Wind Turbine Extracts Water From Air

An anonymous reader writes "Getting access to enough water to drink in a desert environment is a pretty tough proposition, but Eole Water may have solved the problem. It has created a wind turbine that can extract up to 1,000 liters of water per day from the air. All it requires is a 15mph wind to generate the 30kW's of power required for the process to happen. The end result is a tank full of purified water ready to drink at the base of each turbine."

Comments

Windtrap

[MrEricSir]

Finally, we've developed the technology to colonize Arrakis!

Re:Windtrap

[Anonymous Coward]

I was just talking to my uncle Owen about the condensers on the south ridge. If I don't get them repaired by mid-day there will be hell to pay. Life is hard on a moisture farm.

Re:Windtrap

[interkin3tic]

Wasn't the air so devoid of moisture there that you needed a breathing apparatus to not dessicate that way?

Which brings me to a serious point: does that "up to 1000 liters of water per day" mean "If you put it right next to a lake with a really strong wind and the humidity is 99%"? The yield must depend on moisture. Is this going to be useful in the Sahara or just outside of Las Vegas?

Re:Windtrap

[IcyHando'Death]

The yield must depend on moisture. Is this going to be useful in the Sahara or just outside of Las Vegas?

From TFA:

A prototype unit was constructed and erected in Abu Dhabi 6 months ago and has consistently produced up to 800 liters of water a day.

There's that "up to" again. This is marketing speak. I make a point of mentally translating it to "never, under any circumstances, more than", or "between 0 and". Anybody who intends to give helpful information gives an average and possibly standard deviation, including whatever conditions needed to attain those figures. If your only intent is to promote your tech, you say "up to".

On another note, this is not likely to be used to provide drinking water where seawater or ground water high in salts is available. You'd get more bang for your wind power with desalination. On the other hand it could be very useful for drip irrigation, where salts remaining in desalinated water and even relatively good ground water present long term problems for agriculture as they accumulate over time to concentrations that no crops can tollerate.

Re:Windtrap

[trout007]

Holy crap my experience as an ME comes in handy on /.

You are correct. You have to use energy to cool the air and the water in the air. But it's much easier to cool a mass of dry air than wet air. But you get less water out of dry air. You have to think of the air being cooled as wasted energy although some can be recovered by using the cool dry air to pre-cool the incoming moister air.. Also you have to cool the air to below it's dew point in order to get the water to condense. In dry air you have to cool it much further to get to the Dew Point.

Take a look at this psych chart. http://www.rfcafe.com/references/general/images/psychrom_chrt.gif

This tells you how much energy it takes to cool air from different states.
So lets take air at Death Valley. Right now it's about 70 F and 20% Humidity.
Looking on the chart you have:
Enthalpy 20 BTU/lb
Dew Point 30 F
1 lb of air you have 25 grains (.004 lb) of water

Take Orlando. Right now 80 F and 50% Humidity.
Looking on the chart you have:
Enthalpy 30 BTU/lb of air
Dew Point 60 F.
1 lb of air you have 80 grains (.011 lb) of water

So the air in Orlando contains 3 times as much water per lb of air.
The energy required to cool it is 1.5 times as much per lb
You only have to cool 50% of the temperature difference (80-60) = 20 F vs (70-30) = 40 F.

Now lets say you want to get 1000 liters = 2200 lb of water out of the air. Assume you will be able to reduce both to a humidity ratio of 10 grain/lb.
For Death Valley you will get 15 grain/lb of air so you need to cool 1,026,666 lbs of air.
Look on the chart for the before and after enthalpy and you get (20-5) Btu/lb = 15 BTU/lb
You need about 15 x 10^6 BTU to make 1000 liters.

For Orlando you will get 70 grain/lb of air so you need to cool 220,000 lbs of air
Look on the chart for the before and after enthalpy and you get (30-5) Btu/lb = 25 BTU/lb
You need about 5.5 x 10^6 BTU to make 1000 liters.

see also

[Trepidity]

A Slashdot story from 2009 on the same idea. That one wasn't operational at the time, though (except as a research prototype), and this seems to be from a different group.

Re:see also

[Anonymous Coward]

I had the same question and did a little Googling. Using some huge assumptions:
* Wind turbine complexes cost about $1.2 - $2.5 M per MW nameplate capacity. Use the high end of that range because we lose some efficiency of scale, adjust to 30kW and we have about $75K for the turbine.
* They say the Abu Dhabi has been producing 800 L / day, and the nameplate production from the spec sheet is 550 - 1200 L / day. Let's go with 800 L / day consistently on the low-ish end.
* No clue on maintenance costs or lifespan, but lets give it 10 years

$75,000 / (800 L / day) / (365 * 10) = $0.025 / L

Municipal water rates vary all over the board, but they're generally between $0.30 and $3.00 / CCF (100 cubic feet). This is about $0.0001 to $0.001 / L, or 25 - 250 times cheaper than this unit

New problems

[glittermage]

Now the birds will get dry eyes.

Yes, but ...

[philarete]

Will you need a droid that understands the binary language of moisture vaporators?

This would also be useful on tropical islands...

[Andy Dodd]

Smaller tropical islands are very humid but often don't have enough rainfall to keep an adequate freshwater supply, and as a result use desalination plants.

A turbine like this would work quite well in such an environment.

Re:"up to 1,000 liters of water per day"?

[mcrbids]

Many deserts are also relatively humid.

Remember that deserts are defined by precipitation, not humidity. Deserts next to coastal areas lacking sufficient mountains to extract the humidity (such as Abu Dabi, referenced in TFA) are prime candidates.

This wouldn't work nearly as well in, say, Phoenix Arizona which is not only a desert, but is also arid and dry in every sense of the word.

Re:This would also be useful on tropical islands..

[mlts]

This would also be useful for areas such as rural parts of central Texas, where the water table is so low that drilling a reliable well is dicey, the humidity is high, and the wind is fairly constant for most of the year.

For a small farm that tries to be as off-grid as possible, other than the noise factor from windmills, this would be ideal. If the water yield is good enough, it would mean irrigation is taken care of regardless of drought conditions.

I just hope this technology doesn't just fade away as many others have in the past. There is definitely a use for this around the world, as usable fresh water becomes harder and harder to find.

Re:Moisture Vaporators!

[NonUniqueNickname]

As far C-3PO knows, the binary load lifters story is true. Shortly after the conclusion of Episode III, C-3PO contracted the Tyrell Corporation to wipe its memory banks and implant the memories of another robot. C-3PO effectively has no recollection of Episodes I, II, or III. Lucky bastard.