Posts Tagged biomimicry

Biomimicry and Atmospheric Water Harvesting

Posted by on Saturday, 8 August, 2015

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.

Biomimicry

Posted by on Thursday, 11 March, 2010

I have seen a lot of technologies based on nature recently. The axiom always said not to reinvent the wheel, so why would we attempt to do this when creating sustainable business? Anything that powers a living organism has been shaped by evolution over many years. Because of the competitive pressures in any environment, superfluous elements are swept away. Even things that seem like they have no purpose like the peacock’s feathered tail and the songbird’s song are necessary so that the creature can attract potential mates. Resources are limited, so many animals have evolved to become efficient in surprising ways. Here are a few companies that are attempting to harness these natural processes to gain a competitive advantage.

On the White House energy blog, Secretary Steven Chu mentioned some of the companies that received the ARPA-E grants to help them research new technologies. One of the companies he mentioned was Sun Catalytix. They got a $4 million grant to research an energy process which is similar to photosynthesis. All of the other energy sources are originally powered by the sun, and it will continue to be the main source of energy in the future. Photosynthesis has beaten out all of its competition so far, so it definitely appears to be the ideal place to start looking for a new direction.

We have the advantage of not needing to power the other parts of a tree, such as organs used for defense and reproduction, and so we can focus in on the conversion of as much energy as possible from the reaction. The Sun Catalytix site links to which gives a little more information on the technology. This article talks about the catalyst forming and operating in neutral water under ambient conditions. It also mentions that the catalyst is formed from common materials; many efficient solar power devices require the use of rare earth metals, and we could quickly run out of them if we tried to set up many large scale power plants using rare earth metals. Mining is also a large potential issue with solar technology as extracting metals often causes a lot of damage. Biomimicry reduces a lot of the problems caused by mining, as a tree does not need to destroy an entire mountain to be able to gain its nutrition from the sun.

The biggest issue I see with biomimicry is the complexity of the molecules used in the new technologies. A lot of traditional chemistry reactions can be explained very simply, you have a process like H2 + O2 → 2H2O. Even the other reactions like burning petroleum are not much more complex, you have a reaction like CH3-CH2(n)-CH3 + O2(excess) → CO2+H2O. There are some contaminants like nitrogen and sulfur that are burned and create smog, but that’s how the main reaction goes. For a biological reaction you’re attempting to mimic molecules that are a lot more complex. Look at the structure of Chlorophyll, it is a lot harder to model the reactions of a molecule this complex. Fortunately, with the software we have available now it is becoming much easier to calculate the molecular interactions, and once the research is complete building additional solar plants based on biomimicry should be a lot cheaper than having to dig up rare earth metals.