

Wind Turbine Makes 1,000 Liters Of Clean Water A Day In The Desert - ph0rque
http://www.treehugger.com/wind-technology/wind-turbine-makes-clean-water-desert.html

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ars
"Air is taken in through vents in the nose cone of the turbine and then heated
by a generator to make steam. The steam goes through a cooling compressor that
creates moisture which is then condensed and collected."

Um what?? Why are they heating air? And you don't make steam if you heat air.

That's either a huge typo, or whoever wrote that has no idea what they are
talking about. Maybe they tried to summarize the source without understanding
it?

You could either cool the air to condense the water, or compress the air,
which heats it temporarily, then you cool it back down and collect the water.
It's ideal to recover the energy either way though and this process doesn't
seem to do that.

And in any case what does this have to do with a wind turbine? This is
basically a de-humidifyer. You can power those with anything - wind,
electricity, gasoline.

I suggest they use the wind turbine to make electricity, and then power the
de-humidifyer from that. That way you can pick and choose what you want to
power, and you can power the de-humidifyer from something else when necessary.

BTW the link they have on the words "simple process" in fact has nothing
whatsoever to do with this process. Who writes this stuff? Someone who never
learned any science?

~~~
electromagnetic
Forget the stupid writing in the article. The reason why they may be using the
wind turbine directly is if they're using mechanical energy to fire the
compressors, etc to run the process.

Compression of the intake air is likely best served mechanically. Cooling the
air could be served mechanically, although an air conditioning compressor is
likely better designed to run electrically, but again it depends on the scale
used to determine if mechanical would be better or not.

Although I'm wondering if the compressed air itself could be used to power the
condenser. If the air is compressed enough, would an appropriate design allow
the expansion of the compressed air to cool the condenser it's escaping from?
Because I know air compressors for air tools build up water inside, and they
are purposefully designed to inhibit this.

Also the reverse-osmosis, or whatever filtration used, is likely best served
by producing the water and letting it filter down through gravity pressure
under the 30+ft drop from the unit to the holding tank.

Although, it would be more ideal to produce say 200L a day and produce energy
too so that a few of these would provide water and electricity to a village
and everyone won't die when their water producing turbine breaks down and
takes a month to get repaired.

~~~
ars
> The reason why they may be using the wind turbine directly is if they're
> using mechanical energy to fire the compressors, etc to run the process.

The gearing would make this too complicated. A compressor wants a constant
force, with a varying speed. But a turbine produces a varying force. (This can
be adjusted somewhat by angling the blades, but not enough.) Older turbines
run at a constant speed, the extra force allows more electricity to be
generated. Newer ones are more complicated running at varying speeds. But in
both cases the force varies, which would not work for a compressor.

You don't need to both compress the air, and refrigerate it - it's either/or.

If you compress the air, the cooling is just ambient cooling. A way to capture
that energy is pretty important. It would be easy to capture the energy in the
compression of the air, but once you cool it the pressure drops which is a
waste. Maybe dump the heat after the expansion to increase the pressure of the
air before using it?

The gearing of this system would be pretty complicated - you have energy from
the turbine, then energy from the compressed air releasing. I guess a
differential gear would work.

Refrigeration is a lot simpler in some ways (after condensing the water, use
the cold to help cool the hot side) but designing a refrigeration pump to run
at varying speed is really hard. And varying force is no good either.

You don't need reverse osmosis for the filtration - the water is quite clean,
it just has some dust in it which a simple filter could handle. May be easier
to filter the air instead.

~~~
electromagnetic
> You don't need reverse osmosis for the filtration - the water is quite
> clean, it just has some dust in it which a simple filter could handle. May
> be easier to filter the air instead.

I was thinking the same when I read the article. I assumed they didn't intend
to filter the air because an air filter may become clogged by sand particulate
- especially in a sand storm. I said reverse osmosis for the filter, merely
because this setup is actually well suited for it, and if these turn out to be
mass produced (hopefully cheaper for more litres of water a day) that they may
become used in more urban areas where pollution is a bigger factor. It would
also make bacterial contamination less of a concern as mild chlorination of
the holding tanks would likely make a long term potable water source with low
maintenance.

However, the advantage of compressing over refrigerating is that the
compressed air could be vented to periodically clean any air filters. It's
important that these turbines be very low maintenance if they're to be
installed in remote areas. A self-cleaning air filter _and_ a simple water
filter might be ideal.

------
drostie
I had this idea in high school! I thought it wouldn't work in the desert
though, or surely it would already have been tried.

Basically, we were reading about just how difficult it is to get water out of
saltwater in coastal communities, and the massive power costs involved, and I
just thought, "well, we sometimes have to use a dehumidifier at home, and I
know that that runs on the mains power and could generate easily enough water
for two or three of us to survive. Coastal environments have very wet air, so
just let the Sun act on the ocean to do the hard part of desalination, and we
reap the benefits of clean water?"

I gave up because I'd calculated that this would also probably cost more money
than poor coastal areas had, but yeah, wind turbines have grown amazingly in
the past several years and the principle is pretty sound. (It is not clear
what the longer-term environmental impact would be, but it's possible that if
we deploy too many of these things, inland droughts could become more severe
due to lack of cloud formation.)

I'm glad to see that someone has paired renewable energy and automatic solar
evaporation with the problem of desalination. Well worth some charity money,
though the company as it stands appears to be for-profit. Would be nice to see
if a charity could set some of these up in Wajir, Kenya, as a politically
safer experiment towards deploying them into the drought-ridden Jubaland in
Somalia.

~~~
brlewis
You were probably not the first with this idea:
<http://en.wikipedia.org/wiki/Tatooine#Moisture_farms>

I'm surprised this article has been on HN for 10 hours already without any
Star Wars references.

~~~
rthomas6
Star Wars stole the idea from the Dune series, actually, so the idea is even
older than that.

------
uvdiv
There's a slight disconnect between the PR and spec sheet, which predicts an
output of 1,000 L/day in a "temperate zone" (60% relative humidity, 25 ºC), or
350 L/day in a "desert zone" (30% r.h., 35 ºC).

[http://www.eolewater.com/assets/files/PDF/Specification%20Sh...](http://www.eolewater.com/assets/files/PDF/Specification%20Sheet%20WMS1000%20WT%20light.pdf)

~~~
uvdiv
Another observation from the datasheet: this seems extremely energy-intensive,
even compared to desalination. Modern desalination ranges from about 3
kWh/meter^3 (reverse osmosis) to 13-25 kWh/meter^3 (multistage flash
distillation) [1] [electricity-equivalent kWh]. The wind turbine's spec sheet
says it has two scroll-compressors rated 30 kW combined. I'm not sure about
the capacity factor these compressors operate at (no data given), but _if_
it's basically that of the wind turbine itself (should be about ~20%), that's
~140 kWh (mechanical energy)/day for 1 meter^3/day water, or 140 kWh per m^3.
Triple that for a desert zone (same energy, one-third the output).

[1] <http://www.desware.net/desa4.aspx>

------
ams6110
This is a better use of wind power than generating electricity for the grid.
Since the wind doesn't always blow, use wind power for systems where it's easy
to store the product. Storing water is easy. Storing electricity is not.

------
downx3
Nice, and I thought this was good:
[http://www.bbc.co.uk/learningzone/clips/living-without-
water...](http://www.bbc.co.uk/learningzone/clips/living-without-water-
atacama-fog-catching-nets/11949.html)

------
outworlder
I went to the article expecting a "windtrap" design. I came here expecting a
"Dune" reference. Got disappointed on both counts.

Anyway, shouldn't this thing use a bigger collection area?

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creativeone
What if you combined these: [http://sizedoesntmatter.com/wp-
content/uploads/Picture-92.pn...](http://sizedoesntmatter.com/wp-
content/uploads/Picture-92.png) with the wind turbines? Free heated water...
Am i missing something?

If this is possible i will be the first proud salesperson of this in Israel.

~~~
downx3
I doubt you'd care for hot water in the dessert. You could just fill a black
bag. Cool clean water is probably preferential.

~~~
chris_wot
It gets pretty cold at nightime I've been told...

~~~
downx3
You could use solar water heating as a vector to trap the suns heat in an
underground heat store, that you then release at night. How cold does it get?

Edit:

I just tried to find out about night time temperatures. On the wikipedia page
'desert', it suggests it only gets as cold as 0 degrees C. Although I did find
a remark that Antarctica was technically a desert.

I just camped out in temperatures below 0 weekend gone, and it wasn't that
comfortable, but I was staying under a thin piece of plastic. If I'd have been
a bit better prepared it would have been much more bearable.

~~~
dalke
There are hot deserts and cold deserts. The Gobi has a yearly average
temperature of 2.8 °C, with a January average of −26.5 °C and July of 17.5 °C
. Red Desert, Wyoming averages -7°C in January.

My relatives in Michigan mentioned that there's a Polar Bear scouting award
for camping when it's below 0°F, or -18°C. My own sleeping bag is only rated
for -2°C.

~~~
downx3
I must add then that it was just below 0 degrees C! Don't fancy minus eighteen
at all.

------
sparknlaunch12
Great story.

Check out a recent podcast from Stanford e corner. Jeff Church - The Wave of
Social Entrepreneurship.

He talks about encouraging startups to look at social causes. His own Nika
bottled water give their profits towards clean water.

Positive way to go about building your startup.

------
pingou
Is this water a virtually unlimited resource or can it dry up if these
turbines are implemented on a large scale ?

~~~
rmccue
It uses the humidity in the air, so it's possible that with a larger number of
these in the area, the humidity would be reduced to a point where there is
none left to remove.

~~~
ars
Nah, there's wind, and the ocean. Less humid air evaporates ocean water
quicker, and the wind will circulate the air till it eventually reaches the
ocean.

The Earth is enormous, it would take a staggering number of these to make any
dent in humidity, and even then it would be a local dent only.

Don't forget water is a closed loop - this water they consume is also
eventually returned to the environment (sweat, etc.), where it evaporates and
restores the humidity.

~~~
downx3
I like the idea of taking the water back out the sea and placing it in
underground aquifers. Some are are seriously depleted through industrial
agricultural farming.

Would be nice if you could just pull a cloud or two down from the sky.

------
Egregore
Next step will be to transform the condensed water into hydrogen for energy
storage.

~~~
ars
No, that is not the next step. That is a silly step.

You need a lot more water as water than you do as hydrogen. For hydrogen sea
water is more reasonable, and transporting it isn't a problem since you don't
need much.

In any case, hydrogen can not be energy storage since it leaks too easily. It
also damages any metal container it's stored in (and leaks right though
plastic). Glass might work.

------
nknight
Yeeeah, that's a heck of a lot of water in a desert. I'm a bit worried about
the cost, though.

They don't mention per-unit cost anywhere, but they're comparing its size to
300-500kW turbines. If memory serves, those are a few hundred thousand a
piece? So maybe we can assume these will be ~$300k...?

Supposedly, minimum health and sanitation is 20 litres per person per day.
Assuming these last the 30 years stated on Eole's website, and consistently
output 1000 litres/day, and not counting any maintenance costs,
$200/person/year.

Can the areas that need these things the most afford $200/person/year?

~~~
uvdiv
Try per unit of water, so you can make meaningful comparisons. Desalinated
water apparently costs/is priced at USD $2-3/meter^3 in the UAE [1,2] (0.2-0.3
cents/liter), so 1,000 liters/day => $2-3/day or ~$1,000/year.

A large UAE desalination plant for comparison [3]: natural-gas fired CCGT
piped to an offshore gas field, 1,430 MW electricity, and 380 million liters
desalinated water/day (~$1 million/day or ~$300 million/year), presumably from
waste heat.

Average per-capita water consumption in the UAE is 550 liters/day [4] (so
~$400-$600/year?) -- actually among the highest in the world, comparable to
the US. The point probably being that their GDP/per capita is also comparable
to the US, so the desalination cost isn't that big of a disincentive.

[1]
[http://www.zawya.com/story/ZAWYA20100808044642/UAE%20Spends%...](http://www.zawya.com/story/ZAWYA20100808044642/UAE%20Spends%20Dh11.8%20Billion%20On%20Desalination/)

[2] [http://gulfnews.com/news/gulf/uae/general/dubai-
introduces-n...](http://gulfnews.com/news/gulf/uae/general/dubai-introduces-
new-rates-to-curb-use-of-electricity-and-water-1.85172)

[3] <http://www.power-technology.com/projects/taweelah/>

[4] [http://www.thenational.ae/news/uae-news/thousands-of-abu-
dha...](http://www.thenational.ae/news/uae-news/thousands-of-abu-dhabi-
buildings-face-cuts-in-water-usage)

~~~
nknight
As you notice, the UAE is rather wealthy. I seriously doubt they located the
prototype near Abu Dhabi because it was a location in dire need of safe water,
rather than convenience and publicity.

A few other middle eastern, and numerous African countries, with GDPs so small
you'll think there was a typo, both desert and not, have serious clean water
shortages.

------
ktizo
That is an exceptionally good idea. As far as green tech goes, I reckon a load
of these combined with polytunnel aquaculture could be on a par with the
seawater greenhouse, it would probably produce less water per hectare but then
it doesn't need the big pipe to the sea - <http://www.seawatergreenhouse.com>
\- would be interesting to see a proper comparison.

