Biomimicry and Atmospheric Water Harvesting

This entry was posted by on Saturday, 8 August, 2015 at

Dew harvesting is ancient, and researchers are currently working on ways to improve it. Fog could also provide an important water source in areas with limited freshwater access. In addition to the fog-basking beetle covered in my last article, researchers are studying plants such as cacti and moss to learn how they harvest water in arid regions. One project that has received attention recently uses a metal mesh screen to collect water from fog; the metal mesh is more effective than the plastics that many fog collectors currently use. Researchers are studying other nature-inspired fog and dew collection methods as well.

Spiderwebs are good at collecting dew because their silk threads can change shape when exposed to water. This causes droplets to pool at points along the web. Studying the silk could be very helpful, since it could result in materials that attract water but quickly release it. A fog collector is more efficient when the water it collects rapidly falls down into the collection tank, allowing the collector to pull in more water. While the wind could shake a light mesh and release the droplets, the collector might not always have access to wind.

Another website illustrates how several types of plants collect water, including moss, horsetail, and cacti. The moss had an interesting water collection technique. Like the threads in the spiderweb, part of the moss structure changes shape when it collects enough water, automatically dumping it out onto the main body of the plant. The moss grows thin stalks with water collecting heads that collapse after collecting water, which can then rebound to collect more.

The moss and spider silk dew harvesting methods are very interesting, since it may be possible to incorporate them into mesh designs. A mesh with small projections, or stalks, could release water more effectively. A mesh that changed shape after collecting water and then returned to its original form could also be very useful. It might even be possible to combine both techniques in a dew harvesting device.

Velcro, the material that helps keep things in place, is another example of biomimicry. It was inspired by prickly burrs that effectively stick to clothing. But Velcro, or a similar material, might have a role to play in dew collection as well. Velcro is a plastic surface with very thin plastic loops attached. The thin loops seem similar to the moss stalks. A similar manufacturing process could create a material like the moss, a surface with thin plastic stalks and water collecting heads. So far it doesn’t seem like anyone has tried this, as manufacturing structures like moss stalks cost-effectively might be challenging, although a company like Velcro might know how to do it. A 3-D printer might also be useful here. Making the stalks and the water collecting heads out of the plastic that was similar to spider silk might also be effective. Of course, I haven’t tested this and don’t know if it would be as effective as a metal mesh screen. Either way, further research into biomimicry could result in better ways to collect dew and water from fog.

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