Materials

Cheap gel film pulls buckets of drinking water per day from thin air

Cheap gel film pulls buckets of drinking water per day from thin air
A sample of the new gel film, which can pull huge amounts of drinking water out of thin air
A sample of the new gel film, which can pull huge amounts of drinking water out of thin air
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A sample of the new gel film, which can pull huge amounts of drinking water out of thin air
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A sample of the new gel film, which can pull huge amounts of drinking water out of thin air
The gel film can be cut and molded into whatever shape is needed
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The gel film can be cut and molded into whatever shape is needed
The full test device, working to produce drinking water from the air
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The full test device, working to produce drinking water from the air
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Water scarcity is a major problem for much of the world’s population, but with the right equipment drinking water can be wrung out of thin air. Researchers at the University of Texas at Austin have now demonstrated a low-cost gel film that can pull many liters of water per day out of even very dry air.

The gel is made up of two main ingredients that are cheap and common – cellulose, which comes from the cell walls of plants, and konjac gum, a widely used food additive. Those two components work together to make a gel film that can absorb water from the air and then release it on demand, without requiring much energy.

First, the porous structure of the gum attracts water to condense out of the air around it. The cellulose, meanwhile, is designed to respond to a gentle heat by turning hydrophobic, releasing the captured water.

Making the gel is also fairly simple, the team says. The basic ingredients are mixed together then poured into a mold, where it sets in two minutes. After that it’s freeze-dried, then peeled out of the mold and ready to get to work. It can be made into basically any shape needed, and scaled up fairly easily and at low-cost.

The gel film can be cut and molded into whatever shape is needed
The gel film can be cut and molded into whatever shape is needed

In tests, the gel film was able to wring an astonishing amount of water out of the air. At a relative humidity of 30 percent, it could produce 13 L (3.4 gal) of water per day per kilogram of gel, and even when the humidity dropped to just 15 percent – which is low, even for desert air – it could still produce more than 6 L (1.6 gal) a day per kilogram.

That’s a huge improvement over other water harvesters we’ve covered over the years. The highest previously was 8.66 L (2.3 gal), but that was in air with much higher humidity. Others have topped out at 5.87 L (1.55 gal) at 30 percent humidity, or as little as 1.3 L (0.3 gal).

And the new gel film's efficiency could be improved even further, the team says, by creating thicker films, absorbent beds, or other array formations of the material. Perhaps most importantly, the material is extremely inexpensive to produce, costing as little as US$2 per kilogram. That’s another major factor in scaling up the technology and getting it to remote areas and developing countries, where it’s needed the most.

The research was published in the journal Nature Communications.

Source: UT Austin

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15 comments
15 comments
Gabe Ets-Hokin
Is the film reusable, though? Does it degrade or dissolve from the water?
c2cam
Personally I think humankind needs to look at controlling our population so we don't outsize the resources the planet has to offer. At some point there will be no more stones to turn over. We also have to think of all the flora and fauna on the planet, not just ourselves. I also fear that a technology such as this could be used on a grand scale which I wonder how that would affect rain patterns since we would be extracting moisture from the air which wouldn't condense into rain.

Methinks it would be better to focus on desalinating ocean water instead?
freddotu
Gentle heat to release the water? In arid climates, one must consider that solar energy is likely to provide as much gentle heat as needed. It seems like a fairly economical combination. I'd like to know more about durability and longevity.
paul314
How much area is a kilogram? From the looks of it, the layers are maybe a couple millimeters thick, and if it's a foam the density is going to be less than than that of water. Back of the napkin says at least a square meter per kg, so for large-scale production you'd need big sails or something.
guzmanchinky
This is INCREDIBLE. I would love some as an emergency kit.
Karmudjun
Nice write up - and in reading the source article, I notice a missing piece of information isn't provided in the source article either. Why you didn't mention the caveat is beyond me Michael as most articles of yours mention incomplete aspects.
This new gel structure impregnated with Lithium Salts sounds great - but what ~100 um thickness gel size is required for the maximum water collection? The kg weight / water collected without any density information is PRACTICALLY USELESS. Other than that Michael, good article.
Ed
I'd love some of this for backpacking trips! It's a huge hassle to lug water around.

As for c2cam's comments, there are several misconceptions. First, not everyone lives on the coast, so desalinization is not practical. Second, population control has nothing to do with water production. Third, water extraction from the atmosphere is used in mostly relatively arid regions that don't get much rain anyway, and the very small amount of water pulled from the air isn't going to affect rain patterns at all.
Christian Lassen
Gotta respond to c2cam, there are still so many stones left to turn over. We are more likely to crowd ourselves out and stifle our own population growth purely out of self-loathing than due to resource limitations. We're already set to have a shrinking population in 50 years and that's not even due to any natural limitations except our own self-hatred of our species and each other. We have more abundance per person in the history of the world and we're still barely scratching the surface for available resources on this planet, but too many people who hate other people are eager to call for a population limit.

I think this is pretty neat stuff and hope that it works out.
vince
Perhaps they can coat the onside of solar cells with the substance to provide gentle heat to squeeze water out and solve two problems with one product.
aksdad
Excellent improvement in efficiency. What a great innovation! @c2cam, humans are in no danger of outstripping Earth's resources on a global scale. Locally, poor resource management has caused environmental problems in places, but they can be (and have been) fixed with better resource management. Birth rate has declined to below replacement in most of the developed world. As nations rise out of subsistence level economies they become wealthy and their birth rates naturally decline. Even if we reach a global population of 10 billion, which we may not, the planet has more than enough resources to sustain the population if managed well, which most developed countries do.
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