Wind Turbine Makes 1,000 Liters Of Clean Water A Day In The Desert | Hacker News Reader

Wind Turbine Makes 1,000 Liters Of Clean Water A Day In The Desert

treehugger.com

108 pointsph0rque46 comments

"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?

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.

> 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.

> 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.

I gave up trying to correct treehugger after they featured the concept shower that would be heated from electricity generated from piezos capturing vibration from the flow of water pumped through the pipes.

It seems they are quoting an article from rechargenews.com [1] which erroneously adds this "steam before condensation" stage.

Reading the skimpy tech specs of the "WMS1000 Wind Turbine" from the company itself [2], it only lists the following stages:

Energy production -> Ambient air suction -> Humid air condensation -> Water production -> Water purification -> Pure drinking water distribution

----

Ensuring the water is airborne pathogen free would be a big issue for me which I am sure they must have thought of.

"Eole chief executive Marc Parent dreamed up the concept in the 1990s while working as an engineer in the Caribbean, where he had been reducing his bottled water costs by siphoning the condensation from his air conditioner."

I hope he boiled this water here first. This is the exact method used by new airborne pathogen detectors to collect virus and bacteria samples :/

[1]: http://www.rechargenews.com/business_area/innovation/article...

[2]: http://www.eolewater.com/gb/our-products/range.html

I think that this is just a generator driving a standard de-humidifier. The compressor is compressing -refrigerant-, not the air. The refrigerant expands into a cooling coil, which chills the air and condenses out any moisture.

This is just like the dehumidifier that you use in your basement, only out in the desert somewhere and attached to a wind turbine. I'm not sure why you would do this instead of just capturing the power. Perhaps because if you're installing this in the desert, power transmission could be difficult, whereas the water could be collected in a holding tank at the base and used locally?

The author got this TOTALLY wrong.

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.

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.

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

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...

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

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.

Nice, and I thought this was good: http://www.bbc.co.uk/learningzone/clips/living-without-water...

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?

What if you combined these: http://sizedoesntmatter.com/wp-content/uploads/Picture-92.pn... 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.

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

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

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.

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.

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

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.

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

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.

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.

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.

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

I think drinking it and growing food might be more of a direct application.

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.

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?

Water desalinization plants run over $4 billion easily. They do about 200 gigalitres per year.

Of course these things will get cheaper, and you don't need to pay $4 billion, you can set up smaller numbers of them.

I think your numbers are off. 200 gigalitres would provide for 27 million people at 20 litres per day.

If that plant can last 30 years as well, discounting any maintenance, that's $4.8/person/year.

And, tangentially, desalination plants need salt water, so only works near the coast. The wind-turbine would work anywhere, regardless of the distance to the coast.

If you have 27 million people in a catchment area, they are going to be using far more than 20 litres per day per person.

Melbourne is a non-desert city in a Western, water-conscious country, that in 2008 was nearing the end of a 10-year drought with water reserves starting to approach the 'panic' levels. The city was on ever-tightening water restrictions and water consciousness was pretty much part of daily conversation. In the end, three and a half million people were using 277 litres per day per capita. What you've forgotten is that many people need industry, and industry needs a lot of water.

http://www.melbournewater.com.au/content/water_conservation/...

277L per day per capita is quite impressive. I lived in Santa Fe, NM which is a near-desert city in the US with a small catchment area and at 2000m+ elevation. In 2010 they used 400L per day per capita.

I've been trying to find comparisons for other cities. I came across http://www.circleofblue.org/waternews/2010/world/the-price-o... which shows just how hard a comparison that is.

That is, it shows that Boston and Milwaukee use less water per capita than Santa Fe. They get more rain so there's probably less use of water for outdoor use. Boston only used 150 L per day per capita?

That's still a lot more than 20L/d/c.

Boston's use is remarkably low. I think it's over half of Melbourne's use is industry, so I'd take a wild stab that Boston gets an unusually large part of its wealth from services rather than industry, which would use much less water. That's just guesswork, though.

A curious anecdote - in Melbourne in the '50s and '60s, it was actually against the law to have a private water tank, and this wasn't changed until the '90s, from memory. My mother installed an illegal water tank in the late '80s. It sounds crazy now, but Back In The Day, water tanks weren't well sealed, and Melbourne had a massive mosquito problem. Fast forward a few decades, mosquitos are no longer a problem but drought is, so now you get incentives to install tanks...

Ah, found the difference. That 150 liters/day for Boston is classified as 'residential use', whereas the Melbourne figure is for all uses. The Boston figure doesn't include industrial use.

Well done!

I had assumed that that comparison graph used the same measure for all cities. Its Santa Fe value matches that described in http://www.santafenm.gov/index.aspx?NID=168 : "The City of Santa Fe computes its per capita water use as the daily average of annual total water diversions from all sources of supply, less bulk water deliveries to the County of Santa Fe and Las Campanas, divided by the estimated customer population served." That's what you were using for Melbourne, but it seems that that's not what the Boston plot was using.

But Santa Fe has little in the way of industry. "Of the 8,500 acre-feet billed, the single family residential sector used 4,530 acre-feet (53%), the multifamily sector used 878 acre-feet (10%), and the commercial sector used 2,743 acre-feet (32%). Irrigation use accounted for 330 acre-feet (4%)."

At 5408 acre-feet per year, with a service population of 80,000 people, that's about 230 liters per day of residential use per person, which is still more than Boston's residential use. I think that's attributable to how Boston gets much more rain; 41.5"/1050mm vs. Santa Fe's 13.8"/350mm.

How much rain did Melbourne get during those 10 drought years? It looks like around 650mm, so you can see how Melbourne is a somewhat wetter place than Santa Fe. Santa Fe encourages rain barrels, and I can understand how they would also be effective in Melbourne.

(I also don't know how private well usage affects these numbers.)

(Edit: Ooops! Mixed up Melbourne and Sydney - now corrected.)

Yes, 27 million people in dystopian poverty, or about 1 million average (mean) residents of this rich petrostate. [1]

Getting to the point on costs: it's supposed to be around $2/m^3 in the UAE for desalination, so ~$400/capita/year. It would be around $15/capita/year at 20 L/year, but that kind of consumption wouldn't logically exist side-by-side with billion-dollar desalination plants (if your society is developed enough to have built things like that, it's probably wealthy enough not to be counting fractions-of-a-cent aka. liters of tap water.)

[1] http://www.thenational.ae/news/uae-news/thousands-of-abu-dha...

[2] http://www.zawya.com/story/ZAWYA20100808044642/UAE%20Spends%...

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%...

[2] http://gulfnews.com/news/gulf/uae/general/dubai-introduces-n...

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

[4] http://www.thenational.ae/news/uae-news/thousands-of-abu-dha...

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.

The article says the turbines are 30kW, not 300kW.

Sorry, I was unconsciously adding context not directly in the article.

One of the articles linked to[1] indicates that this article's statements are misleading. The turbine is "the size of a standard 300-500kW model", but generates 30kW of excess capacity used for pumping and purification.

[1] http://www.rechargenews.com/business_area/innovation/article...

I'm assuming it would be cheaper than a power turbine, since it won't need all the infrastructure for power transmission, would it? Although I guess it would need the equivalent of water transmission.

To my knowledge, the cost I mentioned is for just a turbine/generator unit. It's what you'd pay if you could walk down to a Home Depot and, well, "pick one up". Any transmission infrastructure is an additional cost.

This would obviously need a holding tank of some sort, but in the areas water is really scarce in practice, people don't so much care about getting it delivered to their home. This could be the equivalent of going to a well or stream to fill some containers.

Can they be subsidized by government? E.G. is one of these cheaper to set up in remote places (assuming that the cost numbers are correct and don't change downward) than the cost of:

"efficient desalinization" + building pipelines + building pumping stations + maintenence on infrastructure

for 30 years?

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.

Reply on news.ycombinator.com