6 ms·

> a new class of nanostructured materials that can pull water from the air, collect it in pores and release it onto surfaces without the need for any external e

> a new class of nanostructured materials that can pull water from the air, collect it in pores and release it onto surfaces without the need for any external energy As a similar comment note, it's like a high tech Dehumidifier bag. https://www.amazon.com/Wisesorb-Moisture-Eliminator-Fragrance-Dehumidifier/dp/B088N8DGP6?th=1 https://www.amazon.com/Wisesorb-Moisture-Eliminator-Fragranc... The bags have Calcium Chloride and absorb water from unsaturated air and make small drops of water. It's obvious that they get depleted, and to use them again you must buy a new one or boil all the water to get the crystals again. In this new material, the droplets are attached to the material. To remove them you must use energy. They don't just drop to a bucket bellow the device magically. You can't use it to "harvest" water without energy. You can sweep the droplets with a paper towel, but now to remove the water from the paper towel you need energy. > With a material that could potentially defy the laws of physics in their hands This does not break the laws of physics. It would be nice that the PR department of the universities get a short course explaining that if they believe the laws of physics are broken, then they must double check with the authors and then triple check with another independent experts. Tech journalist should take the same course. Note that the bad sentence and the misleading title is from the university https://blog.seas.upenn.edu/penn-engineers-discover-a-new-class-of-materials-that-passively-harvest-water-from-air/ https://blog.seas.upenn.edu/penn-engineers-discover-a-new-cl...

Evidlo 1y ago
When a publication I was involved in got a university PR piece, they were in direct communication with us
- Y_Y 1y ago
  Amusingly, I have the same experience as you and GP. Thee university wants to hear what the researchers have to say, but subsequently they decide independently what they're writing, strict scientific honesty be damned.
  - B1FF_PSUVM 1y ago
    Honesty pays no bills for professional liars. Like diplomats, they're sent abroad to lie for their university, and the university president cries all the way to the bank for the sins of his hirelings.
- beloch 1y ago
  University PR folk are sometimes quite scientifically illiterate. Their job is basically marketing. They need to turn an esoteric, jargon heavy, and heavily qualified paper into a hype piece that the money people can understand. Everything must be a ground-breaking, world-shaking, all-time first. They sometimes make dubious claims no matter how many times you tell them not to. Ultimately, they report to the university's money people and not to researchers. If you want science, read journals. If you want to see who is likely to get more money, read university PR releases.
- wenc 1y ago
  I've observed the same. University science PR pieces are usually unreliable -- they are optimized toward generating buzz than scientific accuracy. They usually link to the actual science papers, but the prose is usually a stretch. Even in this case -- "defying the laws of physics" is sensationalist narrative manufacturing. The real claim is actually more moderate, and the research is not really close to commercial yet.
wenc 1y ago
It's research-in-progress, but I think the promise is slightly different from dehumidifier bags (also in other parts of the world, Thirsty Hippos [1]) which are single use. You're correct in that: (1) it doesn't break the law of physics; (2) to remove the droplets, you still need energy. But it sounds like if the droplets are moving to the surface, the energy needed to release the droplets could be far lower than most active dehumidification methods (e.g. Peltier junctions). [1] Thirsty Hippos -- which are very effective in small spaces. https://www.amazon.sg/Thirsty-Hippo-Dehumidifier-Moisture-Absorber/dp/B0713TGZD6 https://www.amazon.sg/Thirsty-Hippo-Dehumidifier-Moisture-Ab... Basically a supercharged silica gel.
- EA-3167 1y ago
  Those are usually just calcium chloride in a bag, it's very hygroscopic and fairly cheap... also makes a halfway decent de-icer. The issue I see with this thin-film method is that no mention is made of the rate of production at a given relative humidity for a given area of the film. It's interesting, but without the details (and with a lot of PR speak) I'm skeptical as hell about this in practice.
- the__alchemist 1y ago
  Dehudifier bags (e.g. silica, CaCl) aren't single-use. Microwave, then reuse. Some even are color-changing so you know how much moisture they've absorbed.
  - dotancohen 1y ago
    Microwaving is adding energy, obviously. But the idea here is that the water is recoverable, not that the air is now drier.
    - the__alchemist 1y ago
      Concur; the idea behind this class of devices is to take advantage of a daily humidity cycle. Whether it's CaCl (absorption) or Silica (adsorption), or the latest lab-designed adsorption surface. This is a good time to note that I see one of these articles ~once every two years, for the past 10 years. I haven't observed one make it beyond the initial discovery phase.
WalterBright 1y ago
Thanks for the explanation. My first thought reading the headlines was somebody thinks they discovered a perpetual motion machine.
- galangalalgol 1y ago
  What is the theoretical limit on the energy cost to remove water from air? A dew years back 3m had some super inexpensive way that invovled a reusable water andorber that released its water under only slightly decreased pressure and slightly increased temperature. The incoming air and the waste heat from the downstream ac unit provided all the warming with the pressure change being all that was necessary. It had two banks so one could dump water while the other absorbed. It made the whole system rund double digiymore efficient than just the ac alone. And that was neglecting that the felt temperature would be lower with the dessicated air.
  - chrisweekly 1y ago
    > "remove water from air? A dew years back" "dew" was a funny typo there :)
    - felbane 1y ago
      The loss of tactile keyboards on mobile devices is a tragedy.
deadbabe 1y ago
Yes it is impossible to break the laws of physics. If they appear broken then it is only because our understanding was wrong. Similar, the laws cannot be “defied”. You can only do what the universe allows, nothing more.
aaron695 1y ago
[dead]
rtpg 1y ago
Is there some sort of conservation of energy question in this form of water collection that establishes some minimum amount of energy that would be required to collect 1L of water from the air? I'd assume if the amount of energy required to collect the water is low then we're looking at something interesting.
- tsimionescu 1y ago
  Yes, water vapor condensing to liquid water at humidity below 100% is an exothermic reaction, and the amount of energy released is (per Google) 2259kJ/kg. So any device that wants to condense 1kg of water has to dissipate at least 2259kJ of energy somewhere, assuming it is in any way temperature-dependent (if it can keep condensing water even if it becomes hotter, then this is somewhat evaded). For context, that amount of heat is five times the amount needed to heat 1kg of liquid water from 0° to 100°C (without thawing or boiling it). So it's not in any way a trivial amount.
dumbfounder 1y ago
So the question is how much more efficient is it? I spend hundreds of dollars per month running dehumidifiers in my house so I am keen to know.
- strontian 1y ago
  Me too! Because dust mites? Curious to share notes with you, I’m running 4 aeockys right now but they don’t seem to last long
gsf_emergency 1y ago
The red flags in the uni PR are not so curious compared to the ones in the paper. From figure 4 (& backed up by simulation fig 3E) it looks like stuff begins to happen only at 97% relative humidity & after a few minutes (at micrometer scale) https://www.science.org/doi/10.1126/sciadv.adu8349 https://www.science.org/doi/10.1126/sciadv.adu8349 Granted, it's almost easy enough to try at home: melt some poly gloves into "freeze dried" silica powder
TimByte 1y ago
Yeah, "harvesting" probably oversells it unless there's a passive or low-energy way to actually collect the water. Like, maybe coupling it with a wicking surface or capillary-driven transfer system could help, but that’s an open question.

Evidlo 1y ago

When a publication I was involved in got a university PR piece, they were in direct communication with us

Y_Y 1y ago
Amusingly, I have the same experience as you and GP. Thee university wants to hear what the researchers have to say, but subsequently they decide independently what they're writing, strict scientific honesty be damned.
- B1FF_PSUVM 1y ago
  Honesty pays no bills for professional liars. Like diplomats, they're sent abroad to lie for their university, and the university president cries all the way to the bank for the sins of his hirelings.
beloch 1y ago
University PR folk are sometimes quite scientifically illiterate. Their job is basically marketing. They need to turn an esoteric, jargon heavy, and heavily qualified paper into a hype piece that the money people can understand. Everything must be a ground-breaking, world-shaking, all-time first. They sometimes make dubious claims no matter how many times you tell them not to. Ultimately, they report to the university's money people and not to researchers. If you want science, read journals. If you want to see who is likely to get more money, read university PR releases.
wenc 1y ago
I've observed the same. University science PR pieces are usually unreliable -- they are optimized toward generating buzz than scientific accuracy. They usually link to the actual science papers, but the prose is usually a stretch. Even in this case -- "defying the laws of physics" is sensationalist narrative manufacturing. The real claim is actually more moderate, and the research is not really close to commercial yet.

wenc 1y ago

It's research-in-progress, but I think the promise is slightly different from dehumidifier bags (also in other parts of the world, Thirsty Hippos [1]) which are single use. You're correct in that: (1) it doesn't break the law of physics; (2) to remove the droplets, you still need energy. But it sounds like if the droplets are moving to the surface, the energy needed to release the droplets could be far lower than most active dehumidification methods (e.g. Peltier junctions). [1] Thirsty Hippos -- which are very effective in small spaces. https://www.amazon.sg/Thirsty-Hippo-Dehumidifier-Moisture-Absorber/dp/B0713TGZD6 https://www.amazon.sg/Thirsty-Hippo-Dehumidifier-Moisture-Ab... Basically a supercharged silica gel.

EA-3167 1y ago
Those are usually just calcium chloride in a bag, it's very hygroscopic and fairly cheap... also makes a halfway decent de-icer. The issue I see with this thin-film method is that no mention is made of the rate of production at a given relative humidity for a given area of the film. It's interesting, but without the details (and with a lot of PR speak) I'm skeptical as hell about this in practice.
the__alchemist 1y ago
Dehudifier bags (e.g. silica, CaCl) aren't single-use. Microwave, then reuse. Some even are color-changing so you know how much moisture they've absorbed.
- dotancohen 1y ago
  Microwaving is adding energy, obviously. But the idea here is that the water is recoverable, not that the air is now drier.
  - the__alchemist 1y ago
    Concur; the idea behind this class of devices is to take advantage of a daily humidity cycle. Whether it's CaCl (absorption) or Silica (adsorption), or the latest lab-designed adsorption surface. This is a good time to note that I see one of these articles ~once every two years, for the past 10 years. I haven't observed one make it beyond the initial discovery phase.

WalterBright 1y ago

Thanks for the explanation. My first thought reading the headlines was somebody thinks they discovered a perpetual motion machine.

galangalalgol 1y ago
What is the theoretical limit on the energy cost to remove water from air? A dew years back 3m had some super inexpensive way that invovled a reusable water andorber that released its water under only slightly decreased pressure and slightly increased temperature. The incoming air and the waste heat from the downstream ac unit provided all the warming with the pressure change being all that was necessary. It had two banks so one could dump water while the other absorbed. It made the whole system rund double digiymore efficient than just the ac alone. And that was neglecting that the felt temperature would be lower with the dessicated air.
- chrisweekly 1y ago
  > "remove water from air? A dew years back" "dew" was a funny typo there :)
  - felbane 1y ago
    The loss of tactile keyboards on mobile devices is a tragedy.

deadbabe 1y ago

Yes it is impossible to break the laws of physics. If they appear broken then it is only because our understanding was wrong. Similar, the laws cannot be “defied”. You can only do what the universe allows, nothing more.

aaron695 1y ago

[dead]

rtpg 1y ago

Is there some sort of conservation of energy question in this form of water collection that establishes some minimum amount of energy that would be required to collect 1L of water from the air? I'd assume if the amount of energy required to collect the water is low then we're looking at something interesting.

tsimionescu 1y ago
Yes, water vapor condensing to liquid water at humidity below 100% is an exothermic reaction, and the amount of energy released is (per Google) 2259kJ/kg. So any device that wants to condense 1kg of water has to dissipate at least 2259kJ of energy somewhere, assuming it is in any way temperature-dependent (if it can keep condensing water even if it becomes hotter, then this is somewhat evaded). For context, that amount of heat is five times the amount needed to heat 1kg of liquid water from 0° to 100°C (without thawing or boiling it). So it's not in any way a trivial amount.

dumbfounder 1y ago

So the question is how much more efficient is it? I spend hundreds of dollars per month running dehumidifiers in my house so I am keen to know.

strontian 1y ago
Me too! Because dust mites? Curious to share notes with you, I’m running 4 aeockys right now but they don’t seem to last long

gsf_emergency 1y ago

The red flags in the uni PR are not so curious compared to the ones in the paper. From figure 4 (& backed up by simulation fig 3E) it looks like stuff begins to happen only at 97% relative humidity & after a few minutes (at micrometer scale) https://www.science.org/doi/10.1126/sciadv.adu8349 https://www.science.org/doi/10.1126/sciadv.adu8349 Granted, it's almost easy enough to try at home: melt some poly gloves into "freeze dried" silica powder

TimByte 1y ago

Yeah, "harvesting" probably oversells it unless there's a passive or low-energy way to actually collect the water. Like, maybe coupling it with a wicking surface or capillary-driven transfer system could help, but that’s an open question.