Atmospheric Water Generators

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Linuxluver

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Topic # 204274 24-Sep-2016 17:56

We're thinking of building a home / holiday bach in a remote location and one of the issues we would face is water. If it doesn't rain, we don't get any and we either need to be near a ready source (a river / stream) or have it delivered by a truck to a large tank.

I don't really want to do any of that. I'm not a fan of roof water anyway...as I know too many people in the Horowhenua / Manawatu who died of bowel cancer.....maybe after drinking spray drift of all kinds for years.....delivered via their roof to their water tanks.

I'm looking at atmospheric water generators. For example, the "Skywater 500 Alternative Energy" unit. It can produce (approximately) 378L of water / day under ideal conditions, but even half that would be acceptable most of the time. We would use some and store the rest. After a days or few weeks we would have a large reserve of clean water in a tank for all usual uses: cooking, drinking and some washing.

This particular unit uses about 4.2kw of power and that would require a fair amount of solar or wind energy.....in addition to other requirements.....but it would be do-able.

Ideally, I would have two smaller units so if one breaks down I'm not left with no water at all. There are other units ("WaterMicronWorld", Konia") but no one in NZ seems to sell them, Not that I can find.

A unit that can produce 1,100 gallons (3,800-ish litres) is about US$32,000....and would be far more than we needed it.

This setup may be a lot more expensive than a truck delivering water.....but it would mean I don't need to rely on a truck delivering water (with e-coli or whatever else in it).

Anyone know of anyone in NZ doing this? In India it's rapidly becoming an important source of water as climate change dries up the rivers in many areas.

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Reply # 1639958 24-Sep-2016 18:27

Looks like they need circa 24 degrees to work based on the link...

Do they not work once it gets too cold? you may end up with lots of rain water but too cold to extract any from the air.

Being targeted to India suggests NZ climate may not be very suitable..

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kiwirock

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Reply # 1639962 24-Sep-2016 18:53

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This sounds like a 4.2KW dehumidifier.

You'll still get dust and dirt and what not on the condenser coils. So how does this unit stay free of mold, fungi, dirt and dust?

The volume of air, heat of the air and need for high humidity would be the only way to reach it's optimum capacity.

I'd probably stick to rain water and just filtrate/UV sterilise and if that paranoid, distill any drinking water. Way less energy requirements.

Bowl cancer rates are high in this country regardless of tank water. Usually because we eat to much meat in NZ. Like cold left over sausages for snacks in the fridge.

You can make distillers out of some interesting DIY contraptions like mirrored reflectors on dishes and black boxes with glass etc...

However, are you a plug it in metro person that calls a house a batch or a DIY'er?

neb

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Reply # 1640313 25-Sep-2016 18:34

kiwirock:
This sounds like a 4.2KW dehumidifier.

You'll still get dust and dirt and what not on the condenser coils. So how does this unit stay free of mold, fungi, dirt and dust?

+1. You definitely don't want to drink dehumidifier condensate. What about using a heatpipe solar array as a heat source, or at least a starting point, towards distilling whatever nonpotable water might be available?

Linuxluver

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Reply # 1640325 25-Sep-2016 19:36

mentalinc:

Looks like they need circa 24 degrees to work based on the link...

Do they not work once it gets too cold? you may end up with lots of rain water but too cold to extract any from the air.

Being targeted to India suggests NZ climate may not be very suitable..

The production would be reduced, but as long as it's above freezing, you'd get some water. Perhaps a good reason to buy a larger unit than required so that in marginal conditions you can get a minimum.

I'm ok with rain water......it's the other stuff on the roof and in the gutters I'm not a fan of. I'd filter it and irradiate it and then carbon filter it....done this before....but this doesn't address whatever is in solution in the water. Living in Foxton years ago the dairy farmerswould spray pesticides and fertilisers....and they drifted across my property. But I had bore water there.

My sister in law used to live in Kaitaia and would drink tap water from the tank. I lifted the cover on it once there were frogs living in there. I didn't fancy drinking frog urine / feces and their decaying remains......plus all the other wildlife in there with them.

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Linuxluver

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Reply # 1640327 25-Sep-2016 19:41

kiwirock:

This sounds like a 4.2KW dehumidifier.

You'll still get dust and dirt and what not on the condenser coils. So how does this unit stay free of mold, fungi, dirt and dust?

The volume of air, heat of the air and need for high humidity would be the only way to reach it's optimum capacity.

I'd probably stick to rain water and just filtrate/UV sterilise and if that paranoid, distill any drinking water. Way less energy requirements.

Bowl cancer rates are high in this country regardless of tank water. Usually because we eat to much meat in NZ. Like cold left over sausages for snacks in the fridge.

You can make distillers out of some interesting DIY contraptions like mirrored reflectors on dishes and black boxes with glass etc...

However, are you a plug it in metro person that calls a house a batch or a DIY'er?

The web site shows the units filter and purify the water captured via condensation.

I don't require the optimum capacity. About half that would be adequate.

I agree distillation sounds good. But it's slow. 1L / hour....maybe...and they aren't typically set up to do more than fill a pot. Osmotic filtering is also good, but again, slow.

I'm more a DIY type. But time and circumstance do often mandate some plug-it-in time-saving. :-)

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Linuxluver

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Reply # 1640328 25-Sep-2016 19:42

neb:
kiwirock:

This sounds like a 4.2KW dehumidifier.

You'll still get dust and dirt and what not on the condenser coils. So how does this unit stay free of mold, fungi, dirt and dust?

+1. You definitely don't want to drink dehumidifier condensate. What about using a heatpipe solar array as a heat source, or at least a starting point, towards distilling whatever nonpotable water might be available?

The unit purifies the water.

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elpenguino

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Reply # 1640353 25-Sep-2016 20:42

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you dont need purified water to wash your clothes and have a bath ( do you?) so you could still use roof water to flush the loo and so on.

Since this system would be purifying the water, why not just purify drinking/cooking water from roof water through a similar regime?

BTW according to a research paper i saw years ago, the biggest health risk from roof water is from bird poop - ideally you don't catch the first rain with all the gubbins it flushes off the roof.

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Reply # 1640361 25-Sep-2016 21:02

elpenguino:

you dont need purified water to wash your clothes and have a bath ( do you?) so you could still use roof water to flush the loo and so on.

Since this system would be purifying the water, why not just purify drinking/cooking water from roof water through a similar regime?

BTW according to a research paper i saw years ago, the biggest health risk from roof water is from bird poop - ideally you don't catch the first rain with all the gubbins it flushes off the roof.

You need one of these :http://www.marley.co.nz/products/rainwater/rainwater-accessories/first-flush/

neb

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Reply # 1640395 25-Sep-2016 21:53

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Linuxluver:
My sister in law used to live in Kaitaia and would drink tap water from the tank. I lifted the cover on it once there were frogs living in there. I didn't fancy drinking frog urine / feces and their decaying remains......plus all the other wildlife in there with them.

Stayed in a small village in Saxony once not long after the wall came down and was offered well water to drink and shower in. Said I'd rather listen to heavy metal than drink the stuff...

Aredwood

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Reply # 1642184 29-Sep-2016 00:37

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First of all, look up the yearly rainfall totals for your area. And measure the plan area of your roof. On a 100m2 roof, every 10mm of rain gets you 1000L of water. Lowest total cost of production will definitely be lots of rainwater tank capacity. Plenty of people on trademe selling whole house filter systems including UV treatment. More roof area and more storage easily solves the not enough rain issue (within reason)

Myself - I have rainwater tanks as I don't like the taste of towns supply water - High mineral content. As Watercare increase the PH and increase the mineral content to get some extra life out of their 100+ year old cast iron pipes. And all of their asbestos cement pipes. Run the water through a 1 micron sediment filter - whole house. And have a combination carbon block and KDF filter for the kitchen sink and icemaker fridge. Rainwater has a naturally very low mineral content. Meaning I like the taste, and a side benefit is that soap bubbles up more.

As for that skywater unit - it didn't say if the 4.2kW power consumption was a continuous draw. Or if they meant 4.2kW/hr per day. If that is continuous - it is just over 100 units per day - crazy high power consumption. Even if it is 4.2kW/hr per day. You will still need a really large off grid system to provide for that demand. I can't possibly see how a skywater unit could ever be sensible. Especially from an environmental point of view.

Linuxluver

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Reply # 1642270 29-Sep-2016 08:24

Aredwood:

First of all, look up the yearly rainfall totals for your area. And measure the plan area of your roof. On a 100m2 roof, every 10mm of rain gets you 1000L of water. Lowest total cost of production will definitely be lots of rainwater tank capacity. Plenty of people on trademe selling whole house filter systems including UV treatment. More roof area and more storage easily solves the not enough rain issue (within reason)

Myself - I have rainwater tanks as I don't like the taste of towns supply water - High mineral content. As Watercare increase the PH and increase the mineral content to get some extra life out of their 100+ year old cast iron pipes. And all of their asbestos cement pipes. Run the water through a 1 micron sediment filter - whole house. And have a combination carbon block and KDF filter for the kitchen sink and icemaker fridge. Rainwater has a naturally very low mineral content. Meaning I like the taste, and a side benefit is that soap bubbles up more.

As for that skywater unit - it didn't say if the 4.2kW power consumption was a continuous draw. Or if they meant 4.2kW/hr per day. If that is continuous - it is just over 100 units per day - crazy high power consumption. Even if it is 4.2kW/hr per day. You will still need a really large off grid system to provide for that demand. I can't possibly see how a skywater unit could ever be sensible. Especially from an environmental point of view.

Thanks for that. My main 'thing' was all the bad experiences I've had looking at other people's roof water systems across several decades......and what's in the gutters before the water gets to the tank....and the tank is rarely if ever cleaned, concentrating whatever goes into it over time. Lots and lots of bird feces and dead insects and spray drift of all kinds...... I'd pay a lot of money to avoid drinking feces and urine and carrion and fertiliser / pesticides in solution. I'm not sure there is any environmental impact of an AWG driven by renewable solar (or renewable grid) power is used so you'd have to expand on that. Assume a 348L unit / day model running at even 50% capacity....for 8 hours / day while the sun shines. That's still 60L of water / day for 34kw. More than enough for drinking and cooking. Shower and do the laundry with the roof water after treating it.

But you're right overall. It's expensive. I'm waiting to hear back from them. I suspect they'll see the Kiwi contact details and just not respond. One of the reasons I don't go to live there. That sort of attitude is far too common over in OZ.

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trig42

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Reply # 1642305 29-Sep-2016 08:59

Surely you can filter and purify rain-water more efficiently than condensing it out of the air?

UV and Micro-filtration should be enough to rid your water of most everything. After that you could boil it if you are really paranoid (or, bleach it).

Our holiday home (up the very top of the Coromandel - near Fantail Bay) gets water from a stream. Has done for as long as I can remember. We boil after heavy rain, but generally don't bother otherwise (unless for babies/sick people). I live on Waiheke - have drunk tank water collected from the roof all my life.

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Reply # 1642455 29-Sep-2016 10:59

Linuxluver:

Lots and lots of bird feces and dead insects and spray drift of all kinds...... I'd pay a lot of money to avoid drinking feces and urine and carrion and fertiliser / pesticides in solution. I'm not sure there is any environmental impact of an AWG driven by renewable solar (or renewable grid) power is used so you'd have to expand on that.

While condensing water out of air will exclude bird feces and dead insects, I think you'll still get spray drift.

I suspect that the concept of a solar-powered AWG is a bit self-limiting in NZ. When there's lots of solar power, humidity will be low so you won't get much water out of the air. Conversely, when humidity is high, it's likely to be overcast or raining, without much solar power available. In tropical climes where it's likely to be 99% humidity whilst the sun is shining, it could be a lot more effective.

I think the environmental impact would be the amount of land you would use, and the resources that go into setting up the AWG. For example, How much energy is used to manufacture the device, deliver it, erect it, maintain it for its lifetime, and how much energy would be needed to get the same amount of equally good water by other means? Another environmental impact, depending on how efficient it was, could be that your neighbours downwind might not be able to set the same thing up, or might find their gardens were drying out.

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Reply # 1642697 29-Sep-2016 15:09

Now that is really overboard!

Firstly condensate is by definition pure water, and secondly, 60L/day will do NOTHING to the general level of the air content, even if every person in the whole country did this...

Directly from the FAQ of the original link:

What is air-to-water technology?
Air-to-water technology is the process of converting water vapor in the air (humidity) to water. replicates this natural process of condensation by simulating the dew point, which allows it to make water continuously, even in low humidity conditions.

How much water is in the atmosphere? Is air vapor an unlimited resource?
There’s approximately 3100 cubic miles (mi3) or 12,900 cubic kilometers (km3) of water in the atmosphere. That’s almost enough water to fill all the Great Lakes of the United States. Water vapor is an unlimited resource constantly replenished by nature’s hydrologic cycle so extracting water from air can continue indefinitely without impacting the planet.

In NZ, we are surrounded by ocean, even if we were able to effect a change to the average humidity of the country, the ocean would be replenishing it on a continual basis, turning salt water into clean is exactly what the water cycle does, and the reason life on earth is possible.

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Reply # 1642715 29-Sep-2016 15:23

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I am thinking you could build a purpose-built rain collector that only operated when it rained (with a rain sensor and powered sealed covered roof) , for a truckload less than condensing water out of the air.

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