Saturday, April 15, 2017

How much energy to get water from atmosphere?

Can this be calculated?

There was a thought about this yesterday, but I gave it up when I realized how much energy would be required.

For the record, I wanted to use a rough guesstimate of the energy requirement from this BTU calculator.

Next thing, I wanted to use relative humidity figures.  But that is not useful, or so I found out.  It so happens that air will not hold that much water per cubic meter.  Furthermore, to lower the temperature to dew point, as would be required in order to condense it, would take an enormous amount of energy.

Therefore, the BTU calculation would not be useful.  But the volume of air calculation would be.

Just for grins, I plugged in one cubic meter for the volume.  I got this:

At one hundred degrees farenheit, and twenty per cent humidity, the dew point would be fifty degrees less, or about fifty degrees.

Interesting.  That would mean that you could get condensation using only 650 watts.  How much water is the question.  The device mentioned in a previous post said just short of three liters per twelve hours.  That's a liter every four hours.  Not much water.  That would require two and a half kwh.   That's quite a bit of juice for just one liter.

I could try this experiment in the desert, but if this is what I could expect, it may not be worth it.

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