Making an air well

I was thinking about another fun project that draws water out of the air with just the sun's energy. I noticed the empty open vinegar bottle I washed and set to dry on my window sill accumulate more moisture every day. It was pooling water in the bottom after a week. The bottle shape is like a ball with a long spout. I read a little about air wells on the web, but they are very large structures. It would be fun to build a small one that would make a few glasses of water a day. Comments?

Here's one link Air Wells & Dew Ponds

Picture of Making an air well
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I was looking into this as a glass design graduate student in 2011. I was trying to develop a product that would collect fog, was portable and could be placed directly over crops. The design I came up with was too expensive to produce a prototype. But two years after i graduated I came up with a compromise; a car or minivan's back windshield mounted on a post using it's window wiper hole as the anchor point and turned in the opposite direction, (parabolic surface facing the wind) with some sort of gutter to collect the water and a hose to direct it towards the plants you want watered. I have yet to build one because we don't even get enough fog in SF anymore to be useful but if you do, that might work for you?

Orngrimm3 years ago
Thanks for the thread! I think the whole air-well-idea is very interesting! :)
A lot of informations about different approaches can be found on the web.
btrias3 years ago
How about a recipient with a hour-glass shape? The bottom half in the ground or insulated so the collected water is not heated again and the top half solar-heated. The question remains how to create air circulation.
adrofig5 years ago
I would try having a large bottle and a smaller bottle. Fit the small bottle inside the large one. Fill almost all of large bottle with water. Water cools slower than air so it will increase the rate of condensation. A metal cone could also be added to the smaller bottle to speed condensation. My idea was to have it put in a car and have the a/c run over the external of the reservoir to cool the water and then have it stored in the car for drinking water. If you did that it would solve bringing a water bottle in your car but then it getting warm.
jjmmjj7 years ago
See the Wikipedia article:
Let's try that again. See the Wikipedia article on air wells, its full title is:Air well (condenser).
I think existing airwells work by two principles. One type takes advantage of seasonal temperature differences; summer vrs winter. This type works by cycling the surface air thru pipes or rooms underground. The other "standard" type takes advantage of the difference in day/night temperatures. The salad dressing bottle appears to be functioning as this type of airwell. Dew on the windshield and "bridges may be icy" are examples of this type of air well. I suspect that "dew ponds" work on this principle. Dew ponds have a long history, perhaps dating back to the Neolithic. In "Naturalist on the Thames" the author described a dew pond that produced upwards of five acre-feet of water a year... unfortunately he didn't give the dimensions of the pond. Russell's "improved dew reservoir" is 900 square-feet and five feet deep; deep enough that it may work on the summer/winter temperature differential instead of the day/night temperature differential. Either way, it only produces a tenth the water recorded by Cornish in "Naturalist on the Thames".
robbtoberfest (author)  airwelldriller7 years ago
Awesome info, Thanks! I still have this project on my list and plan to do an instructable on it someday.
trebuchet039 years ago
I came across this a few weeks ago....

Water Cone

Compact and lightweight - I think they can be stacked and I'll bet you can get higher efficiency if you insulate the bottom pan :) If I were to make one, this is the design I'd try to replicate :P

1-1.7L per 24 hours. That's 4+ to 7+ glasses per day :)
PKM trebuchet037 years ago
For added irony and "fight the powah" points, I'm sure you could make one of those out of the neck of a water cooler bottle :)
robbtoberfest (author)  trebuchet039 years ago
Would that setup draw water out of the air? I'm not quite getting it. Maybe if the caps were left open. I think the heat build up in the bottle makes water condense during the day and slowly exhausts the hot air, then at night the bottle draws in with cool moisture laden dense air for reheating and condensing the next day.
Slaps hand to forehead... I misread what you were saying :P No, this you're supposed to pour in sour water (be it salt water or muddy water etc.) and then fresh water forms on the outer ring.
robbtoberfest (author)  robbtoberfest9 years ago
Reading more on this, I would need a pile of rocks 10' sq and 8' tall to make .5 gal at day. This might be a lost cause for now. I can't put out that kind of effort right now, but maybe someone else can.
bobolou29 years ago
where i live it is often very foggy sometimes in the morning. Perhaps if you strechted a thin peice of cloth between two poles with something similar to a roof gutter benaeth it. The water in the air would drip down the cloth into the gutter. You could put a bunch of these in series and get a considerable amount of water...... maybe i will try this.
You are describing a "fog fence". A fog fence uses two layers of plastic cloth between the poles. The water that beads on a single piece of fabric don't bead up enough to run off. Given the slightest eddy, the two layers of fabric rub against each other causing the water to bead up and run off. At least one village in South American gets its water from a fog fence. I'm not sure a fog fence is actually an airwell, since it does not manipulate the local temperature to harvest water where none would otherwise be.
I don't know if they still do it, but they used to "farm" fog on the Canary Islands.

The islands are small, too small to generate rain, but they do have foggy weather.

"A standard fog collector consists of a 1m x 1m frame raised 2m above ground level which supports a double layer of (locally available) polypropylene plastic mesh netting. As fog touches the netting drops of liquid water form, which run down the nets into gutters that direct it into suitable containers."

Link to fog-farming project on Lanzarote
Link to magazine article with image of collector

Apparently the collectors are good for several litres of water per square metre per day
Patrik8 years ago
Try putting some aluminum foil around the bottom of your vinegar bottle, to protect the accumulating water from getting heated up and evaporated again by the sun. What kind of material is the windowsill made of? I assume a marble windowsill would keep the bottle cooler than a wooden one, for example.