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Comment on Device that can extract 1,000 liters of clean water a day from desert air revealed by 2025 Nobel Prize winner

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Hi_ImSomeone@lemmy.world ⁨2⁩ ⁨days⁩ ago

Technically yes! To put it in perspective, there’s about 2.5kg of water in the atmosphere per m^2 of earth surface area. If you put enough panels across the earth, you could probably do a decent job at taking some of the water out of the air.

We have to look at another factor affecting the water in the air. As we take water out of the air, it’s not really a finite resource. Most water in the air generally comes from the sun evaporating the oceans. If we take the water out of the air, the sun will put the water back. There’s always a balance of humidity and quantity evaporated. When the humidity is lower, the sun would have an easier time evaporating more water due to the osmosis of the water from the source (ocean) going into the air. Osmosis is a kind of log graph, so even if the humidity is lower, the exponential tail means the solar evaporation and humidity pretty much balances out at the end of the day.

It’s similar thing to taking water from a river. If we take all the water from a river, can we dry up downstream? Yes! But considering the height of the atmosphere, it’s like standing at the edge of the river trying with a bucket and trying to scoop everything up. Unless these water-from-air harvesters can reach all the way to the clouds, we probably won’t dry anything up.

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ammonium@lemmy.world ⁨2⁩ ⁨days⁩ ago
Not that I think your device has the same danger because water captured from the air will likely quickly be released again into the same air, but I think this is not a very good example of the safety of your device:

It’s similar thing to taking water from a river. If we take all the water from a river, can we dry up downstream? Yes!

We can and we do. The Colorado and the Yellow river no longer consistently reach the ocean.

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- Hi_ImSomeone@lemmy.world ⁨1⁩ ⁨day⁩ ago
  The comparison I was trying to make is that we do have the power to capture 100% of a river. This isn’t good, for obvious reasons. Humidity capture is a much different process, since we can’t just capture 100% of the humidity from a panel either. You could have 80% humidity going in, but actually still 50% relative humidity going out. And that would be maximum absorbtion performance!
  
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FlyingCircus@lemmy.world ⁨2⁩ ⁨days⁩ ago
Thanks for your answer! I feel like that makes sense on a global scale, but mightn’t local and regional scales be more impacted? We already know that the transpiration from forests affects rain patterns, and the forests don’t need to be huge either.

Also, some ecosystems might be particularly vulnerable. For example, redwood trees actually absorb most of their water through their leaves from fog and mist. Could a local humidity harvesting plant potentially pull enough water from the air that the osmotic pressure is reduced below what redwoods need to absorb water? I suspect the answer is actually no for this particular examole, but my point is that powerful technologies like these must be thought through, especially if someone is claiming zero side effects. The time is long past for humanity to learn a little caution with potential climate changing technologies.

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- Hi_ImSomeone@lemmy.world ⁨1⁩ ⁨day⁩ ago
  As for local or regional scales, yes there could be impacts. I’m not quite as well versed in how trees affect the environments, but I suspect a local water-from-air farm would have some impacts on a local scale. If we had some data on how redwood trees absorb based on the different environmental conditions, I could run some numbers to figure out the differences and see how it would be affected.
  
  Agreed on the impacts though, this isn’t a zero impact technology, but compared to the direct competitors it is trying to replace (groundwater harvesting or desalination), it is an improvement. A mindset I like to apply is that humanity will need water regardless of how they get it. New technologies should provide a solution that is lower impact, along with a financial incentive (cost).
  
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