Extract Water from Air: DIY Methods & Solutions

[perplexabot]

Hello all. So I am trying to see if it is possible to build a device that is able to extract water from the surrounding air. I know there are a couple of systems that already do that (based on condensation), some active and some passive, such as the atmospheric water generator (this device is tooooo expensive though) and air wells.
As little as 50mL of water per day will do (more will be better).

I read somewhere that a dehumidifier can be used to extract water from air (but that can cost around $200), worst comes to worst, i might have to go with this method.

I also read how air well's work, but cannot come up with a decent method.

Can anyone provide me with a link or method that may be able to help achieve what is needed (assuming my goal is achievable)? Primitive methods are okay as long as the system is somewhat portable.

 

[russ_watters]

Dehumidifier, not humidifier. By definition, that is the device you are looking for. There are several methods, but the most common is refrigeration.

You haven't really told us what your goal is though, so it will be tough to help without more info:
-How much water?
-What are the starting conditions of the air?
-What is your budget?
-Other constraints?

 

[berkeman]

Hello all. So I am trying to see if it is possible to build a device that is able to extract water from the surrounding air. I know there are a couple of systems that already do that (based on condensation), some active and some passive, such as the atmospheric water generator (this device is tooooo expensive though) and air wells.
As little as 50mL of water per day will do (more will be better).

I read somewhere that a humidifier can be used to extract water from air (but that can cost around $200), worst comes to worst, i might have to go with this method.

I also read how air well's work, but cannot come up with a decent method.

Can anyone provide me with a link or method that may be able to help achieve what is needed (assuming my goal is achievable)? Primitive methods are okay as long as the system is somewhat portable.

What is the range of relative humidity (RH) in the locations where you want to do this?

 

[perplexabot]

Hey, thanks for the quick replies. Oops, I meant dehumidifier, will fix OP, thank you. My goal is to use that water for plants (irrigation). According to a quick google search, the amount of water needed on average (per day) for a petunia is around 50mL (ideally I would water more than one plant, so maybe .3L for 6 plants?.. Essentially, the more the better).

I know there is a way to calculate water needed for plant (using evapotranspiration), but I feel a quick estimate just to get me started on this "air to water" device will do for now.

A quick google for my local humidity shows 9-13% moisture (would this be the 'relative' humidity you were asking about?)

Budget: less than $100 would be nice.

Other constraints:
Want to power using 10W solar panel (2 if need be) [assuming a active component]

 

[berkeman]

Holy smokes, 9-13% RH is dry! You live in a desert?

Would drilling a small well be another option?

 

[perplexabot]

Holy smokes, 9-13% RH is dry! You live in a desert?

Would drilling a small well be another option?

Ahaha. I live ~10mi from the beach. No, I can't drill. The device would have to be somewhat portable...

Is there a way to know how much water you can get from 10% humidity, on average per day?

 

[berkeman]

The wikipedia article on dehumidifiers looks pretty good: http://en.wikipedia.org/wiki/Dehumidifier

Note what it says about watering vegetables with recovered water -- probably doesn't apply to flowers though.

For the amount of water in the air (RH), see:

Engineering Toolbox -- http://www.engineeringtoolbox.com/relative-humidity-air-d_687.html

Hyperphysics -- http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/relhum.html

wikipedia -- http://en.wikipedia.org/wiki/Relative_humidity

 

[Borek]

If you are that close to water, RH should be higher than 9-13%.

 

[perplexabot]

The wikipedia article on dehumidifiers looks pretty good: http://en.wikipedia.org/wiki/Dehumidifier

Note what it says about watering vegetables with recovered water -- probably doesn't apply to flowers though.

Nice catch. I think that is a no for the dehumidifier then. I may need to use this water for vegetables. This may be harder than I thought.

 

[perplexabot]

If you are that close to water, RH should be higher than 9-13%.

If I google "humidity in Irvine," I get 10% Humidity : (

 

[berkeman]

Nice catch. I think that is a no for the dehumidifier then. I may need to use this water for vegetables. This may be harder than I thought.

Wikipedia also has info about Atmospheric Water Generator, which generates potable water:

http://en.wikipedia.org/wiki/Atmospheric_water_generator

.

 

[berkeman]

If I google "humidity in Irvine," I get 10% Humidity : (

Looks like it makes it up to 30% around 6AM though. Still, it does look pretty dry. Are there hills between Irvine and the beach?

 

[perplexabot]

Wikipedia also has info about Atmospheric Water Generator, which generates potable water:

http://en.wikipedia.org/wiki/Atmospheric_water_generator

.

Yes, I have already looked into that (as I mentioned in my OP). It costs at least $600 on amazon, that is way over my budget.

 

[perplexabot]

Looks like it makes it up to 30% around 6AM though. Still, it does look pretty dry. Are there hills between Irvine and the beach?

Yes, there are hills. But again, it has to be portable.

 

[Borek]

http://www.usa.com/irvine-ca-weather.htm

Annual average of 80.04%.

 

[perplexabot]

http://www.usa.com/irvine-ca-weather.htm

Annual average of 80.04%.

Thanks for the link. I think if this device works with the current weather, then it should work throughout the year (according to your link), roughly speaking (except for April! the graph for humidity in irvine is very interesting, something weird happens in April! anyway that is completely off topic)

Maybe somekind of primitive air well system would work?

 

[russ_watters]

Dehumidifiers do not do anything except generate heat when the humidity is low like it is in winter. Point of order though; it is absolute humidity that matters, not relative humidity. A dehumidifier's coil operates at a specific temperature, resulting in a specific dew point for the air moving over it.

What you are proposing here is an extremely expensive way to generate water. Is there a particular reason why you would not just use tapwater?

 

[perplexabot]

What you are proposing here is an extremely expensive way to generate water. Is there a particular reason why you would not just use tapwater?

No, I was just wondering if it was possible to do so with a low budget, but the more I research the more I realize this is not possible.

Actually, I just found this:
https://www.amazon.com/dp/B0069ABM7A/?tag=pfamazon01-20

I wonder if this is what I am looking for, it is cheap too. Do you think it is worth checking out?

EDIT:
It says it is around 20Watts and produces around 8oz/day (80% relative humidity). This may work, I wonder how much with the current weather.

 

[russ_watters]

Actually, I just found this:
https://www.amazon.com/dp/B0069ABM7A/?tag=pfamazon01-20

I wonder if this is what I am looking for, it is cheap too. Do you think it is worth checking out?

EDIT:
It says it is around 20Watts and produces around 8oz/day (80% relative humidity). This may work, I wonder how much with the current weather.

80% RH at 86F is extremely humid.

 

[perplexabot]

80% RH at 86F is extremely humid.

I will be satisfied if I get as little as 50mL of water. I will order it and see how much water it will yield/day

 

[berkeman]

What is 5 gallons divided by 50mL?

 

[perplexabot]

What is 5 gallons divided by 50mL?

5 gallons = 18927.1 mL

(18927.1 mL) / (50 mL) = 378.5 ?

Why?

 

[berkeman]

5 gallons = 18927.1 mL

(18927.1 mL) / (50 mL) = 378.5 ?

Why?

How often will you visit this garden?

 

[perplexabot]

How often will you visit this garden?

Say once a month, preferably less. Why ?

 

[berkeman]

Say once a month, preferably less. Why ?

378.5 / 31 = ??

Why would you not just carry out a 5 gallon water bottle to your automated watering system each month instead? It's good that you're exploring the options, but at this point, the math should be pretty clear hopefully. BTW, I have learned from this thread as well.

 

[russ_watters]

I will be satisfied if I get as little as 50mL of water. I will order it and see how much water it will yield/day

Unfortunately, you will get absolutely nothing out of it until spring.

 

[perplexabot]

378.5 / 31 = ??

Why would you not just carry out a 5 gallon water bottle to your automated watering system each month instead? It's good that you're exploring the options, but at this point, the math should be pretty clear hopefully. BTW, I have learned from this thread as well.

Ahahaha, i see what you are saying. Yes, if this "water from air" plan doesn't work, using a 5 gallon bottle or tap water will be what I will resort to. For now I still have time to see if this is achievable.

EDIT: Glad to hear you learned something too : ) Thank you for your help.

 

[perplexabot]

Unfortunately, you will get absolutely nothing out of it until spring.

First, are you saying, with complete certainty, that if I were to order that dehumidifier (link shown previously) and have it operate during current weather conditions I will get absolutely no water?

Another question, the link I provided was of a mini dehumidifier, there is another that is double the price ($88, still cheap). Here is the manual: http://www.eva-dry.com/media/rte/manuals/edv-2200-manual.pdf

It says it operates at a whopping 72Watts and produces 20oz/day at 86F and 80% humidity.
The question being, would bigger be better in this case? Would a larger dehumidifier produce more water than a smaller one under the same conditions?

Problem with a 72Watt component is I would need a ~75Watt Solar panel. That still isn't too bad.

EDIT: Is there a way to calculate how much water that machine will produce in my environment?

 

[Borek]

Check https://blumatsystems.com/category/3/Tropf-Blumat-Drip-Blumat

We used them here. They worked nicely in the winter, but were unable to keep up in the summer. However, perhaps using two or a larger model will do the trick, we never checked.

 

[russ_watters]

First, are you saying, with complete certainty, that if I were to order that dehumidifier (link shown previously) and have it operate during current weather conditions I will get absolutely no water?

There can never be complete certainty about anything, but I'm 90% sure.

The way a dehumidifier works is that it has a surface that is colder than the current dew point of the air. That causes water to condense onto the surface. A 20W dehumidifier almost certainly uses a peltier cooler (the manual you linked confirms that for the other one), which may have a pretty cool surface, but to avoid frosting over, it will have to be above freezing.

Currently, the dew point in Irvine is 34 F, which means that if the surface temperature of your dehumidifier is above 34 F, you'll get nothing. Below 32F, you'll get ice and not water. For reference, the design conditions of 80% RH at 86F is a dew point of about 80F.

It says it operates at a whopping 72Watts and produces 20oz/day at 86F and 80% humidity.
The question being, would bigger be better in this case? Would a larger dehumidifier produce more water than a smaller one under the same conditions?

Yes, of course. The difference is strictly the surface area of the cold plate, which is what water condenses on. 3x the wattage means 3x the surface area and 3x the water condensing on it.

EDIT: Is there a way to calculate how much water that machine will produce in my environment?

Yes. It is a little involved and I have to leave for work in a few min, but I'll get back to you on it.