Cool concept. As they mention, more work needs to be done on long term durability, although they saw no degradation in their (very short) testing period. To me, the humidity control seems more worthwhile/useful than the power generation, although that could be a useful solution for small IoT devices like door and window sensors that don't need much power.
I like it as a proof of concept, would love to see a more serious engineering effort to demonstrate what real world costs, durability, and aesthetics might look like (if significant portions of indoor walls are going to be covered in this stuff, it needs to be able to look decent).
Typical 50% RH at ground level is ~7g/kg air, air is roughly 1kg/m^3, so between the surface and the planetary boundary layer (let's say 1km) is about 7L of water per m^2 of surface. Moving along at ~3m/s means 21L/s passes by each meter of fence line.
PBL probably mixes after about 50km, so it takes ~5 hours to normalize after you pull out water at ~5 knot wind speed. If you want to not make a dent, means you can pull less than 1L per m^2 per hour, or about 8m^3 pear, which is about 8x the yearly requirement for farmland.
So, you can irrigate a farm and your neighbors would mostly be fine.
In humid regions, there is no practical limit that would cause any noticeable effects on the humidity of outdoor air. There is just so much water in the air that even if you were running dehumidifiers across all available land area, the air is still going to feel humid.
It would probably depend on how you use the water. Watering plants (including via gray water systems) would mean a lot of the water would evaporate or transpirate. Flushing it down the drain means it exits the system.
For non-potable use, probably. Potable use might require some more treatment checks on it. It's one thing to use it for flushing the toilet... showering might be ok. Not sure about washing dishes. Washing clothes, maybe.
And for the "the amount of times I change out 2 gallons of water from the dehumidifier in the basement in the summer"... there's a lot of moisture out there.
This is constrained by season. In the winter, its much easier to get to 0% humidity than it is in the summer.
> We’ll imagine our storm measures 100 kilometers on each side and has a high TPW content of 6 centimeters. This means the water in our rainstorm would have a volume of: 100km x 100km x 6cm = 0.6km^3
> That water would weigh 600 million tons (which happens to be about the current weight of our species). Normally, a portion of this water would fall, scattered, as rain—at most, 6 centimeters of it.
Change that to 4cm for current conditions... but that's a lot of water.
That has a table of how much water at different humidity and temperature combinations. It's currently about 20 °C and that gives us 15.6 g/m^3.
... but there's an awful lot of air around.
This can also be complicated if you have trees or other vegetation around. The humidity at my parents place (fairly deep in the woods in farmland) is always much higher than it is if you go to the road (or in town).
> Some research conducted by USDA Agricultural Research Service suggests that corn can contribute between 3,500 and 5,000 gallons of water per acre to the atmosphere over the course of one to two days. A typical pool contains 18,000 - 20,000 gallons.
...
So, it's complicated. Maybe, a little bit, depends on where you are.
The condensate (water vapor that gets condensed out of the air in the process of generating the electricity) has to go somewhere; if it's not properly handled, yes, I would expect mold.
I like it as a proof of concept, would love to see a more serious engineering effort to demonstrate what real world costs, durability, and aesthetics might look like (if significant portions of indoor walls are going to be covered in this stuff, it needs to be able to look decent).
isn't below 40% "bad"?
Turn myself into a moisture farmer if you will.
But then I wonder, would it be a problem if everyone did it? Would it cause humidity to drop in a bad way?
Typical 50% RH at ground level is ~7g/kg air, air is roughly 1kg/m^3, so between the surface and the planetary boundary layer (let's say 1km) is about 7L of water per m^2 of surface. Moving along at ~3m/s means 21L/s passes by each meter of fence line.
PBL probably mixes after about 50km, so it takes ~5 hours to normalize after you pull out water at ~5 knot wind speed. If you want to not make a dent, means you can pull less than 1L per m^2 per hour, or about 8m^3 pear, which is about 8x the yearly requirement for farmland.
So, you can irrigate a farm and your neighbors would mostly be fine.
(math not checked)
And for the "the amount of times I change out 2 gallons of water from the dehumidifier in the basement in the summer"... there's a lot of moisture out there.
This is constrained by season. In the winter, its much easier to get to 0% humidity than it is in the summer.
https://tropic.ssec.wisc.edu/real-time/mtpw2/product.php?col... for the total precipitable water over North America. Through the midwest, it's in the 40-50mm range.
Consider XKCD's giant raindrop - https://what-if.xkcd.com/12/
> We’ll imagine our storm measures 100 kilometers on each side and has a high TPW content of 6 centimeters. This means the water in our rainstorm would have a volume of: 100km x 100km x 6cm = 0.6km^3
> That water would weigh 600 million tons (which happens to be about the current weight of our species). Normally, a portion of this water would fall, scattered, as rain—at most, 6 centimeters of it.
Change that to 4cm for current conditions... but that's a lot of water.
https://en.wikipedia.org/wiki/Humidity#Relationship_between_...
That has a table of how much water at different humidity and temperature combinations. It's currently about 20 °C and that gives us 15.6 g/m^3.
... but there's an awful lot of air around.
This can also be complicated if you have trees or other vegetation around. The humidity at my parents place (fairly deep in the woods in farmland) is always much higher than it is if you go to the road (or in town).
https://extension.osu.edu/about/resources/corn-sweat-and-hum...
> Some research conducted by USDA Agricultural Research Service suggests that corn can contribute between 3,500 and 5,000 gallons of water per acre to the atmosphere over the course of one to two days. A typical pool contains 18,000 - 20,000 gallons.
...
So, it's complicated. Maybe, a little bit, depends on where you are.