable version which can be moved around to capture maximum fog.
Carey then prototyped a roof unit for his apartment building which he says can gather water to be used for laundry or toilet flushing.
Fog catchers won't work everywhere in California, but in many coastal cities like San Francisco it's too simple and obvious of an idea not to try. Like the new ways we're looking at collecting energy via solar panels or capturing groundwater on our properties, the better solution for the future is often not a grid-wide technology — rather, it's a block-by-block fix.
All photos by IDEO; Carey's rooftop panel fog catcher by sf environment