Posted on 05/20/2021 7:41:42 AM PDT by Red Badger
Images of representative fabricated PVA/PPy gel micro-tree array. Scale bar: 1 cm. Credit: California Institute of Technology
_____________________________________________________________________
Tiny structures inspired by the shape of cactus spines allow a newly created material to gather drinkable water from the air both day and night, combining two water-harvesting technologies into one.
The material, a micro-architected hydrogel membrane (more on that later), can produce water through both solar steam-water generation and fog collection—two independent processes that typically require two separate devices. A paper about the material was published in Nature Communications on May 14.
Fog collection is exactly what it sounds like. At night, low-lying clouds along sea coasts are heavy with water droplets. Devices that can coalesce and collect those droplets can turn fog into drinking water.
Solar-steam generation is another water-collection technique. It works especially well in coastal areas because it is also capable of water purification, though it works during the day instead of at night. In the method, heat from the sun causes water to evaporate into steam, which causes water to evaporate into steam, which can be condensed into drinking water.
Because the two technologies operate under such different conditions, they typically require different materials and devices to make them work. Now, a material developed at Caltech could combine them into a single device, working to generate clean water 24 hours a day.
Images of an individual representative tree micro-topology. Scale bar: 1 mm. Credit: California Institute of Technology
____________________________________________________________________________
"Water scarcity is a huge issue that humanity will need to overcome as the world's population continues to grow," says Julia R. Greer, the Ruben F. and Donna Mettler Professor of Materials Science, Mechanics and Medical Engineering and Fletcher Jones Foundation Director of the Kavli Nanoscience Institute. "Water covers three-quarters of the globe, but only about one half of one percent is available freshwater."
Greer has spent her career developing micro- and nano-architected materials; that is, materials whose very shapes (controlled at each length scale, nanoscopic and microscopic) give them unusual and potentially useful properties. In this case, Greer collaborated with Ye Shi, formerly a postdoctoral scholar at Caltech and now a postdoctoral scholar at UCLA, to create a membrane of arrayed tiny spines that resemble Christmas trees but are in fact inspired by the shape of cactus spines.
"Cacti are uniquely adapted to survive dry climates," Shi says. "In our case, these spines, which we call 'micro-trees," attract microscopic droplets of water that are suspended in the air, allowing them to slide down the base of the spine and coalesce with other droplets into relatively heavy drops that eventually converge into a reservoir of water that can be utilized."
The spines are built out of a hydrogel; that is, a network of hydrophilic (water-loving) polymers that naturally attract water. Due to their tiny size, they can be printed onto a wafer-thin membrane. During the day, the hydrogel membrane absorbs sunlight to heat up water trapped beneath it, which becomes steam. The steam then recondenses onto a transparent cover, where it can be collected. During the night, the transparent cover folds up and the hydrogel membrane is exposed to humid air to capture fog. As such, the material can harvest water from both steam and fog.
In an operation test conducted during the night, samples of the materials ranging from 55–125 square centimeters in area were able to collect about 35 milliliters of water from fog. In tests during the day, the material was capable of collecting about 125 milliliters from solar steam.
Porous structure of gel matrix. Credit: California Institute of Technology
________________________________________________________________________
The exact design of the membrane was created using the design program SolidWorks.
The hydrogel itself is a polyvinyl alcohol/polypyrrole (PVA/PPy) composite gel, a non-toxic and flexible material used in numerous applications including in capacitors, wearable strain and temperature sensors, and batteries.
To fine-tune the design of the micro-trees, Greer and Shi worked with Caltech's Harry Atwater, Howard Hughes Professor of Applied Physics and Materials Science; and Ognjen Ilic, formerly a postdoctoral scholar at Caltech and now Benjamin Mayhugh Assistant Professor of Mechanical Engineering at the University of Minnesota.
Using computer modeling, Ilic computed the heat distribution within the micro-trees to help define the size and shape that would be most effective at drawing water from the air. With this successful proof-of-concept, the team now hopes to find a private partner capable of commercializing the technology for water-scarce regions.
"It is really inspiring that a relatively simple hydrophilic polymer membrane can be shaped in a morphology that resembles cacti spines and be capable of tremendous enhancement in water collection. I guess evolution really works," Greer says.
The Nature Communications paper is titled "All-day Fresh Water Harvesting by Microstructured Hydrogel Membranes."
Explore further
Video:
Tiny shape-shifting polymers developed for potential medical applications
More information: Ye Shi et al, All-day fresh water harvesting by microstructured hydrogel membranes, Nature Communications (2021). DOI: 10.1038/s41467-021-23174-0
Journal information: Nature Communications
Provided by California Institute of Technology
Luke Skywalker’s uncle made a living doing this. Of course, that was a long time ago.
In a galaxy far, far away...
If something like this would work in non-coastal, indoor, humid climates, they would be great for improving indoor comfort and reducing AC loads.
Moisture farms on Tatooine coming soon. I think we all know who will be playing the part of the Empire...
If done large scale would this effect subsequent rainfall downwind like the Midwest?
That is considerable output for such a small area...
About 150 ml (five ounces) produced from a 4 inch square collector, in one day?
Probably ideal conditions, but, that is what is implied by the paper.
In the method, heat from the sun causes water to evaporate into steam...
~~~~~~~~~~~~~~~~~~~~~~~~~~
I’ll bet he means evaporates into water vapor, not steam.
Now, make that into a mask and you recycle moisture from your own breath.....................
Both of you have the essence of where I think this technology will have its greatest applications - over 100 years from now in some “off world” human “encampments”.
Midwest moisture comes primarily from the Gulf of Mexico.
The Rockies essentially dry the air before it reaches the midwest............
There is no scarcity of water. There is a scarcity of of political will to do good things for the citizens.
Fix water scarcity.
1. Ocean water to desalinization facilities along the coast.
2. Pipelines covered in solar collection materials to be converted to electricity to run pumping stations along the way.
Route the pipelines to places where water is scarce. Problem solved.
It really is that simple. With fresh water, new economies are created for food production and export.
Again, it is only political will that stops this from happening.
None was mentioned in the novel, that I recall.
The human body uses water to rid itself of waste heat. It is impossible to retain the water and get rid of the heat, unless you use an outside energy source to do it. Then you have to get rid of the waste heat from the energy source...
Dune was far more fantasy than science fiction.
Too bad he’s too busy wasting time with his friends while at Tosche Station to pick up some power converters.
Nature has always been doing this.
You ever look at the stalks and leaves of a squash plant? A large leaf held up by a U shaped stalk. Dew collects on the leaf, then runs down the U channel of the stalk to the area where the roots are.
Some other plants do the same.
the big invention likely to come this decade is seawater desalination cheap enough for agriculture. Israel and Singapore routinely desalinate seawater for about %500@acre foot. But there are reports that both are moving toward $400@acre foot. You can grow all fruits and vegetables profitably—but not field crops—at $300@acre foot.
The root zone of a tree usually does not extend beyond the drip zone of the branches...................
Fix water scarcity.
1. Ocean water to desalinization facilities along the coast. 2. Pipelines covered in solar collection materials to be converted to electricity to run pumping stations along the way.
Route the pipelines to places where water is scarce. Problem solved.
It really is that simple. With fresh water, new economies are created for food production and export.
Again, it is only political will that stops this from happening.
You post a common fallacy.
Just because a thing is technically possible does not mean it is economically possible.
Economics rule. Political entities could do what you say. It would simply bankrupt the countries doing it, making far more people poor than it takes out of poverty.
There are much simpler solutions to household drinking, washing, and cooking water.
To use your "solution" for industrial purposes or agriculture, is far,far, from economic.
Yep. Kids. Whadayagonnado?
I was into power converters when I was a teen. Then I grew up and discovered girls.
Yes it was. Pumps in the feet soles generated the energy needed to operate the suits as the wearer walked............
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.