195
Penn Engineers Discover a New Class of Materials That Passively Harvest Water from Air
(blog.seas.upenn.edu)
this post was submitted on 26 May 2025
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Technology
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If this is legit, it's going to be revolutionary.
If a "passive dehumidifier" is possible using this and a funnel/hose, that could be extremely exciting for basement and cellar owners everywhere
depends how space efficient it is. maybe you would you need to fill your entire basement with the stuff for it to work.
A surface-area maximizing structure like a radiator grille could probably be used if it's anywhere near reasonable, but yeah, that could be a concern
That seems like it would violate the law of entropy by turning a high entropy state (water vapor mixed into the air) into a lower entropy state (water in liquid form), but I'm probably just missing something.
I don't at all understand why the second law of thermodynamics is being invoked. Nonetheless, capillary condensation is already a well-studied phenomenon. As the scientific article itself notes, the innovation here over traditional capillary condensation would be the ability to easily remove the water once it's condensed.
Re: Entropy:
The entropy of a little water mixed with air is higher. As with anything that mixes a little.
Condensation is exothermic, though, so the material will heat up slightly
Yeah that was my thought too. I hope it makes it to actual use cases and not just lab proof of concept.
Yeah now we can industrially extract all the remaining water from the air as well as the ground.
edit: Sorry I thought it was obvious this was slightly tongue-in-cheek.
You realize the amount of water is constant, right?
Not if Nestle has anything to say about it
They do have a point about groundwater though.
We prefer the term “recycled dinosaur pee”.
FMT99 missed the week they taught the water cycle.
Water is created and destroyed by biological and other natural processes. Here go photosynthesis:
6CO₂ + 6H₂O + Light → C₆H₁₂O₆ + 6O₂
I am fairly certain they are referring to the fact that we are already removing water from the fresh water cycle, and this could remove even more. For example, global warming combined with draining the aquafers means less water in the cycle as it was drained into the ocean and isn't beaing replenished as snow/glaicers.
Yes, the total volume of water on the planet isn't being changed by that shift, but the amount of freshwater is.
Nobody will remove water from ambient air in relevant amounts. Roughly 0.5 % of air is water vapor, a total of something like 10'000 km³ liquid water. This is replaced (residence time) about once every 10 days, so roughly 1'000 km³ daily.
Say we extract 10 km³ (10'000'000 m³) daily, enough for roughly 10 million people (including all industry, zero recycling of the water etc.). By that time you deal with 1 % of earths atmosphere every day. May I remind everyone how absurdly costly in any conceivable way that would be? You would rather lay a few pipes and purify sea water at a tiny(!) fraction of the cost.
They won't drain the aquifers, nature will replace that much water!
They won't cut down all the forests, the trees will just regrow!
They don't have to cycle the entire atmosphere to cause havoc. Pulling the moisture out in local areas that already have lost aquifers and ice in the mountains is the obvious issue. Plus, you don't know the cost in the long run, it could end up being fairly cheap.
People were able to (and at some places did) cut down every tree WELL before they had power tools and even saws. Just with axes. The comparison is laughable.
No, massive air moving structures can not be cheap. Neither building nor operating them.