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Water Bottle Fills Itself From the Air
mbstone writes "The Namib Desert Beetle generates water from water vapor via its shell, which has alternating hydrophilic and hydrophobic bumps which channel water droplets into its mouth. Scientists at MIT developed a self-filling water bottle using this technology, and have announced a contest for the best design of a countertop water-from-air generator."
I'm not hydrophobic, I have gay friends!
You know what they say, the bottle is half empty for pessimists and 1 year away from being full for an optimist.
Now we know what Luke Skywalker was repairing.
Need a Python, C++, Unix, Linux develop
Sounds like vaporware to me.
FTA: In the near future, it looks as if we’ll have water bottles that can capture drinkable water from the air as well.
Perl Programmer for hire
I did. It's roughly 0.7mL per hour for a 710mL coke bottle; takes around 40 days to fill it up.
There is a difference between solving a problem with physics and chemistry with materials technologies, and solving one with electrical and mechanical engineering. It's like dissing the transistor because we have relays...
Sig: I stole this sig.
Windtraps could also work using condensation techniques like refrigeration, or a regenerative moisture absorber. Of course, those techniques require power.
So does this device. From the article: "The self-filling bottle can operate using a battery or solar cell to collect and filter the water."
The air/water machine extracts water vapour via thermal methods (eg condensation).
There are of course other ways of collecting water if it is in droplet form (eg mist)
see http://en.wikipedia.org/wiki/Fog_collection or google on "fog fence"
This latter method seems to be pretty much what the beetles are doing
OTOH, my roof could easily collect more water than I use in a day.
50% or 50% empty is a misnomer. Let an engineer look at it, and he'll show you an over-engineered bottle!
How much of the world actually encounters regular airborne water but virtually no usable rain?
It's common for much of the year near coastlines but only in temperate zones, so it can only serve 40% or so of the world's population. Guess we should throw it over, like the electric car :)
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Make one that does whisky and I'm sold.
Where could you get UV light from in the desert?
Your math is off. I don't have a 710ml bottle handy, so I did a 12oz can.
Assuming 6.5cm * 12cm, ignoring the bottom and top surfaces, just the sides of the cylinder, I get 490 cm2, which is .049 m2.
3l * .049 = 0.147; 147ml/h. The can will be a 40% full in an hour, in 75% RH.
I assume the performance in drier conditions is much worse, though.
Although, once the liquid is in the container, it loses surface area? I didnt bother reading to find out whether the inside or outside or both count. math was assuming one side.. If it is the inside surface that does the work, the increasingly covered surface will give reduced efficiency as it approaches full...
shit, 2pi r h, not 2 pi d h.
so it should be 244cm2, .024m2, producing 73ml/h. Still respectable.
This is much more efficient than the fog net, principally because the arrangement of materials means that your collection surface is fouled with water less - the droplets roll straight off the hydrophobic surface, leaving the hydrophilic surface available to attract another droplet.
The same physical process is involved regardless of which air/water collection machine you use - it's all applied thermodynamics.
Like another poster said, it's like the difference between relays and transistors - they both perform the same job (being a switch) but one is a much smarter use of material science and much more efficient.
All of these calculations assume that the air, once the water is absorbed out of it, will flow out of the vessel and be replaced by humid air again at the optimal speed. It also requires power to operate. It may be that the power is used to pump the air which would mean the system has only one of these drawbacks, but the article is light on details so I can't be sure. It is also not a system that can be built at home. On the other hand I read an article by an engineer a few years ago that proposed a system that used piping running below the ground to cool the air and cause condensation, using a wind catcher at one end to push it through. His estimates included air flow and showed that a 10 meter long system could provide drinking water in desert air with a moderate wind for several people. I am unable to find the article again unfortunately.
My point is that a temperature gradient is far cheaper and available to poor third world desert countries where such a system is required. This technology is neat but not all that practical. Still a combination of the two systems, ie. lining the inside of underground pipes with this substance and letting the wind push air through might have a much higher rate of condensation and could be used for commercial and military operations in the desert.
And now imagine instead of being a bottle, it's a dense matrix made to maximize surface area and fresh air is pushed through with a solar-powered fan to accelerate the "condensation." Sort of like an evaporative cooling chiller in reverse. It could be really useful in humid tropical areas and a good alternative to desalination plants.
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