Hi Bob Stuart,
Bob, just where to look on the net, for more info, I've been thinking about this approach for a while, it seems very doable. Thanks.

Dan'l

Hi all,
Can anyone lead me to information where various control strategies are discussed to control parafoil kites?

I'm guessing that the control should not be too impossible if good sensors can be developed. In terms of sensors I am talking about letting the controller know where the kite is in the wind window, and which direction it is facing. I suppose an optical method could be developed for low flying kites, but a different method is required when scaling up the system above the clouds. Obviously then the wind direction could also change with height; but let's suppose I just want to sense the kite's position and/or orientation.

Any suggested links where I can start reading?

Regards

Christoff

That giant kite we were just commenting on here is the biggest one
I've seen. For fabric, you might look at the popular arch-rib farm
sheds which are guaranteed for a decade. Sorry I don't know any more
yet. I've just started lurking here, with an interest in a house-
scale installation to pump water directly, as storage for an on-
demand hydroelectric generator.

Bob Stuart

Attachments :



Hi Dave S.:
Well I had to get my minimalist, small-scale, proof-of-concept demo up and running so I was precluded from hearing any of the talks, unfortunately for me, as I really wanted to hear all the details of everyone's projects.

This stuff just exudes fun, whether or not any specific scheme is heading toward an economic energy solution.
I just haven't seen any data at all, from any project. That's why I was asking if you had any stats on any of these. For example Magenn has been running their rotating balloons for years now. Last I had heard, they were using bicycle wheels and fan belts to run Hornet generators. That was a couple years ago. Since they are funded, and I am guessing with millions of dollars, one might suppose they would be disseminating power data by now such as "At 27 mph the turbine makes 50 watts". Combining that with the price of their machine ($20,000?) one might compare the output to other $20,000 installations, and see if it is an economic solution, or "The Bugs Bunny / Roadrunner Hour" combined with "The Whacky Racers" (Penelope Pitstop, Professor Pat Pending, Dick Dastardly, and his dog Muttley).

But we have to remember two things:
1) "High Altitude Wind Power" or "Airbourne Wind Energy" are subsets of the field of wind energy.
2) The Mandelbrot Fractal set manifests at all scales: We've seen it a thousand times: Drag-based machines touted as an advance with vague promises of surpassing existing technology, but never any data to back it up, so they can continue to take on investors' money without any real reason except to drag out the fact that they have another drag machine.

The same holds true of any other machine. If anyone has anything that is remotely close to being useful, it is easy to cite stats, such as: "Machine X was flown for 3 hours at 200 feet in a 30 mph wind (wind speed measured using 10-minute average, for example) and produced an average output of 1000 Watts"

I just haven't seen any data of the normal sort that people in wind energy would call meaningful.

And it is not just people in wind energy, its people in Energy, period.
Wind Energy is a subset of Energy, and in the field of energy, people want to know how much you're making, and what is the cost and reliability.

Realizing that our art is nascent and undeveloped, we should be inclined to be somewhat forgiving as far as demanding complete testing to IEC standrads with 1 year of data for example.

But please realize, if you want your scheme to be taken seriously, this is where the market leads, and what your peers in wind energy and in energy in general will demand at some point.

Why do I say this?

Because I have already been there, done that.
Of course I at first bristled at the notion that my multi-rotor scheme should be held immediately to the standards of existing machines in full production. I was quite miffed (and am still disappointed) that the "scientists" of the world would not simply take my new paradigm and see the advantages and run with it. But we live in a lazy, "prove-it-to-me" world. Remember airfoils were used for 1000 years before "science" rubbed its tired, lazy eyes and produced a "theory of lift".

I quickly found that the reasons the wind energy veterans had for being skeptical were well-founded: It is not easy to make a machine delicate enough to be responsive to 10 mph winds, that also survives 80 mph winds. If you have 1 Horsepower at 10 mph, the cubic power nature of wind says you have 512 Horsepower at 80 mph, and every turbine will see 80 mph winds sooner than you think. So your moped must survive the power of a supercharged V-8. Few fields of engineering must deal with a power range like that. And your machines must survive sun, rain, hail, sleet and snow, not to mention freezing rain, all at speeds of well over 100 mph for most of every day, 24/7/365.

That is why there are two kinds of machines in wind energy:
1) machines that have a measured output and known reliability
2) those that don't;

One group demands data
The response is usually name-calling and declarations of closed-mindedness, threats that someday they will connect their machine to a generator, and the world will see...

I'm just telling it to you like it is. Wind energy is not very forgiving, although those with a toe in the water, even with ill-advised schemes and unworkable machines can raise a lot of money in the current environment.

Sadly we had to abandon searching for funding by the big agencies lest all progress be stalled while we retrenched to the all-talk format. In that ill-advised blog-o-sphere of all-talk, all ideas, projections, and statements can appear to have equal weight, and any skeptical remark by any non-visionary technical reviewer can make months of grant proposal preparation into a meaningless waste of time and resources.

To this day, I, as well as all wind turbine manufacturers, have constant surprises dished out by Mother Nature: completely unanticipated failure modes, from machines asked to incur equivalent wear to a car driven 100,000 miles per year (spinning at least 50% of the time).

Wind Energy is unforgiving and demanding. It is simply fact-based. It demands that you make usable power, economically and reliably. Operation and maintenance costs must be included. The latest fixation here on what to call it is symptomatic of nowhere else to turn, in the face of having of no usable products.

However this is a new field and let's give it a chance to show anything promising. I don't want to throw the baby out with the bathwater. I'm eagerly waiting to hear what results anybody has, and here is a great place to post them. How much power does a Magenn machine make for example? At a given windspeed? No, no it's OK I didn't mean to be mean by asking how much power they make. I know that is a question we are never supposed to ask lest we burst bubbles.

With regard to the "what-to-call-it" conversation, it seems I am being fed conflicting info: When I ask about electric power generation, I'm told to shut up cuz the field includes traction kites, stratospheric yachts, etc. Next I read the field is all about electric power generation again. I'm told the field includes terrain-enabled wind energy, but then someone wants to call it Airborne. I think either the names have to be all-encompassing, or the focus of the group should be narrowed.

Airborne WInd Energy = The APU or RAT on many airplanes provides electric power to the aircraft from a small wind turbine hung below the craft. A very old concept.

High Altitude Wind Power = A conventional tower-mounted wind turbine installed on a mountain top. It is well-known in wind energy that the thinner air should be taken into account.

Terrain-Enabled WInd Energy = existing windfarms preferentially located where the terrain acts to focus the wind resource where the turbines are installed, such as the San Gorgonio Pass, Altamont Pass, and Tehachapi Pass.

All-in-all, some or most of this has been thought of before, then there has been a retrenchment to what subsets of the possibilities offer economic and reliable solutions.

Fixations on what a given name means to small technical subsets of the engineer population may not be particularly meaningful when addressing the masses.

Gotta go high-altitude skiing again now, since Los Angeles just got 3 inches of natural snow in the mountains (added to the manmade-snow base) due to continued persistent cold. :)
Doug Selsam
714-992-5594

Just wanted to let everyone know that due to the major down turn in my sales I have had time in the past week to work on the CAD drawings for my universal power management metering system I will post some pics as soon as I get the design witnessed for my patent book, and the details of my conditions of use by this group. The purpose of this device is to be able to meter ALL forms of mechanical energy on a single, universal platform so each type of energy harvesting can be compared side by side to create a uniform standard. It includes multiple torque, tach and position sensors for every input and segment of the device for the ultimate in calibration and data acquisition. This is meant to be more of a scientific instrument than a generator but will include multiple PTO shafts for generators, compressors, pumps and just about every other form of energy conversion and storage you could think of or imagine. Once the first prototype is completed I will make it available to members of this group so you may make a data base to compare each method and type of energy capture.

-brooks
www.DogJobLabs.com

If you're in space, a high altitude orbit is perhaps 20,000 miles - geosynchrous.
In the atmosphere the term is dependent on the context. For a jet maybe you're talking about 8 miles high. For a kid flying a kite, a mile is pretty high altitude.
For a biologist studying a species normally found at or near sea level, a 1000-foot high hill might be considered a high-altitude environment.
If you're running wind turbines, you should know that 5000 feet elevation has 15% thinner air. The altitude is definitely factored in, and corrected for, in producing any power curve measured at any given site.
For many people, living at 5000 feet elevation is inadvisable because it is considered "high altitude".
Certainly by the time you're at 10,000 feet elevation, in wind energy, with regard to turbine performance, this is considered "high altitude".
Another way to look at it is, currently towers are reaching up to around 300 feet high, so to reach significantly higher than that might be considered "high altitude". Of course, knowing this is a relatively new thrust toward a hopefully nascent technology, 100 feet might be included in the general definition, if it is a step toward higher heights. Words only mean what we allow them to mean.

To pick and choose some arcane definition from some corner of the aerospace world as the only reasonable working definition of "high altitude" with regard to wind power is missing the bullseye I think.

And many here would cite the height above the ground rather than sea level as the defining factor, although a turbine hanging somewhat downward off the top of Mount Everest could be considered to be at a negative altitude, yet be 6 miles into the sky.

Altogether, words are only symbols that mean what people agree they mean, and the context is certainly the most elementary defining factor of what a term means.

For an ant, a high altitude might be 5 feet, depending, again, on the context. For any turbine, if it flies, and is a scaled-down demo or initial prototype, it makes little sense to say it is irrelevant since it is only, say, 50 feet in the air. If it is flying and producing power, that is a big step. Extrapolation is often useful in research of new things.

If a demo site happens to be located directly adjacent to an airport and all the news media have been called, while the FAA has a newly-discovered 50-foot local height restriction, to the point that the airport and FAA call and e-mail during the demo to warn we were pushing the envelope, it is nothing but blind luck that my little demo Sky Serpent turbine was not higher than 50 feet.

Maboomba!
:)
Doug Selsam

Hi Joe and all

Suggestion for the solidity of the article and for some reliable
sources.

A first (shorter) part to describe HAW with references to Cristina
Archer's publications.

The existing article becomes the second consequent part on HAWP devices
and methods.

Furthering,another suggestion:a book on 2009 HAWP conference and on
expected methods.

PierreB

Hmmmm. Doug's points are well taken here.

In *my* energy world, I could not care less about venture capital and
marketing. I need renewable energy solutions that work *right now,* to
power both my home and my business. The utility electric grid is 11
miles away, and even a rich person couldn't afford to bring it in
here...over a million bucks due to terrain.

I attended the Small Wind Conference in Wisconsin this year, and the big
topic was -- "How do you compete with fantasy?" Every homeowner in the
world wants a wind turbine on their roof the size of a DirecTV satellite
dish, that supplies all their energy needs for a year. But it's NOT
going to happen thanks to the laws of physics.

There is only one solution to vaporware -- Ask the "seller" of any
particular wind power product, "Can I visit a site where there's one
working? Can I look at the accumulated data in kilowatt hours per month
vs. average wind speed per month?"

If the answer is "no," then -- it's vaporware. Very few of these even
have a small scale model; wind turbines are very difficult to scale up
and down, but it can be done. But it does NOT take venture capital to
design and test a scale model. Doug did it. So did the outfit I work
for. You can visit actual installation sites, watch the thing spin,
and read energy output per month on real meters.

Where can I visit an AWE installation, no matter how small, observe it,
and read the monthly energy input on a kilowatt-hour meter?

I really do enjoy reading this list; it gives a sense of perspective
since I live off grid and have to generate all of my my own energy. But
*show me the kilowatt-hours per month.* I hate to say it, but flexing
piezoelectric cloth sails, no matter how high in the air, just ain't
gonna do it here -- I need about 100 kWh a month. And my budget is
low....because efficiency is a big factor in cost per kWh. So is
reliability.

Really, the wind power equation should be written as:

1/2 x air density x swept area x windspeed^3 x cP x uptime percentage

DAN FINK


dave santos wrote:

Dear Brooks,

Attachments :

olkite01.jpg

Figher Kites use line crossing friction to cut. Accidental line cutting is a common failure-mode at kite festivals. Many multiline AWE array ideas require moving lines to cross without cutting. A pulley or simple eye on a line is not the best or cheapest solution. A fisherman's line-slider, as used for sturgeon fishing, is.   The slider is a simple plastic tube fixed on one line allowing another to slide past without sawing. It self-aligns over a wide dynamic geometry & resists twisting up. The device enables integrated control & actuation of complex AWE arrays from the ground, much as the human hand is remotely animated by dozens of sheathed tendons.   KiteLab Ilwaco is located at a working port at the mouth of the Columbia River, a world-class center of fishing & boat rigging technology. Most line-handling problems were long ago solved by this brilliant culture. AWE need only study the mature design language to advance greatly.     About the EZ-ZAZOO slider from its website-   "The molding is done in Portland, Oregon and assembled in Ilwaco, Washington. This slider is superior by far to any on the market. It is made with acetal plastic one piece molding. The imported sliders are made with recycled plastic making them very brittle and hard. This causes them to break and groove.    www.ez-zazoo.com   COOIP

===============================
Moderator note: Is this COOIP?

CooIP?

In many locations, the change in wind velocity with altitude (elevation) increases at a greater rate that the decrease in air density. The air velocity can increase up to 5-fold between 100-metres elevation to 1000-metres elevation, while density can decline to 85% the value of the lower elevation. Even a 3-fold increase would yield 27-times the possible kinetic energy with little change in conversion efficiency . . . the decline in output would amount to 0.85 x 27 = 22.95 times the possible power output for equivalent cross-sectional turbine area. A 4-fold increase in wind velocity could yield some 50-times the possible power output.
 
 
YOU HAVE HOWEVER RAISED A VERY CRUCIAL ISSUE HERE, DOUGLAS
 
At a height of 30-miles, we're dealing with 1/1000th the air density and wind velocities of over 450mi/hr (660-ft/sec). Assume 45mi/hr (66-ft/sec) wind speed at 100-metres or 300-feet elevation. The cube of the wind velocity divided by air density would yield no advantage unless wind velocity greatly exceed 500-ft/sec.
 
 
THERE IS MERIT OPERATING WIND CONVERSION TECHNOLOGY AT ELEVATIONS OF 1000-METRES TO PERHAPS 2000-METRES (1/10th the air density). There may in fact be an optimal elevation where the advantage of high wind velocity at higher elevation occurs where air density still allows for an advantage to be realised.
 
Harry
 

---

Interestingly, I FINALLY see some learning--and teaching going on. If only it weren't quite so shrouded in "I'm rubber and you're glue" shenanigans.

Doug has some really good data on his stuff--stuff which not only exists, it overcomes some (though not all) of DaveS' opposition to Doug's phenotype. DaveS has some really good arguments (though not all) which serve to validate inexpensive soft kites for energy production. The concept that only one of these devices can or should exist and that the other needs to--post haste--fold his tent and slink away, is the height of silliness.

Doug, DaveS makes a good argument when he states that commecially-available kite power isn't necessarily the primary objective of his work at this point. Early work with heavier than air aircraft did not produce--never could produce--commercially viable products as their first prototypes. To insist otherwise is silly.

DaveS, cloth is astonishingly short-lived when it is allowed even the tiniest bit of flapping. I have seen zero studies--even zero proclaimations--that cloth structures could *ever* be cost effective compared to carbon fiber, fiberglass, or even wooden turbine blades. There are other compelling reasons to investigate membrane structures, but power/$ expended may--and may not--be one of them. Please, supply some data--even surmise--in defense of your position?

DaveS, some time ago you decried--still do--torque tubes to bring power to the ground. Yet you ignore Doug's writings on bias-wrapped tubes, tension-supported torque tubes and the general state of the art in cheap, factory built--and available seconds --scrap--materials and their place in the sky. He's shown data suggesting pretty compellingly that currently available, light, cheap torque tubes are sufficient for 10-20 kw (a size you seem particularly interested in, judging from your own work), yet you continue to berate him at a theoretical level. Why?

Doug, have you investigated high pressure inflated torque tubes? Think aircraft fusilages, not kitesurfing bladders...

Doug, you persist in demanding power curve numbers--a fair position. Yet you decry all attempts by Brooks, DaveS and others to produce exactly that. Perhaps more flies may be attracted to honey than to vinegar?

Doug, turbines kill birds. This is undeniable. DaveS, so what? Humanity stopped using a *very* safe insecticide--and doomed more than 100 million humans to death in the last century from malaria and other tropical diseases--in order to save the Brown Pelican. Not the White Pelican which wasn't in danger, only the Brown. Fair tradeoff? Perhaps. They are beautiful birds. I've said elsewhere that strikes against ordinary buildings kill 3 orders of magnitude more birds than wind turbines do. The bird issue is neither compelling nor ignorable, IMO. Personally, I have better things to do with my design energies.

I'm amused by others, (not Doug--Doug has raised a lot of investment capital) who proclaim that venture capitalism is some sort of bugaboo. I *love* Dan Fink's suggesion that he needs no part of investors, only a profitable, cheap method, created by others and provided to him in a manner cost-effective against the cheapest of Chinese labor-produced, in order to solve his own problem. Dan, I conclude that the car you drive is a hand-build prototype, lovingly crafted for you from first principles and scrap materials by people who do not value their time? You are probably typing on an Apple I knock-off you built yourself in your garage, untouched by investor-paid development? That you eat only home-grown organic food is a given--but where do you get your pre-Industrial Revolution seed stock? I can tell you are young--under 40 certainly, as I find it unlikely you'd have survived disease and accidents--hell, loss of teeth-induced starvation--for much longer than that without investor-paid medical developments?

Bob and Dan'l; Cuben fiber cloth for kites is a pretty good idea--having built a number of kites larger than 3000 sq ft and having engineered and sourced materials and technology for 15-20,000 sq ft kites, I can tell you with some certainty that these are possible, but how are you going to pay for them? The cloth you mention sells for on the order of $10/sq ft, lasts <10^3 hours in actual use. How are we going to even procure enough of it for a prototype? Don't say "investors"... ;-)

Dave

Greetings all,

I read from three different research papers that HAWT were not feasible above 36,000 ft; one paper said 28,000 ft., because of air density, the point of diminishing returns. Harry, are you saying that that point is much lower?

Lynn Potter

Dear Dave S.:
A lot of yer frusterbation is, yer a "torsion-tube denier" a-a-a-and a self-admitted data-avoider.
Doug

Of interest and relating to cloth, MARIMAC industries has knitted large pieces of fabric using fiberglass thread . . . very light, very high tensile strength and resistant to UV. It is possible to embed either teflon or silicon into the fiberglass fabric to make it water-repellant and water-resistant.
 
 
Harry

---

I would say that 28,000-feet to 36,000-feet may be the maximum viable elevation. There is great potential to develop wind energy technology at elevations of over 2000-feet to the maximum viable elevation. At 10,000-feet, we're still dealing with 75% of the air density we have near ground level at most locations. 
 
I will not speculate as to the optimal height for any one design of airborne or high-altitude technology.
 
 
Harry

---

I had a thought last night about the ideas pitched earlier
on the "kite-pulling-boat-dragging water turbines" type.
So you have this tanker sailing around
charging up batteries and then docking and discharging to a grid,
--after all, we have tankers that go across the ocean doing
pretty much the same with oil.

It struck me that: Wow!, don't we get container ships
full of batteries? Not sure if that is true, but, if so,
someone could come up with a "Charger Ship" that charges the
batteries for free on the way to its destination. Just a thought.
-brooks
http:www.DogJobLabs.com/

Would you consider producing hydrogen for fuel cell motor cars by your innovative method?
 
Harry

I saw a flag flapping in the breeze today... it is the same one that has been out here since I first bought my property. It's never been taken down and is still in one piece. Just an observation. -brooks

File:Kettenwindgenerator 2.JPG - Wikipedia, the free encyclopedia

Looks like it won't harm any birds.

Harry

Though, it has lots of drag.

This LOOKs a lot like the CAD file I started working on a few hours ago but mine is kind of a hang glider type frame work in the center and more like a para sail with lines on the outer blade tips and has a tensegrity tubetruss connecting the outer edges of the frames together part to better handle the torque. I'll try to post some pics in a bit.
-brooks

Its not either of the 2 you just mentioned and although my universal power device is meant to solve SOME of the problems you will have,(differential equations for one) it does not solve all of them. I still think single line is a big plus but everyone should do what works for them.
  I'm also working on an auto controller/actuator for a pulsing drogue chute design at the moment so more on that later.

-brooks

Well I'm not claiming the method of harnessing the energy is mine of course my my innovative device for routing energy could be used to produce hydrogen. I was also wondering if an oil tanker could be converted to a giant compressed air tank. In any case the device test all kind of energy capture routing and storage to see what works best for different purposes. It may be possible to actually MAKE money off of the transport of goods. If that becomes the case I will expect free international shipping for all the goods I have been paying out the wassooo for and they still can't find. Don't get me started on that subject....
-brooks

Hey gang,
I saw some mention of a AWE wiki page someone set up for this group to add to but I can't find the email. What is it the address and is there a login needed to add/edit it?
-brooks


Brooks and all,
Struggling with "high" ...perhaps LA, MA, HA are categories of "high" for the emerging AWE tethered and terrain-enhanced cabled...AWE:
High Altitude Wind Power
http://en.wikipedia.org/wiki/High_Altitude_Wind_Power
For earth:
LA-HAWP ? 0 to 999 ft ???
MA-HAWP ? 1000 ft to 7999 ft ???
HAWP ? 8000 ft and above ?

For other planets?

M
.........................

Hi Brooks,
 
Hydro Quebec generates hydrogen using excess hydroelectric power during the northern spring melt. The hydrogen is then shipped to Europe using ships equipped with giant spherical pressure chambers that can also carry compressed natural gas.
 
It may be possible to equip such a ship with additional water turbines to generate hydrogen while it is being towed using airborne traction kites.
 
Harry

---

In area where we see a lot of wind turbines, a brand-new flag lasts a few months before it is shredded to tatters. Cloth that is held to a shape and resin-impregnated and UV-protected can do far better.

Special thanks to all who sent notices in November 2009
for advancing the associated web. See on the page that
there are open topics; that is, each cell may be expanded
by further notes and related links on the topic of the cell.

http://www.energykitesystems.net/notices/2009nov.html

Every time a large-diameter turbine blade (200-ft to 400-ft diameter) rotating at 10 to 20-RPM passes the tower, the sudden change in dynamic (a.k.a. stagnation) air pressure produces a "shock wave". Evidently a series of such "shock waves" seems to be able to damage the cloth of lags.
 
Low-frequency sound waves can travel great distances (eg: 20-miles at the human sub-audible level). Thermo-acoustic engines convert heat to low-frequency sound waves that drive a linear alternator to produce electric power. Recently, more communities have begun to reject proposals to build new wind farms in their neighborhoods or near the communities.
 

Harry 

---

Compressed air is not a good energy storage medium. In small
systems, it has far less energy density than lead-acid batteries.
For efficiency, large systems would need to be insulated to retain
the heat of compression, or rigged to use it with sterlings or
similar engines, at great loss. Unlike with hydrogen or liquid
fuels, the whole energy of the compressed air tank is instantly
available. It is a high explosive, like having a tank full of dynamite.

For various reasons, hydrogen is the energy of the future, and it
always will be. It is bulky, leak-prone, and a potent greenhouse gas
itself. Given any choice, it seems best to synthesize liquid fuels.

The one glimmer of hope is using air compressor heat directly, for co-
generation on land, and then re-expanding the air in stages, picking
up heat from ambient sources to enjoy the sort of over-unity results
that heat pumps get, while supplying power on demand without batteries.

The great insurance companies started out combined with an inspection
service to reduce boiler explosions. There's good reason for all
those stuffy old regulations about steamfitters. A big air tank
would need constant care or great separation for safety.

Bob Stuart

Hi Dave S.:
We just call them driveshafts. Like in your car. Unless yours is powered by strings and pulleys. My patents explain how separating the base stations places the Earth in compression, and the driveshaft in tension, best utilizing the strength of our minimal materials. For airborne versions, the tension is provided by the cumulative thrust loading of the rotors.

I learned long ago, if I spend all day blogging away in response to phantom problems cited by naysayers and those who don't understand what I'm doing, I get nothing else done.

So, while this is fun, I have orders to fill and deadlines to meet. Part of my job is to monitor failure modes, such as when solid steel is sometimes eventually ripped apart by Mother Nature, or we just make too darn much power and barbecue our generators to cinders.

Repeating the historical learning curve of wind energy is not on my agenda - way too much work - much easier to note and accept what has already been learned by others.

What I'm doing is the next logical extension in the learning curve of wind energy, applicable to land-based applications, and because the most extreme examples of the multi-rotor concept reduce weight (= material use = cost) by more than an order of magnitude, these lightweight versions are also suited to airborne applications. Note that they also solve many major existing engineering challenges in wind energy, period. I did not invent the propeller. That took 3000 years. I just note the progress made and take up where previous innovations left off - at the end of the 20th century. As I have explained, using triangular cloth sails for pulsating duty cycles is to go back at least 2000 years.
OK enough of the blog-o-sphere - I gotta get back to the at-mos-phere! :)
:)
Doug Selsam
http://www.selsam.com

Hi Bob Stuart,
 
How is the winter time wind situation in the northern Saskatchewan region, especially the wind speeds at 500m to 3000m elevation? You may have to pump compressed air into underground storage caverns near your location due to the water shortage . . . perhaps there may be someway to transfer the heat-of-compression into thermal storage and use it topreheat compressed air prior to it being expanded in turbines.
 
 
Harry

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