Scalable polymer films for sustainable moisture harvesting in arid environments | Hacker News Reader

Scalable polymer films for sustainable moisture harvesting in arid environments

nature.com

56 pointsoriggm23 comments

I don't buy the solve-water-shortage-at-scale promise. You need to heat it up to 60 °C to release the water which is bound to degrade the material.

Soft matter has excellent hygroscopic properties. But soft matter also has terrible stability.

One thing that's not mentioned is that local flora and fauna have adapted to these arid environments by being able to actually condense water out of the air for themselves. If you deploy this at scale what happens?

For example there are beetles that do this and the water drains straight to their mouth. [1]

As well, cactus needles serve this purpose by creating a Laplace pressure gradient. [2]

1 - https://en.wikipedia.org/wiki/Stenocara_gracilipes 2 - https://pubs.acs.org/doi/pdf/10.1021/acs.langmuir.5b03600

"The calculated vapor sorption rate of the SHPF is 1.65 L kg–1 h–1 at 30% RH, which indicates 1 kg of SHPF can capture 1.65 L of water vapor in 1 h, compared favorably among the state-of-the-art sorbent materials"

"The captured water in the SHPF can be released by >70% within 10 min through mild heating at 60 °C under a wide range of RH (Fig. 3b and Supplementary Fig. 15). This mild heating temperature is realized by introducing the hydrophilic thermoresponsive HPC with optimized molecular weight, concentration, and pH of the initial precursor (Supplementary Figs. 9–14 and Supplementary Table 2)42."

That sounds amazing to me if I understood it correctly.

Yeah some of it is a little confusing to comprehend. But, agreed, the numbers in this study are amazing. Higher than anything I've seen to date.

Crazy talk time. I wonder if we could have a national water grid that used air currents to push water inland from the seas. Then capture it with stuff like this.

It says this type of capture system works when RH<30%. Places like LV routinely see RH<.5%, for reference.

Good point. Still a nice upgrade from >70 or >90 systems that aren't helpful unless in specific conditions. Also promising on the materials side -- cheap

Isn't this exactly what happens in California, only the mountains right along the coast prevent that moisture from going inland very far?

> Crazy talk time. I wonder if we could have a national water grid that used air currents to push water inland from the seas. Then capture it with stuff like this.

Isn't this just basically describing rain? Air currents pushing water inland? A national water grid? That's just the water cycle mate.

I'm not sure pushing water vapor from the oceans and collecting the increased humidity from the air is energy efficient with mountains nearby, but the idea is really creative and kudos to those that came up with and might end up implementing it to solve water access issues.

They're talking about evaporating water and capturing the humidity up a hill. Not really rain.

Something like this. It’s probably a question of whether wind currents could reliably take some well positioned humidity from water outlets further inshore. Might be totally overcome by the mountains though.

It is not a crazy idea to develop infrastructure around such a goal though. Vast amounts of energy goes into aluminum production. So countries built huge power works for exactly that purpose.

The abstract broke my brain. Would appreciate a layman summary!

Their system uses a natural gel to absorb moisture out of relatively dry air of humidity levels of 15 to 30 percent. Other systems have shown success but only in high humidity of 70 percent and higher.

Thanks!

Any info on how much water, and if the gel "wears out"?

If you can grab drinking water out of the air, and wifi from the village Starlink, rural third world life can improve quite a bit!

Not sure on the wearing out, but agreed - these developments are encouraging to say the least.

Sure that's a great idea, but at the rate we're going, first world will be needing this tech too in a not distant future.

California, New Mexico, and Utah would like some water now thank you. I don't know if you consider them "first world" or not.

California is easy: just cut down all the almond trees, that will buy a few decades of runway.

I was being more nuanced.

California should be the world's leading pioneer on desalinization, but nope. So maybe they can figure this out instead? (not holding my breath)

I was being reductive. They should be on the forefront of water management. Didn't the state government cancel a few very large desalination plants recently? After Lakes Powell and Meade and the Colorado River dry up and after the snow caps melt and while precipitation stays reduced and the aquifers dry up and sinkholes appear, what do you think will happen to California agriculture and Silicon Valley? The lush valley turns into desert. How times change ..

In the ice caps melt situation, I very much doubt that California will be alone in the needing of fresh water

Yikes, I meant to say the snow caps in the mountains. I've changed that now. But yeah, ice caps melting are really a question of when rather than if at this point sadly.

does California still have snow caps?

Last time I was there it did. But now, I guess not :(.

https://news3lv.com/news/local/lake-meads-source-hows-the-sn...

Reply on news.ycombinator.com