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  Reply # 1642790 29-Sep-2016 17:03
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PhantomNVD: Now that is really overboard!

Firstly condensate is by definition pure water, and secondly, 60L/day will do NOTHING to the general level of the air content, even if every person in the whole country did this...

Directly from the FAQ of the original link:

What is air-to-water technology?
Air-to-water technology is the process of converting water vapor in the air (humidity) to water. replicates this natural process of condensation by simulating the dew point, which allows it to make water continuously, even in low humidity conditions.

How much water is in the atmosphere? Is air vapor an unlimited resource?
There’s approximately 3100 cubic miles (mi3) or 12,900 cubic kilometers (km3) of water in the atmosphere. That’s almost enough water to fill all the Great Lakes of the United States. Water vapor is an unlimited resource constantly replenished by nature’s hydrologic cycle so extracting water from air can continue indefinitely without impacting the planet.


In NZ, we are surrounded by ocean, even if we were able to effect a change to the average humidity of the country, the ocean would be replenishing it on a continual basis, turning salt water into clean is exactly what the water cycle does, and the reason life on earth is possible.

 

Using the sales brochure for evidence is just naive. In some countries, the evaporation rate far exceeds the precipitation rate. In those countries, you would be pushing it uphill to condense water from the air. And this kind of argument used to justify taking water out of rivers and aquifers. And to pumping CO2, and methane, and CFCs, into the atmosphere. Nothing comes for free, and nothing is unlimited.

 

I'm happy to admit that I didn't do any sums to quantify how much environmental impact you might have. I mentioned the impacts on neighbours, etc just for the sake of completeness. So let's do the math... Water vapour is 0.804 g/L at STP, so to get 60L (60Kg) of water, you need 74,000L of water vapour. Air is between 0 and 4% water vapour; let's use the middle just for a ballpark. So, to get 60L of water, you need to get *all* the water out of 3731343L of air. That's 3.7 cubic meters, which I agree isn't much... a layer 4cm high on the roof of your 100sg m house.

 

I wonder how efficient the condenser is? How much air do you need to pump through it to get your 60L out? Presumably that's where the energy cost is. Incidentally, condensing water out of the atmosphere should release energy at the rate of 2.27MJ/kg... a clever person would harness this energy to drive the system.

 

 


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  Reply # 1642867 29-Sep-2016 18:11
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frankv:

 

Using the sales brochure for evidence is just naive. In some countries, the evaporation rate far exceeds the precipitation rate. In those countries, you would be pushing it uphill to condense water from the air. And this kind of argument used to justify taking water out of rivers and aquifers. And to pumping CO2, and methane, and CFCs, into the atmosphere. Nothing comes for free, and nothing is unlimited.

 

I'm happy to admit that I didn't do any sums to quantify how much environmental impact you might have. I mentioned the impacts on neighbours, etc just for the sake of completeness. So let's do the math... Water vapour is 0.804 g/L at STP, so to get 60L (60Kg) of water, you need 74,000L of water vapour. Air is between 0 and 4% water vapour; let's use the middle just for a ballpark. So, to get 60L of water, you need to get *all* the water out of 3731343L of air. That's 3.7 cubic meters, which I agree isn't much... a layer 4cm high on the roof of your 100sg m house.

 

I wonder how efficient the condenser is? How much air do you need to pump through it to get your 60L out? Presumably that's where the energy cost is. Incidentally, condensing water out of the atmosphere should release energy at the rate of 2.27MJ/kg... a clever person would harness this energy to drive the system.

 

 

I think you dropped some zeros - you meant 3731 cubic metres of air (1 cubic metre is 1000 litres)

 

Doesn't matter anyway - the air moves around and you'd never create a dry zone


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  Reply # 1642973 29-Sep-2016 22:01
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shk292:

 

I think you dropped some zeros - you meant 3731 cubic metres of air (1 cubic metre is 1000 litres)

 

Doesn't matter anyway - the air moves around and you'd never create a dry zone

 

 

Yeah... I shouldn't do maths at the end of the day :) So at the end of the day, 60L of water is what's in a column of air 40m tall on top of your house.

 

If there's a breeze, you're probably right. But on a still day, you (and all your neighbours) doing that could create a pool of dry air (which is heavier than moist air) which would settle close to the ground, especially in valleys and hollows. As you say, not an issue in NZ (but that's what they said about air pollution & water usage and "sea treatment" of sewage 50 years ago).

 

 


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