Namib Beetle inspires new 'fog harvesting' research


April 26, 2011

Mesh being tested for use on fog-harvesting devices by Shreerang Chhatre and colleagues at MIT (Photo: Patrick Gillooly)

Mesh being tested for use on fog-harvesting devices by Shreerang Chhatre and colleagues at MIT (Photo: Patrick Gillooly)

For years, people living in high-altitude or coastal arid countries have been collecting drinking water by harvesting fog. More specifically, they've mounted pieces of fine netting over top of containers, left the setup overnight, then collected the fog droplets that got caught in the net and rolled down its fibers into the container. While it might sound like a rather insubstantial way of acquiring water, under the right conditions it can yield a surprisingly large amount of liquid. Now, a chemical engineering graduate student from the Massachusetts Institute of Technology (MIT) is looking to improve on the technique.

Shreerang Chhatre was inspired by the Namib Beetle, an insect that collects water droplets on bumps on its back, then drinks them when they roll down to its mouth. His "fog harvesters," like those created by other scientists, use a mesh panel in place of a net. Even solid materials such as plastic sheeting will work, although they can create wind currents that carry some of the moisture away.

In tests of existing fog harvesters, some have been able to collect one liter (about a quart) of water per meter of mesh, per day.

Chhatre is trying to boost that output by refining the materials that the mesh is made from, attempting to strike a balance between hydrophilic materials that attract water droplets, and hydrophobic materials that then send them on their way down into the collection container. The Namib Beetle employs a similar strategy, with hydrophilic bumps that droplets stick to, and hydrophobic channels that allow those droplets to slide down to its mouth without being absorbed along the way.

Much as improving the amount of water obtainable from fog harvesters is a technical problem, it's also a social one – most of the potential users likely couldn't afford such a device. To that end, Shreerang is hoping that people in developed nations might also start using them, simply to offset their consumption of fresh water from traditional sources. The more units that are sold to such First World consumers, the lower the prices could be for Third World recipients, and the more accessible the technology would become.

Source: MIT

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

The problem with collecting fog is that the process also collects the air pollution that\'s dissolved in or mixed with the fog. Who\'d want to drink that? Certainly no one in a first world city.



You breathe more of that stuff every day than you would drink from a liter of condensed water.

The real problem is that a liter of water is nothing to people in the US. Average water use is hundreds of liters a day per person. Sad to say, none of us are going to pay for expensive, bulky fog catchers when we can just get it from the tap or worse, just stop by the store and pick up a bottle. Convenience trumps greenness.

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