Air Well - collecting water from the air

Joshua Myrvaagnes wrote:

Why do you ask, is there something you need to modify or just avoiding building something tall that could fall over?

I have an idea for a portable peasant's air well for watering plants. I haven't quite formed the idea enough yet to share, and it certainly wouldn't be suitable for drinking water. However, the theory is it will help the plants around it grow during our drought, so I've made a couple and put them in the field (one near lentils, one near barley - both have roots that establish during the rainy season) to see if it improves the yield compared to the rest of the row without air wells.

That's really where our water shortage hits us. We have ample well water for humans, critters, and the kitchen garden, but I want to grow some staple crops in an area with excessively good drainage during the drought. This is where I think peasant air wells might help the most (coupled of course with soil improvement, terracing and other permaculture techniques)

from the Warka Water site:

Some areas may have more favorable conditions than others. However, air always contains a certain amount of water, irrespective of local ambient temperatures and humidity conditions. This makes it possible to produce water from air almost anywhere in the world. Locations with high rates of aerosol and humidity are best to install a condenser.



sounds like it works best in fog; they don't have specific numbers yet, 100 litres/day seems to be in ideal conditions only. But if you can get 5 and that's what that gimungo stone air well was doing per day then that's amazing.

We have a very heavy dew for the first four or five months of our drought, so I'm hoping air wells might do the trick.

To be completely honest, my brain has glossed over air saturation temperatures, &c. I knew it all once, but where the devil I hid that information in my brain is a mystery to me. Basically, all I want now is a practical application. We get dew, so if I pile rocks on the south (or perhaps the east) side of the tree, it increases the tree's chances of surviving the drought. Things like that.

Steve Farmer wrote:Just found this thread and it's prompted me to rekindle some ideas I have had in mind for a while.

Firstly want to say that there is no point warming up the air before you condense it. Yes while warmer air has more capacity to carry water, that only matters when it's picking up water, eg when its coming over the sea. Once you're about to condense the water vapour you want to cool it. If you heat it, the amount of water in the air will stay the same, but its relative humidity will decrease, and you will require more energy to cool it.

>>Are you sure about that part? doesn't warmer air have more capacity to absorb water, and therefore absorb more of the water from the cooler air around it (that's farther from your collector)? does anyone who really knows the physics of this want to clear it up?

I have condensation on my window right now, and the window is about room temperature (70 degrees) and the air outside is getting hot from the sun. The sun hasn't hit the window itself yet, but before it got warmed over there was there condensation? I'll have to observe tomorrow morning.




Here's my earliest idea on how to condense water out the air.

Have an enclosed sump/tank of water, enclosed to stop evaporation, and must be in a cool location so possibly underground but at very least in the shade.
Have a connected shallow pond, say 1 cm deep, but with a large surface area. Should also be in the shade but must be exposed to ambient air.
Have the ambient air monitored for humidity and temperature as it comes across the shallow pond.
If the temp of the water in the sump is below the dew point of the ambient air, the pond is filled by pumping from the sump.
If the temp of the water in the pond rises to the same as or above the dew point, it is pumped back into the sump.
So we have a dew pond that is full when it would collect water, and evacuated when it would evaporate. As long as there is no significant change of height between the two then pumping would be very cheap and quick, could be run from a small solar panel.

This idea sounds really interesting, but I didn't quite get it, and it seems like it would lose a lot of water to evaporation? can you make a diagram? maybe th'ats already been answered, haven't read the whole thread yet. thanks!

Joshua Myrvaagnes wrote:it seems like it would lose a lot of water to evaporation?

The water is only exposed to the air when the temp is below the dewpoint. Under these conditions there is no evaporation, only condensation.

Cool! That's brilliant.

Steve Farmer wrote:

Joshua Myrvaagnes wrote:it seems like it would lose a lot of water to evaporation?

The water is only exposed to the air when the temp is below the dewpoint. Under these conditions there is no evaporation, only condensation.

R Ranson wrote:
I have an idea for a portable peasant's air well for watering plants. I haven't quite formed the idea enough yet to share, and it certainly wouldn't be suitable for drinking water.

That sounds very, very cool. Consider this encouragement to further develop the idea to the point where you can share it. : )

Geodesic dome shelters are widely known for collecting to much condensation if not vented properly. Rocket Mass Heaters also expell steam. I wonder if we could use this guys take on running copper pipe through the ground in a spiral to collect all of this condensation! I bet if one would be so inclined to bend some copper pipe inside of a PVC pipe for the downward spiral into the ground that the copper pipe could collect condensation on the inside and outside of the pipe thus making it more efficient. Using a ventilation turbine as previously mentioned in this post could also prove useful for sucking the air through the pipe and ventilating any evaporation from the well in the ground.
I am currently making a geodesic dome out of 1" EMT and do not have funds to test this idea at the moment. I shared the video to keep the cog wheels in our mind turning Perhaps someone does have the time/funds to test it (or would like to recruit me into there intentional community to test it for them *wink wink*).

Destiny Hagest wrote:This is something they'll actually be building during the upcoming PDC and Appropriate Technology courses at the Lab this summer - in this dry Montana climate, I'm really anxious to see this design in action and track how well it performs.

Link to PDC course Wiki

Anyone have an update? Are there podcasts about this ATC?

I could be wrong (I wasn't there), but I think they didn't have time to build an airwell - apparently Tim covered so many topics in his workshop, I seem to recall they were just overwhelmed with projects and experiments and didn't get to it :/

A drawing of a simplified johnson style air well

Comments re atmospheric condensers, based upon notes I’ve collected over the years.

Basically it is necessary to cool the air to the "Dewpoint".  All of the devices on the web appear to rely on night cooled mass to provide the needed temperature difference, yet leave the device open to daytime heating by the sun.  Granted, I find indications that even in the daytime in certain conditions it might be possible to radiate to the sky 100 to 200 BTU per hour, which strictly in math could represent 1 pint or so of operation for every 10 square foot or radiation area.

But.  

Once the water has condensed the "dry" air, now cool, needs to be exhausted.  This points out the flaw in all of the “air well” devices I have seen. None of them provide for heat exchange directly between the incoming and outgoing air , therefore the "coolness", essential to precipitation, imparted to the incoming air is directly exhausted, and rapidly eroded.

Ideally, there should be sufficient heat exchange between intake and exhaust air that at the pipe open ends, they are virtually at the same temperature, despite being cycled thru a chilled spot.  The transition between liquid and vapor water is, absent unknown science or magic, a matter of the transfer of 970 BTU per each pint condensed.  (7760 BTU per gallon)  

Assume a Tucson fall day with a relative humidity of 7%. There is roughly 7% of 8.8 grams of water in each cubic meter of air (.616 gram).  Lower the temperature to 66 F, and relative humidity doubles to 14%.  Lower the temperature to 48 F, and relative humidity again doubles, now to 28%.  

If we cool air without changing its moisture content, eventually we'll reach a temperature at which the air can no longer hold the moisture it contains. Then water will have to condense out of the air, forming dew or fog. The dewpoint is this critical temperature at which condensation occurs.

But, water does not immediately change state as the temperature reaches the "right" point.  The "Latent heat of condensation" (Lc) refers to the heat that must be removed from water vapor for it to change into a liquid. Lc=2500 Joules per gram (J/g) of water or about 600 calories per gram (cal/g) of water.

Specific heat is defined as the amount of heat energy required to raise 1 g of a substance by 1° Celsius.  If the specific heat of air is .25 calories per gram of air per degree C change, then each degree C change in a cubic meter represents 323 calories.  The specific heat of water is 1 calorie per gram per degree C.  In our Tucson fall day above there was .616 grams of water in a cubic meter of air.  Air and water vapor together take a change of about 324 calories per degree C.  We need to lower the temperature by around 40 C, or get rid of 12,960 calories of heat to reach the dew point.  An additional 379 calories of heat needs to be removed to compensate for the latent heat of condensation, for a total of 13,339 calories.

Presenting numbers for perspective.  Assume a daily water need of 174 gallons (658.6 liters) - 658,660 grams of water.  In a Tucson fall day, each of us would need to "wring" all of the water out of more than a million cubic meters of air  (1,069,252) - a cube 100 meters on a side.  If the cross section of the cooling tube is a meter, and the device operates 24/7, and the device is 100% efficient, the required flow rate is 12 meter per second.  DON’T panic, that’s only about 28 mph.  At that speed though, the air must stay in the chilled zone long enough for the vapor to condense.  

The heat to be moved is about 14 billion calories.  (55.6 million BTU) The water portion of this number is about 450 million calories (1.8 million BTU).  Depending on device efficiency, SOME part of the other 1 billion calories should be able to be conserved in a heat exchanger.

Another approach.

Increasing the pressure also changes the dew point.  Double the pressure and relative humidity doubles.  Assume normal atmospheric pressure of 14 PSI.  Pump the fall Tucson air into a tank at 28 PSI and the relative humidity inside is now 14%.  Make it 56 PSI - 28%.  102 PSI - 56%.  204 PSI - 102%, and you've got water accumulating in the bottom of the tank.  

This is a subject I am very interested in, since its pretty dry here.

"Prehn Method" - https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0ahUKEwiMnpGu6sjZAhUF-6wKHQ7WBo8QFgg_MAM&url=https%3A%2F%2Fpermasteader.com%2Fwp-content%2Fuploads%2FWater-From-the-Hills_Prehn-Method.pdf&usg=AOvVaw1BlBUkmhZoRkSA32_Gmrme  

Water is captured from the air on the African coasts. A wall of either plastic netting, safety mesh is strung between poles in areas where mists come through.
The moisture is captured on the mesh and drained to a useful spot. Prior to plastic I believe plant material was used.

I've been researching yakchals
. They have been used in Persia for a long time. I want to try something like this is Joshua Tree, CA someday.

They use cooling towers as well. The moisture (even in dry climates) will cool rapidly as it travels down the tower, before condensing on the inside of the yakchal. It eventually will help to replenish groundwater and can be captured as well. The base of the yackchals can get so cold that it can keep food at near-freezing temps.

Updated video on the Warka bamboo vapor condensing tower.

http://https://www.theblaze.com/video/watch-this-bamboo-tower-creates-26-gallons-of-water-a-day-from-thin-air

Richard Presley wrote:Heard this on NPR about "fairy circles" in the desert: http://www.npr.org/2013/03/28/175369153/whats-behind-the-fairy-circles-that-dot-west-africa


Interesting how many different ideas tap into the same basic concept.

These remind me of grass rings around ant piles...

I am interested in a device to collect moisture from air for Potable water.  We have no well & need water. I would like to know where I would purchase a unit & the cost?
Than you:
G. Autumn Venezia
horseplay54@gmail.com
518 873 1011

Cristian Lavaque wrote:Related: Dew ponds



http://www.rexresearch.com/dewpond/dewpond.htm

Neolithic Dew Ponds and Cattleways by Arthur Hubbard & George Hubbard
http://archive.org/details/neolithicdewponds00hubb

http://google.com/search?q=dew+pond&num=100&tbm=isch

How did they keep these from becoming mosquito havens?

Hey All,

Question,
Why do non of the listed designs use or account for water molecules having charges?

I think its an incredibly important aspect of water vapour!


Statement!

I would also like to advice caution when reading some of the posts in this forum, I am not trying to put anyone down!

My reasoning is because of scammers using unfounded claims about air water harvester, to take advantage of naïve yet well meaning people!

I would not want anyone to be taken advantage of! So please be wise about claims made about air water harvesters!

Kind regards,
Alex

Very interesting

Gina Cardoza wrote:Wouldn't the weight of a lot of rocks next to plants/trees compact the soil and harm the roots?

Apparently not. I discovered the principle of water collection via rocks accidentally here in high-altitude western New Mexico.  As I scoop horse poop I toss rocks I pick up with the manure rake into loose piles outside the horse pens, meaning to move them someday. Not even piles, actually -- just a bunch of rocks in one spot.  Those spots grow dense "weeds" every year.  The first year I kept them because I enjoyed the wildflowers.  After that first year, though, I added to the piles.  Now I create piles on purpose.  Any soil compaction is minimal.  In fact, when I do this in bare areas where the horses have already compacted the soil, the rocks allow the soil to decompress.

I also places larger rocks -- maybe the size of large loaves of bread -- in rings around tree seedlings to support and protect them, and provide wind breaks.  When the trees are large enough they just push the rocks aside.

[quote=Alex Moffitt]...I would also like to advice caution when reading some of the posts in this forum, I am not trying to put anyone down!
My reasoning is because of scammers using unfounded claims about air water harvester, to take advantage of naïve yet well meaning people!
I would not want anyone to be taken advantage of! So please be wise about claims made about air water harvesters!...[/quote]

So true!  A few years ago I invested in a heavily advertised and highly recommended Kickstarter for a water harvester that might or might not work.  After lots of money was collected (well above their advertised budget) there were a few updates and then nothing.  No answers to emails or any other inquiries.  I think the claims for what it would do were accurate enough and I think some water could be harvested using their design, but I also now think they used other people's research to get investors and never intended to construct the harvester.

Hans Kristorff - How steep is the slant of your roof? I'm in western WA and would like to incorporate this into the house I'm planning to build.

This company was involved with Kickstarter, I hope they are credible, www.warkawater.org
They have water from air projects and also a series of documemtaries on youtube.

Stretch a tarp on four posts  five feet above the ground and place a stone in the center. Place a container on the ground under the stone to collect the condensation

Jennifer Jennings wrote:Tom Brown uses a method similar to the Waterboxx for getting water out of the earth via condensation.  Basically, you dig a hole, place a container in the center at the bottom, and cover the hole with a piece of plastic secured around the edges with dirt & rocks. Placing a small rock in the center of the plastic creates enough of an angle for the condensate to drip into the vessel below.

Adapting the rock pile idea to keyhole beds and other masonry edged beds is really a no-brainer, and kinda already standard practice. One more reason to use and reuse local materials for conservation!

John C Daley wrote:This company was involved with Kickstarter, I hope they are credible, www.warkawater.org
They have water from air projects and also a series of documemtaries on youtube.

Red flag! It looks like a scam!

Alex, what are the red flags you speak of?

John C Daley wrote:Alex, what are the red flags you speak of?

Photo shopped images on website,
qualifications of staff miss spelled.
The faqs of productivity being random questimations without calculations.
The lack of the company doing its own research, but relying on others groups to do so.
Lack of updates and transparency.
Repletion that it works without demonstrations,
to quote a number of hydrologist the design does not add up.
Also look at the sanitation designs and other designs, they are clearly not going to work.
To quote the bill gates foundation, warka water has had to many false dawns, to consider.
The false dawns, are because it does not work, and over how many years have they claimed it works, with how many different values.
a respectable organisation claims it does not work, yet warka water is saying it does work?
if it doesn't work why are they supposedly charging 1600 to build them, for donators? Hmmm.
The photos trigger me of how sceptical the people in the Africans in the photos are, it is not how they act when they trust people and are happy?
Online activity and demonstrations of work, something all charities do, to say we are doing good work give us more! which warka water is not doing, that is a red flag.
lack of hydrologists in the team,
Lack of offices or cities where the actions of charitable work is being organised from?
The speed of the supposed development of the warka water tower. It takes months and years to develop a invention to production stage, except elon musk, because of resources and teams!

In short it does not work and it will never be built!

I can continue with more!

Alex, you may well be correct.
But I also work in that field but I am a Civil Engineer not a Hydrologist.
The collection of water from fog etc is a well practised concept.
In my experience there is nothing patentable, and experience shows it work so there is no need for 'research'.

As I see it its just a matter of producing towers from local materials and adding the mesh.
In old times mesh was made from rope or bamboo strips.
So some of it looks ok.

Mind you if the Gates Foundation has concerns then you are right to call them out.
just to clarify the situation.

John C Daley wrote:Alex, you may well be correct.
But I also work in that field but I am a Civil Engineer not a Hydrologist.
The collection of water from fog etc is a well practised concept.
In my experience there is nothing patentable, and experience shows it work so there is no need for 'research'.

As I see it its just a matter of producing towers from local materials and adding the mesh.
In old times mesh was made from rope or bamboo strips.
So some of it looks ok.

Mind you if the Gates Foundation has concerns then you are right to call them out.
just to clarify the situation.

Fog collection methods work, but the methods used by warka water are completely different.
Saying that Fog collection is proven to work, correct,
But it does not equate to fog collection working for warka water!

A works
does not equal B works!
especially when the processes used in B are extremely different to that of A.

OK I will have another look, to see what you see. Thanks

Alex, I am not sure about your assertions.
- photoshop is often used
- I saw no list of qualifications, just a qualification title
- I see no spefic design for the sanitation system other than drawings, which show a standard sytesm anyway.

I think you are noit correct.
I search widely to find any comments that agree with you and `i found nothing.
Can you produce something iother than you own opinion?
Thanks

Hello,


I would like to move the warka water, posts to the Cider press, and continue the conversation in that location on warka water!

kind regards,
Alex

Why?
That action would restrict legitimate talk, if you want to dump om that company, just signal you think there products in your opinion dont work.
Others who may not agree can form their own opinions.