Ok, I have a dumb question about this sort of technology. Aren't these devices essentially just borrowing from tomorrow by capturing moisture that would have eventually collected as clouds? Are there any long-term ramifications to using these?
Clouds are quite cheap. Most of them drop most of their water over areas that would not significantly suffer from a marginal reduction of rainfall (the oceans, the arctics, mountain ranges).
And a dryer average atmosphere should be partially compensated by increased evaporation from the oceans. Overall, this technology should be applicable on a continental scale before it shows any measurable effect on other areas.
A far more accurate response is “we have no idea and no way of knowing there wouldn’t be major negative ramifications but it would seem like...”
My biggest gripe with climate science in popular media is the presentation of sparse data and unproven models as fact that should be take at face value. Milking clouds in one region will have an impact elsewhere, that’s the only guarantee.
> areas that would not significantly suffer from a marginal reduction of rainfall (the oceans, the arctics, mountain ranges)
Agreed as to the ocean and the arctic, but precipitation over mountain ranges is generally recovered by lower-altitude communities when the water eventually flows down to them.
Snowmelt has been a major source of water historically.
In some sort of absolute sense, sure, water in the device is not water somewhere else. But with something like 326,000,000,000,000,000,000 gallons of water on Earth, it's well below the noise threshold. Even "dry desert air", if you work it out, has massive (heh, literally) amounts of water in it.
Plus the impact is even less than you think, because air that has been made dry is more able to pick up water, so you have to work even harder than you'd think to have any impact.
I used a moisture calculator to determine that 10% humidity desert air at 30 degrees celsius and 1013.25hPa air pressure contains 3.03g/m³ of water. At that rate, the air above a 100x100m football field (to altitude of 100m) contains 303kg of water, or 303L at 4 degrees celsius.
So you'd be "drying out" a very tiny cube of air to produce the water needed by an entire family per day even given desert conditions with one of these appliances.
In the first world, we use 100L/day for all our needs. That means if everyone in America lived in a desert, we might need 107,491,749,174,917.5 cubic meters of air to supply us with all our water. If that sounds like a lot of air, consider that Death Valley is 7.8e+9 square meters in area; thus, to supply ALL Americans with fresh water, you'd just need to suck Death Valley's air dry to an altitude of 10,000m or so.
Maybe, but the scale here is gigantic, and it will take a lot of work for humans to make an impact. Consider that a single cumulus cloud can weigh 2 million pounds(that is, 900 cubic meters of liquid water).
If you were going to be worried about things like this, wind farms will probably pose a bigger problem than water collection, unless we start building large cities in the desert relying only on air moisture collection.
Long term ramifications I'm sure of. Long term harmful ramifications? I doubt it. That water has to go somewhere, whether it's captured in the ground or evaporates in the skies, the machinery of nature will keep ticking :)
- Dust would need to be swept off to allow sunlight energy to reach the solar chamber.
- Ambient temperature on mars in below the freezing point of water. May not get enough sun to warm the MOF enough to drive off the moisture. EDIT: Found a source saying that water vaporizes during the day because of the reduced pressure - interesting.
This is pretty neat. From previous papers it is using temperature swing adsorption[1] pull the water out of the air. Basically their MOF material collects on its surface (adsorbtion) water at one temperature and releases it (desorption) at the other. In this way, just by putting their material out in the Sun light the day/night cycle will collect and then dispense the collected water all passively.
The 'catch' is how expensive is it to produce the MOF and how long does it work before it needs to be replaced. In an ideal world, with a cheap catalyst and infinite lifetime, you could build a large tower full of this stuff and it would pour water out during the desorption process.
Yes, you can extract water from air. You have just re-invented distillation, in a painfully mind blowing way.
In Chile we have the driest desert on earth, the Atacama desert, this projects have “tried” to address the challenge of getting fresh water in remote communities located in such places. State funds have been directed toward similar "science" projects. TV has dedicated time and resources to explore this "idea".
This has to stop, the amount of water that you can extract from air is related to the amount of humidity in that place's air. You don't need much to understand that the amount of water in the air isn't much in places such as deserts. And if you have lots of humidity in the air, you can probably get water from other sources, such as rain.
Air already has X amount of water, you cannot get more than X. It doesn't matter if X is very tiny like in deserts or very large like in the middle of the pacific ocean.
You are absolutely right. No matter how many down-votes you receive. The scientific illiteracy on HN is astounding considering the audience it tries to cater to (college-educated software engineers).
It really is astounding. About the wettest the atmosphere can get is a rain cloud and one several kilometres in height and several kilometres in length will drop a few millimetres of water. Yet people seriously believe that these little things will suck more water out of much less atmosphere.
could this idea work? tie these devices to balloons, so they can reach the high humidities of the clouds, then when waters collect the balloons will drop to the ground, dumping the water into a collector. as the water is dumped the device rises again to continue humidity collection.
You're taking something simple and making it very complicated.
The reason clouds form is not because there's more water up there, but because temperatures and pressures are lower and the air can't hold on to the water anymore, and the water separates into droplets of liquid water or ice.
There's plenty of water at ground level, even in lip-cracking low humidity, as long as it's not also freezing.
The trick is getting what water there is to leave the air and to collect in your bucket, and collecting a meaningful amount.
Seems interesting, for small, possibly off the grid, desert communities. Not sure how the overall lifecycle energy demands would compare to say desalination for most of the coastal population centers.
Readit News
And a dryer average atmosphere should be partially compensated by increased evaporation from the oceans. Overall, this technology should be applicable on a continental scale before it shows any measurable effect on other areas.
My biggest gripe with climate science in popular media is the presentation of sparse data and unproven models as fact that should be take at face value. Milking clouds in one region will have an impact elsewhere, that’s the only guarantee.
Agreed as to the ocean and the arctic, but precipitation over mountain ranges is generally recovered by lower-altitude communities when the water eventually flows down to them.
Snowmelt has been a major source of water historically.
Plus the impact is even less than you think, because air that has been made dry is more able to pick up water, so you have to work even harder than you'd think to have any impact.
So you'd be "drying out" a very tiny cube of air to produce the water needed by an entire family per day even given desert conditions with one of these appliances.
In the first world, we use 100L/day for all our needs. That means if everyone in America lived in a desert, we might need 107,491,749,174,917.5 cubic meters of air to supply us with all our water. If that sounds like a lot of air, consider that Death Valley is 7.8e+9 square meters in area; thus, to supply ALL Americans with fresh water, you'd just need to suck Death Valley's air dry to an altitude of 10,000m or so.
Deleted Comment
Deleted Comment
Not that it's necessarily bad, but widespread usage would have to have _some_ environmental impact.
If you were going to be worried about things like this, wind farms will probably pose a bigger problem than water collection, unless we start building large cities in the desert relying only on air moisture collection.
In what way would this particular device not work as advertised?
The humidity at the surface is 30 to 75 ppm [1]. Clouds have been known to form.
If Elon Musk gets interested, I think the MIT researchers could get the investment they need to scale this up.
I'm just grateful to read some good news about scientific progress for a change. Useful inventions like this give me more hope for humanity.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4508910/
Few potential issues come to mind:
- I bet dust would muck up the MOF
- Dust would need to be swept off to allow sunlight energy to reach the solar chamber.
- Ambient temperature on mars in below the freezing point of water. May not get enough sun to warm the MOF enough to drive off the moisture. EDIT: Found a source saying that water vaporizes during the day because of the reduced pressure - interesting.
The 'catch' is how expensive is it to produce the MOF and how long does it work before it needs to be replaced. In an ideal world, with a cheap catalyst and infinite lifetime, you could build a large tower full of this stuff and it would pour water out during the desorption process.
[1] https://www.ethz.ch/content/dam/ethz/special-interest/mavt/p...
In Chile we have the driest desert on earth, the Atacama desert, this projects have “tried” to address the challenge of getting fresh water in remote communities located in such places. State funds have been directed toward similar "science" projects. TV has dedicated time and resources to explore this "idea".
This has to stop, the amount of water that you can extract from air is related to the amount of humidity in that place's air. You don't need much to understand that the amount of water in the air isn't much in places such as deserts. And if you have lots of humidity in the air, you can probably get water from other sources, such as rain.
Develop the tech in easier locales then, once the major details are worked out, target the outliers.
The reason clouds form is not because there's more water up there, but because temperatures and pressures are lower and the air can't hold on to the water anymore, and the water separates into droplets of liquid water or ice.
There's plenty of water at ground level, even in lip-cracking low humidity, as long as it's not also freezing.
The trick is getting what water there is to leave the air and to collect in your bucket, and collecting a meaningful amount.
Deleted Comment
Deleted Comment
The water extracted was probably going to fall somewhere else, but now it won't.
https://www.zeromasswater.com/
Is it the minimum humidity rating?
Here is it after a quick search, open access too:
https://www.nature.com/articles/s41467-018-03162-7
Seems interesting, for small, possibly off the grid, desert communities. Not sure how the overall lifecycle energy demands would compare to say desalination for most of the coastal population centers.