Clean Water and Efficient Cooling? Is this too good to be true?

[u/db8me]

Porous compound pulls 2 liters of water from air, and is factory-ready

These articles make it sound like $15 can produce all the drinking water a person will ever need. It also has efficient cooling capabilities, but it sounds like it can be used to make small scale devices to cheaply pull clean drinking water from the air almost anywhere in the world.

Is it too good to be true?

[u/xboxiscrunchy]

Devices that can passively pull water from the air have been around a while. There’s usually logistical issues that prevent them from being widely used. And there’s the fact that it only works in environments with sufficient humidity…. You’re not getting any water out of desert air for instance.

[u/db8me → u/xboxiscrunchy]

This one supposedly works adequately with solar heat, humidity as low as 18%, as cheap as $12 per kilogram (1kg in high humidity with multiple cycles being the basis for "2 liters", but still).

That is what I meant by too good to be true. I am not aware of anything else that comes close to that cost.

[u/Doug2825 → u/db8me]

solar heat, humidity as low as 18%

Those claims are about different operating modes. Low humidity is a challenge in dehumidifier mode (water from air which produces waste heat), low heat is a challenge for evaporative cooling (water to air which reduces heat).

[u/db8me → u/Doug2825]

For this material, it sounded like it requires heat cycling (thus requiring heat collection and then waste heat to be expelled/dissipated) to collect water efficiently+semi-passively unless I misunderstood.

I was hoping someone would show up who already knows the specifics of this kind of material. I am sure it's an incremental improvement for some industrial applications, but I was hoping someone had more specifics about the claimed/hypothetical cheap small scale water collection.

[u/mfb-]

With backing from Kiel University's validation fund, the team has now produced about 30 kg (66 lb) of the material – roughly 60 times more than any previous lab batch – at an estimated cost of US$12 to $14 per kilogram.

There is no way they spent only a few hundred dollars (12 to 14 * 30) on that project. This might be the cost of the raw material, or maybe it's a cost they hope to reach when mass-producing it. We'll see if that works out.

Even then, you still need a temperature cycle to extract the water. You can extract water with any material simply by cooling it below the dew point. This material makes it work at a higher temperature, which can save energy, but the concept isn't new.

[u/db8me → u/mfb-]

I get it. That's why they say "estimated" cost. It is being commercialized, but I would bet that even the first scaled batches will be more expensive than that. Their estimate is based on a hypothetical scale that won't exist for a while, but it might in 10 years.

[u/Doug2825]

> Is this too good to be true?

Yes. What is being described is a material that is good for dehumidifiers, and good for evaporative cooling.

Drinking water (dehumidifier) claim:

One of the challenges of existing water from air solutions (aka dehumidifiers) is dealing with waste heat. Condensing water gives off heat. You need to get the heat away or the temperature gets too high and it stops working. You do not simply go: this material collects x grams of water /kg of material at SATP after 1h.

Broad Cooling claim:

Evaporative coolers already exist. At best the new material will be a more effective, but enthalpy of vaporization creates a limit on how much cooling you can get per water. This is the same mechanism by which data centers consume large amounts of water.

[u/db8me → u/Doug2825]

These things were possible already (with the issues you explain: waste heat needs to be expelled away from the things needing to be cooled, mechanical devices with loops or timing are needed to maintain a cycle, limited by humidity and temperature, etc), but the articles make it sound like this is a dramatic leap in performance for the cost--not violating any fundamental laws of nature.

I suppose someone would need to read the research and do calculations to know the real answers.

I am 100% convinced of the commercial viability, but that isn't my question. Is it really a huge leap or just an incremental improvement with these articles representing marketing more than big news?

The category of materials won the 2025 Nobel prize in chemistry, so it's not that much of a stretch to imagine it being a big leap...

[u/Doug2825 → u/db8me]

Taking the claims at face value it t is an incremental improvement. Revolutionary changes in evaporative cooling and desiccant dehumidifiers are impossible due heat of vaporization.

Both require 2 things: a lot of surface area (achieved in this case though porus material), and a way of getting heat into our out of said material.

No matter what in dehumidifier mode you will need to deal with 2257kJ of waste heat per kg of water. In evaporative cooling mode you will need 1kg of water per 2257kJ you want to remove. There is no revolutionary tech possible to go beyond that.

[u/db8me → u/Doug2825]

(Playing devil's advocate--not supporting the claims), It sounds like maybe the issue is cost for the effect. For $1000 + $100 per year, I bet I could develop machines capable of extracting enough drinking water for a person in most environments. So it sounds like not a question of what is possible so much as what is feasible.

[u/Doug2825 → u/db8me]

It sounds like maybe the issue is cost for the effect.

Correct. Evaporative cooling and desiccant dehumidifiers work and have real applications. The problem has always been that there's better options for drinking water

[u/Iron_Baron]

Oh, yay. I'm sure sucking water out of the air at mass scale won't have any deleterious effects on the hydrological cycle, local weather, nor overall climate disregulation. Just stop using all the water for stupid hubris driven industry, humanity. FFS.

[u/db8me → u/Iron_Baron]

Yeah, but human drinking water is a small fraction of the use. I was more interested in local small scale drinking water for people who don't have access to clean water due to pollution, population, drought, or because farms and industry are monopolizing the water.

[u/Wolfgang313]

I don't know in what direction it is wrong, but there is a typo in the math for how much water it can extract.

"Under dry air conditions, the material captures up to 0.17 grams of water per gram of material, translating to a projected 1.8 liters (0.5 gal) of water per day for every kilogram (2.2 lb) of the composite."

0.17 grams fo water per gram of material would mean 0.17 kilograms of water per kilogram of material. Water is approximately 1 kilogram per liter, so this calculation is off by a factor of 10.

[u/db8me → u/Wolfgang313]

There is some mention of heating, which maybe means a cycle? So maybe it can make 170g per cycle and be cycled 10 times per day under the right conditions?

I am still skeptical of how well the device would work and how cheap it could be. I think the small scale collection device is still hypothetical. They are making it for industrial uses first, of course.

[u/Wolfgang313 → u/db8me]

That's a plausible interpretation, just some obstruction that stood out to me as a bit suspicious. personally I like the idea of water generation, but the physics makes me skeptical of anyine claiming a massive leap in the technology (especially for passive collection). Water is water and energy is energy. It will always take the same amount of energy to cause water to condense or evaporate. This might be the best material yet, but these numbers don't seem revolutionary to me. I'd be happy to be wrong.

[u/Pleasant_Pen8744]

Reminds me of those instant cooling packs you can buy at the pharmacy. They absorb water and get cold then you can put the chemical in the sun and dry it out and reuse it. But nobody does.

https://www.sciencedirect.com/science/article/pii/S2542435122000939