Practical Water from Desert Air ?

Thought this would be of interest ? H2O from Desert air ?

By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.

With a little jiggery pokery.. This could solve a few problems if commercial and it certainly sounds that way.

Abstract Energy-efficient production of water from desert air has not been developed. A proof-of-concept device for harvesting water at low relative humidity was reported; however, it used external cooling and was not desert-tested. We report a laboratory-to-desert experiment where a prototype using up to 1.2 kg of metal-organic framework (MOF)–801 was tested in the laboratory and later in the desert of Arizona, USA. It produced 100 g of water per kilogram of MOF-801 per day-and-night cycle, using only natural cooling and ambient sunlight as a source of energy. We also report an aluminum-based MOF-303, which delivers more than twice the amount of water. The desert experiment uncovered key parameters pertaining to the energy, material, and air requirements for efficient production of water from desert air, even at a subzero dew point.

INTRODUCTION About 13 sextillion (1021) liters of water exist in the atmosphere at any given time (1). This is a recyclable natural resource with potential to water the arid regions of the world. Methods to harvest water from humid air are known (2–6), but doing so at low humidity in desert climates is as yet undeveloped (7). The difficulty in establishing a practical water harvesting cycle (WHC; Fig. 1) for low-humidity climates is twofold: finding a material capable of facile water capture and release (capture cycle) and providing sufficient cooling energy such that the temperature of the condenser is lower than that of the released water vapor to allow for liquid water formation (collecting cycle). Although the two cycles have been shown to work with intensive energy input (8), it remains unknown whether they can produce water under natural cooling with energy only from ambient sunlight.

advances.sciencemag.org...

a reply to: skywatcher44

I can see climate crazies getting behind this without thinking it through.

One of the climate crazy's "main claims to fame" is that, no, the climate's getting worse here and better over there, it's getting hotter here and colder over there, it's getting dryer here and wetter over there.

Extracting the water from the air will therefore decrease the amount of average water in the air, in effect lowering the average RH according to AGCC theology. It would also potentially reduce the way water in the air reflects sunlight, potentially increasing the global mean temperature.

It is possible that ocean evaporation could fill the RH void, but there would likely be a lag in the feedback system, plus it's adding another artificial variable to an already complex natural system. So there is a reasonable probability that using water traps in the deserts initially, will reduce the entire planet to a desert eventually.

This idea is about as good as beaming microwave from orbiting satellites to ground stations, although the effect would be worse as you don't pump a closed system full of any kind of energy. Just my opinion....

Cheers - Dave

a reply to: skywatcher44

Great , now we want to steal water from desert plants and animals !

Although the two cycles have been shown to work with intensive energy input (8), it remains unknown whether they can produce water under natural cooling with energy only from ambient sunlight.

Cost over benefit analysis could prove to be it's downfall in the short term but at some point it could be viable , until then they could always try the old method of dig a hole , line it with plastic and put a stone at the bottom.

They have a system now that can collect water from fog on mountains in dry areas that get fog because they are next to the ocean, etc. Pulling it out of dry air is no doubt much harder, and why do we want to put even more people in the desert anyway?

Maybe we can install the techniques of the moisture farmers from the desert planet Tatooine. Luke Skywalker seemed to have it figured out.

Two vids come to mind







But your airco does it all the time.

So hook up a solar panel to your airco and have water and coldness

Theres this as well.
Zero Mass Water

Isn't how Episode IV of 'Star Wars' started?
Luke's family were something like 'water farmers' with little droids roaming the dunes gathering moisture.

If you can map the temperature differentials at depth then why not run piping underground which will be cooler as per this gradient and then set up an autonomous air flow system which sucks hot surface air down and through the pipes and in the process cools and condensates within the pipe.....giving you water....no moving parts....no maintenance...constant operation.

Why make it rain less by removing water vapor?

Desalination seems like the only reasonable path forward.

... was tested in the laboratory and later in the desert of Arizona, USA.

Yeah, but it's a dry heat. It can get to 110° with the relative humidity in the single digits. I know because I live here.

You'd get more blood from a turnip than water from the Arizona air.

originally posted by: Shadoefax

... was tested in the laboratory and later in the desert of Arizona, USA.

Yeah, but it's a dry heat. It can get to 110° with the relative humidity in the single digits. I know because I live here.

You'd get more blood from a turnip than water from the Arizona air.

Except for maybe 2 weeks in August, of course.

originally posted by: bobs_uruncle
a reply to: skywatcher44

I can see climate crazies getting behind this without thinking it through.

One of the climate crazy's "main claims to fame" is that, no, the climate's getting worse here and better over there, it's getting hotter here and colder over there, it's getting dryer here and wetter over there.

Extracting the water from the air will therefore decrease the amount of average water in the air, in effect lowering the average RH according to AGCC theology. It would also potentially reduce the way water in the air reflects sunlight, potentially increasing the global mean temperature.

It is possible that ocean evaporation could fill the RH void, but there would likely be a lag in the feedback system, plus it's adding another artificial variable to an already complex natural system. So there is a reasonable probability that using water traps in the deserts initially, will reduce the entire planet to a desert eventually.

This idea is about as good as beaming microwave from orbiting satellites to ground stations, although the effect would be worse as you don't pump a closed system full of any kind of energy. Just my opinion....

Cheers - Dave

I agree, this sort of technology is better off for terraforming outposts.

What would happen if you pulled air from directly above the ocean or maybe a 100-1,000ft out (maybe like a tunnel). If it was a sea breeze (coming off the ocean, not from land) then the air would probably be more humid. If it was pulled through a long tunnel it might pick up more water over the length in comparison to pulling air in on the beach. You would need a fairly large diameter tunnel if it is long due to the resistance/friction of the air moving. I guess temp would also play a big role in this with higher temps being able to support more moisture content. IDK if something like this could be used for large scale as it seems the efficiency would increase exponentially, relative to cost, the larger you get when it comes to building the tunnel and the cooling/condensation could most likely be done with ocean water and maybe a little external cooling once the air has dropped to the temp of the ocean water (so first chiller is ocean water temp, second one that extracts most water is actively chilled). You would also have a lot of chilled air to work with if that was of use..

I wonder how much water is lost to evaporation from the condensate on air conditioners in desert cities? That would be something interesting to study, the amount of water produced from AC's. It all comes from the air and it eventually returns but it could be used to water plants or something. That is often why grass/weeds grow better under window air conditioners in dry areas.

originally posted by: DigginFoTroof
What would happen if you pulled air from directly above the ocean or maybe a 100-1,000ft out (maybe like a tunnel). If it was a sea breeze (coming off the ocean, not from land) then the air would probably be more humid. If it was pulled through a long tunnel it might pick up more water over the length in comparison to pulling air in on the beach. You would need a fairly large diameter tunnel if it is long due to the resistance/friction of the air moving. I guess temp would also play a big role in this with higher temps being able to support more moisture content. IDK if something like this could be used for large scale as it seems the efficiency would increase exponentially, relative to cost, the larger you get when it comes to building the tunnel and the cooling/condensation could most likely be done with ocean water and maybe a little external cooling once the air has dropped to the temp of the ocean water (so first chiller is ocean water temp, second one that extracts most water is actively chilled). You would also have a lot of chilled air to work with if that was of use..

Maybe a fog catcher? or another fog catcher.

These folks seem to be rather advanced with the systems: FogQuest

Notice that Fog Catchers NEED FOG - not dry desert air.