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Air Well - collecting water from the air  RSS feed

 
Posts: 656
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Jeff Jefferson wrote:
paul wheaton wrote:From Jack's link:



I think this is a great idea. I am tempted to call this a "johnson style air well"


Thats a genius Idea, I would really like to stack that with a solar chimney.


It seems like it would be difficult to dissipate the heat accumulated in this air well design. For example, about the same amount of energy is released into the soil when 1 gallon of water is condensed is about the same as when the air in a 1000 square foot house is cooled by 55 degrees Ferinheight. Typical geothermal heat pumps use hundreds of feet of coil to dispense the heat, but this system looks to be limited to a fairly short pipe with a pretty steep slope.
 
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Hi
I saw a plan like the jefferson airwell that involved 100 feet of underground pipe. While i'm interested in the idea, i'm not interested in digging the trench by hand.

A thought, in the NE arizona desert i wanted an outside tub so that i could cool off every once in a while. I dug a tub about 18 to 24 inches deep and filled it with water, (lined with plastic) My keester only touched that water once and i decided it would be a standing tub. I didn't take it's temperature but the water picked up a lot of cold, in june.

I'm thinking of that 100 foot of black pipe ($62.00 at home depot) heating up in the sun and the warm air being drawn into contact with a small in ground water pond.
Like an Arizona dew pond.



 
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So, here is a question for you guys.

I have a part on my property, right close to the house, where it has a semi-steep drop-off about 30 feet, and right below it is a long "shelf" of about 2 acres of pretty flat land before it slopes off down the mountain again.

I want to someday plant sugar maples there, but I'm not really hot on setting up a traditional watering system... so I've been sorta thinking about a passive way to water these trees or keep them moist enough.

This system that we're talking about - I wonder if I could install a few of them along the ridgeline, and instead of some reservoir, to just allow gravity to feed the water down into pipes that then come out in the drop-off and ultimately go directly into irrigation lines? Does that make sense? So it would be kinda like a constant passive irrigation.

I know I will be doing some kind of really awesome mulch and have been thinking about stacking rocks around the trees, along with digging out some kind of dish to plant the trees in so that rainfall would collect around them... but this might be a good solution. Probably wouldn't be too expensive to set up, too, at least the underground part so you can see if it would work or not.
 
gardener
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Location? Climate? Temperature zone? Ground water?
 
Bethany Dutch
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Rebecca Norman wrote:Location? Climate? Temperature zone? Ground water?

lol! Sorry

Spokane-ish, Washington State
zone 5b
yes on the ground water, though none running that I know of in the particular spot I'd be putting it in.
Winter lows generally get in single digits but now below 0 Fahrenheit, and our hottest summer temps are usually around 105 for maybe a week in midsummer. Normal winter lows are around 20 and summer highs around 95.
Average relative humidity in non-frozen months goes from 75.0 in March to 45.5 in August before it starts to climb again before winter.

Definitely not a dry climate, and I know I could get this to work, just not sure about the whole passive irrigation of trees thing. I may draw a diagram to show it better. I can't see why it would NOT work, but then again I'm not an expert at these things. One thing that might be an issue is that if the water is a slow trickle, how would I ensure that each tree was receiving an appropriate amount of said trickle into it's irrigation pipe? if I can get this to work it would make a huge difference for me down the line when I put these in, since one of my biggest obstacles is the amount of labor and time to irrigate so many trees. I have at least a half a mile of this bluff that I could use.

COme to think of it, my vegetable garden borders on a steep hill as well, in a different place.
 
Rebecca Norman
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I don't know anything about the west coast, but if you say it's not a dry climate, and the temperatures you mention sound similar to New England, so maybe sugar maples would grow well with no irrigation. Do you see them growing in the area? Whether they will produce much sugar is a different question -- supposedly in some places, sugar maples grow fine, but don't produce much sap for collection because of the springtime conditions.
 
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paul wheaton wrote:From Jack's link:



I think this is a great idea. I am tempted to call this a "johnson style air well"


This is a really simple and scalable idea for an air well! I can see how you can adapt it in different ways already.


Has anyone ever thought of using zeer pots in an air well system? (here's a link if you need info: http://rebuildingcivilization.com/content/busting-myths-about-zeer-pot
)

They're basically passive refrigerators that use water to cool. I can totally see how they can be part of an air well system though.
 
master steward
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Jocelyn Campbell wrote:Here's a new, sculptural air well design. Just one photo here. Go to A Giant Basket That Uses Condensation to Gather Drinking Water to click through the entire slideshow.



It looks like they have updated the design:





https://www.kickstarter.com/projects/366225655/warka-water-each-drop-counts
 
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Does the Warka water design work well? Saw that awhile ago and found it intriguing. Many people want to desalinate seawater when mother nature does it every second by evaporating the oceans and raining on land, keeping the balance of moisture in the air as well.
 
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Just found this thread and it's prompted me to rekindle some ideas I have had in mind for a while.

Firstly want to say that there is no point warming up the air before you condense it. Yes while warmer air has more capacity to carry water, that only matters when it's picking up water, eg when its coming over the sea. Once you're about to condense the water vapour you want to cool it. If you heat it, the amount of water in the air will stay the same, but its relative humidity will decrease, and you will require more energy to cool it. Here's my earliest idea on how to condense water out the air.

Have an enclosed sump/tank of water, enclosed to stop evaporation, and must be in a cool location so possibly underground but at very least in the shade.
Have a connected shallow pond, say 1 cm deep, but with a large surface area. Should also be in the shade but must be exposed to ambient air.
Have the ambient air monitored for humidity and temperature as it comes across the shallow pond.
If the temp of the water in the sump is below the dew point of the ambient air, the pond is filled by pumping from the sump.
If the temp of the water in the pond rises to the same as or above the dew point, it is pumped back into the sump.
So we have a dew pond that is full when it would collect water, and evacuated when it would evaporate. As long as there is no significant change of height between the two then pumping would be very cheap and quick, could be run from a small solar panel.

 
Steve Farmer
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And my next idea...

Instead of trying to take ambient air and cool it to condense the water, in the hot climates we're talking about, we find it easier to heat stuff up than to cool stuff down. EG some black poly pipe in the sun can get up to 50C fairly quickly when ambient temp is 20C. But try to come up with a way of cooling it anything like 30C. By using a desiccant, you can take water out of the air at ambient temp, ie no cooling required. Then your challenge is to recharge the desiccant, which you do by heating it. Once the desiccant is heated it gives up its moisture, ideally in an enclosed area where you can capture that moisture perhaps something resembling a solar still. OK you do have to do some cooling now, you have to cool the desiccant back down again. But you only need to cool it to ambient temp, which requires no energy input, just some sort of heat exchanger like a car radiator maybe.

So my idea would be passing ambient incoming air over the surface of a strong solution of for example calcium chloride. The calcium chloride would adsorb water, becoming a weak solution. This is then pumped thru black poly pipe to a solar still (or a rocket stove if fuel and emissions are less of a consideration than the need for water). In the still the desiccant gives up some of the adsorbed water and becomes a strong solution again, but is now hot. The desiccant passes through a car radiator or some other heat exchanger until it is once again ambient temp, and returns to where it started for another pass around.

Energy input is needed in 3 areas

1) Some sort of fan to blow the incoming moist air into the system. An 80W car radiator fan can move a tremendous volume of air and last for years.
2) Something to pump the desiccant around. A $10 20W pump like used in boats to pump drinking water can pump to a head of 5 metres or so. If the system is more or less at a constant level then that would do the job easy.
3) Something to heat the desiccant to recharge it. As mentioned, black poly pipe in the sun would do this.

Calcium chloride is a good desiccant. Although not the absolute best, it is a food grade substance and is cheap. It is however corrosive so the idea of using a car radiator may have to be rethought. Maybe keep the desiccant in plastic pipes throughout, which pass through a tank containing some other non corrosive coolant which in turn is passed thru the car radiator. Or just pass the desiccant thru a plastic pipe that is coiled in your main underground water storage tank, which you of course already have conveniently built.

I've been meaning to build such a system for several years but the opposing distractions of laziness and work have got in the way. My experiments were limited to putting some CaCl in a plastic tray outside for a couple of hours and then observing the plastic tray to be full of water when I checked on it, then putting a clear plastic sheet on top of that solution in the sun and observing the water quickly condensing on the underside of the clear plastic. I put some water in a plastic poly pipe in the sun and measured the roughly 30C temp increase I was talking about earlier. It might have been 30 mins or it might have been 2 hrs, sorry I don't remember. I really should pick these ideas up again as I've got some desperately dry land with not much growing on it.
 
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really superb. I am building a condenser similar...
condenser.jpg
[Thumbnail for condenser.jpg]
 
garden master
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Steve Farmer wrote:Instead of trying to take ambient air and cool it to condense the water, in the hot climates we're talking about, we find it easier to heat stuff up than to cool stuff down.


I've ran the math for my place... The dew point is usually below freezing. What that means in practice is that I have to take ice out of the atmosphere instead of water... But if I start taking ice out of the atmosphere, then my whole mechanism freezes up. So my schemes for air-wells involve sorption mechanisms. It's really easy around here to heat things up.

We had dew two days this winter. It was a surreal experience for me. So Unusual. So disconcerting. The world was just plain old wrong!
 
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Roots Up
 
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Has anyone had experience / success with the Talus Garland effect (a simple pile of rocks). If so, what ambient humidity is required?
 
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I would be concerned drinking water from a "Johnson style air well" for fear of what might be growing in the moist environment of the long condenser pipe.

Perhaps a better solution might be to bury several hundred feet of PEX tubing for a few hundred bucks (put under pressure before burying!) and circulate a fluid to a condenser coil made of copper pipe, or a double wall heat exchanger, that could be periodically inspected and sanitized.

The air could be collected using a large wind scoop and directed over the condenser coil, using insulated ductwork for long runs to minimize condensation in the ductwork.

If you put the condenser at the bottom of a slope and run the pipe uphill, you wont need any pumps, although it would be more productive with a pump.

Small systems that may warm the earth can be left to run on cool nights and recharge the earth to increase productivity the following day.
 
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Lenn Sisson wrote:Here is an interesting design for an air well that I came across today. It includes a wind turbine to pull the air through the system.



Lenn, you've solved my problem. I'll be building some of these. I just have to figure out whether I can use PVC or if I need to get steel pipe.

 
Shan Renz
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Edit: PVC, definitely.
 
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Shan Renz wrote:Edit: PVC, definitely.

Are you sure? PVC has a much lower temperature exchange with the earth than metal.

If finances allow I'd be tempted to go with copper, there won't be anything nasty growing on those pipes. [Though one could simply run the collected water through a quality filtration system as well.]
 
gardener
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This is something they'll actually be building during the upcoming PDC and Appropriate Technology courses at the Lab this summer - in this dry Montana climate, I'm really anxious to see this design in action and track how well it performs.

Link to PDC course Wiki
 
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These things are very clever, and very cool. And for obtaining liquid water, very useful. In some cases, though, I think they might be a bit overengineered. Mulch essentially functions as a distributed air well system

The loosely piled organic matter shades the soil and keeps it cool. At night, this cool soil quickly cools the mulch, air flows through the gaps and crevices just like in a constructed air well, and dew forms. If there is enough dew to drip it'll actively water the area. If not, it'll provide a layer of high-humidity into the daytime to reduce evaporation and keep the water you've already got in the soil. Water has to evaporate from the mulch before it evaporates from the soil, and dew can daily restock the mulch with a protective buffer of moisture.

Mulch doesn't do too much for obtaining bulk liquid water, so air wells would be useful if you can't drill wells for drinking. Or if you are in a very arid area and need to extract humidity from large amounts of air to get any meaningful quantity.
 
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New to posting here, but I came across a website that seems pretty useful. Thought I would share the knowledge.

Water from the Air


Practical means, to providing plenty of water using ground temperature as the condenser.
 
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Looks like this operates on the same principle:

https://www.indiegogo.com/projects/fontus-the-self-filling-water-bottles#/
 
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Amber Beckerson wrote:This must be where Frank Herbert got the idea for "wind tunnel moisture traps" used by the Fremen in the "Dune" books. I always wondered how possible it was for that to actually work.


These traps would likely utilize the venturi effect to help extract water from the air. A continuously blowing wind would drive air through a venturi where, as the air velocity increases through the venturi's constriction, its pressure and temperature drops, efficiently extracting water from the air. This is the same effect that causes carburetor icing on aircraft engines run at reduced throttle settings.
 
Steve Farmer
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Victor Johanson wrote:Looks like this operates on the same principle:

https://www.indiegogo.com/projects/fontus-the-self-filling-water-bottles#/


A 100W retail peltier dehumidifier system, of which probably millions have been sold will produce 250ml (approx. a quarter of a quart) in 24 hrs
Edit - seems these units are rated at 100W max draw but consume as little as 24W, but not sure if they produce at max capacity when running lower power draw.

I am struggling to understand how the fontus system is projected to produce a few litres a day with its tiny (20W?) solar panel.

I read that initial tests were performed in the inventor's bathroom after having the hot shower running. I wonder if the inventor was collecting water droplets already condensed in the air rather than condensing water vapour in his system.
 
Victor Johanson
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Steve Farmer wrote:
Victor Johanson wrote:Looks like this operates on the same principle:

https://www.indiegogo.com/projects/fontus-the-self-filling-water-bottles#/


A 100W retail peltier dehumidifier system, of which probably millions have been sold will produce 250ml (approx. a quarter of a quart) in 24 hrs
Edit - seems these units are rated at 100W max draw but consume as little as 24W, but not sure if they produce at max capacity when running lower power draw.

I am struggling to understand how the fontus system is projected to produce a few litres a day with its tiny (20W?) solar panel.

I read that initial tests were performed in the inventor's bathroom after having the hot shower running. I wonder if the inventor was collecting water droplets already condensed in the air rather than condensing water vapour in his system.


There are quite a few questionable crowdfunding proposals out there, so skepticism is well advised. I saw one that claims to be an antigravity device of some sort, and another gadget that's supposed to function like fish gill to permit humans to breathe underwater...highly dubious. I'm sticking with rocket stove books and such :-) .
 
pollinator
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Wild speculation here: the problem is the solution--what if in desert climates you used the extra sun you have lying around to heat the air around the air well super hot during the day (say, use a bunch of mirrors, or if you don't have that then something slightly shiny, and make the stone itself extra bright in color to reflect more energy/heat.) Then the day-time stone/day-time air the temperature differential is greater, increasing the condensation effect, yes?.

The effect might not be huge but it's a numbers game. You have say 1/10th the humidity of Ethiopia where these work well (I'm making up a number, I don't know what the actual humidity is) but let's say it's 1/10th, then you maybe increase the efficiency of condensation in proportion to how great a temperature differential you achieve, right?

Maybe you could tweak things a bit more by getting the water to a place where it can't evaporate again?

Also, maybe you can take advantage of just how cold the desert gets at night? (more than in a more humid climate where the humidity itself is acting as as thermal mass flywheel-effect thing, sustaining the heat of the day over night). are there things that can be used to help propel the heat out of the rocks at night to cool them more than they would? a way to set up a thermal air conditioner with flywheel effect--storing up air pressure in the day time from heat and then releasing it slowly over night? compressed air cools when it decompresses--any way to harness this effect? I'm talking within the domain of mechanical energy here only, not using any electricity, hopefully no moving parts.

Also, I didn't see anyone mention the ethiopian one, I forget the name of it but it's made into an art piece, uses mosquito netting or something like it as the condensing element. That seems like a pretty great air well, and got 5 gallons a day if I recall.

 
Steve Farmer
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Joshua Myrvaagnes wrote:what if in desert climates you used the extra sun you have lying around to heat the air around the air well super hot during the day


You would need to heat the air while it was picking up water (eg over the sea) to increase its water holding capacity. Once it's already picked up all the water there's no benefit to heating it, it won't get any more water from anywhere, and you will have to cool it more to get as much condensation.
 
Steve Farmer
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Joshua Myrvaagnes wrote:use a bunch of mirrors, or if you don't have that then something slightly shiny, and make the stone itself extra bright in color to reflect more energy/heat.) Then the day-time stone/day-time air the temperature differential is greater, increasing the condensation effect, yes?.


That's an interesting idea, the air is warm in the day but the rocks are prevented from heating up so when night arrives they end up cooler than if they weren't reflective and condensation potential increases
 
Steve Farmer
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Joshua Myrvaagnes wrote:Also, maybe you can take advantage of just how cold the desert gets at night? ... are there things that can be used to help propel the heat out of the rocks at night to cool them more than they would?



I was thinking about the relative coolness of the deep (or even not so deep) ground below the desert. What about steel re-bar into the ground to help dissipate the heat from the above ground condensation surface, the same as your metal heatsink on your computer CPU helps the heat dissipate faster. I think it would be more efficient to insert thin metal rods with high conductivity into the ground than to excavate and install a tunnel for a wider airpipe made of relatively unconductive plastic.
 
Steve Farmer
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Joshua Myrvaagnes wrote:Also, I didn't see anyone mention the ethiopian one, I forget the name of it but it's made into an art piece, uses mosquito netting or something like it as the condensing element. That seems like a pretty great air well, and got 5 gallons a day if I recall.



I've read about these and seen pictures and seen the fundraiser and seen mock ups installed as art but I've never heard of one actually being made or any figures representing results of a test or mock up. Its design seems to be more akin to a fog catcher - which catches droplets of already condensed water rather than actually condensing water from unsaturated air.
 
Shan Renz
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I'm about to build an air well panel using some of the same type of webbing material used by the Warka Water air well (the orange basket looking dealybob from earlier in the thread). The material is apparently quite similar to the netting non-permies buy their fruit in. I've been collecting the bags from friends for several weeks and I'm now sewing them together into a panel, which I plan to frame and position above a collection trough leading to a barrel. It'll be ugly, but it might work. I'll post pics and report my results if people are interested.
 
Shan Renz
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Answering a question from a prior post: the Warka Water is a dew condenser, not a fog collector, and it is used in very dry areas of the Ethiopian desert.
 
Joshua Myrvaagnes
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really, in dry areas of Ethiopia? I had thought it was only in the more humid parts of Ehtipia--that's cool! can you send a link with more info? thanks for posting that! keep us posted about how your thing works!
 
Shan Renz
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http://www.wired.com/2014/03/warka-water-africa/


A repost of the Wired Magazine article posted earlier in the thread.

It appears that the prototypes were set up in the northeastern highlands south of the Nile, which are pretty high elevation but not desert. The Warka Water towers seem to do double duty as fog collectors but only incidentally according to the article. I suppose I'll be able to report more precisely on the workings before too long. I am in South Carolina, more humid than some areas, but generally not until the dog days of summer. It doesn't fog here as a rule, so if this is going to work for me, the design will have to be workable as a dew condenser.
 
John Master
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Jennifer Wadsworth wrote:
Olivia Helmer wrote:I am also interested in building something to collect fog water. I am in California with the drought but where I live we have thick fog almost daily! in some of the forests here when the fog is thick it drips off the trees. the trees act as fog collectors. I have found this thread really fascinating and also exciting.


geoff lawton states in his online PDC that in drylands, you can increase your precipitation up to 80% by planting capturing condensation from trees. In order for this to work in very dry climates, one has to plant a sufficient number of trees which I take it depends on where you are. It is fascinating and thought-provoking. I think Tucson is on the right track with all their streetside stormater harvesting and all the trees they're growing with that harvested "waste" water. They'll eventually increase tree canopy coverage from 5% to 25% and will probably begin to see that condensation effect (and UHI mitigation!) for the entire city at that point.
This is one of the reasons I get excited when I see greening the desert projects work well. It is such a long term goal to take an area that gets such little rain and turn it into essentially a rainforest. Its great listening to Geoff tell stories and show successful restoration of entire ecosystems.

 
master steward
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What advantage do these modern airwells and dew collectors get from being so tall, compared to say a big pile of rocks or the dew ponds?
 
Joshua Myrvaagnes
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Good question. If you get high enough (like 1000 feet up), the air is significantly cooler and so holds less water/is drier. But at ground level, you have some geothermal cooling effect, so that the air closer to the ground is a little (probably negligible, I imagine) cooler and drier and higher-up air would be a little warmer and more saturable.

I think the main answer is that it's an easier form to work with: takes up less square footage on the ground, and the water accumulates vertically as it drips down and falls into one pot rather than needing to be collected into one pot after dripping down a slight slope.

Why do you ask, is there something you need to modify or just avoiding building something tall that could fall over?
 
Steve Farmer
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Location: South Tenerife, Canary Islands (Spain)
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Talking of height... I saw an Israeli design for a water tower using a dissolved desiccant. The tower was tall and as the water fell it created a partial vacuum in a chamber, which encouraged more water vapour to condense in the air inside the chamber. I have also read (tho didn't do any sanity check calculations) that if you have a 1 mile high column of water, the head of water is enough to generate power to run a cooling system that will condense as much water at the top of the tower as is falling thru the turbine at the bottom. Sounds possible and interesting. A mile high tower is a major engineering feat, but a mile high tube running down the side of a mountain? Pressures involved with that head of water are going to be require specialised plumbing and not sure if any current turbines are specced for that pressure?
 
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