Leaving arches, meshes, and domes for topic threads elsewhere, 

Hi Friends,

Excuse me not uploading the PDF of Marchetti. There are some copyright problems what prevent me to do so. But JoeF have found a link where you can download the full paper:

http://webarchive.iiasa.ac.at/Admin/PUB/Documents/RR-75-038.pdf

Regards,

Gabor

Hey Joe:
You already spelled out one great way to go.
I see the non-field of AWE like this:
Imagine a bunch of PhD's trying to figure out a way to move a pile of dirt from point A to point B. Sitting there are a car, a shovel, a trailer, and the pile of dirt.
How long do you want to listen to all the goofy excuses the PhD's will come up with to avoid having to pick up the shovel and get started? How long would they avoid even discussing the idea of connecting the trailer to the car? The answer is they would never get the dirt moved. Picking up a shovel is not in their job description. Since it doesn't require a genius, it just doesn't sound interesting. No lasers, no computers, no microwaves, no liquified air in the stratosphere, no giant improbable yet frail structures that produce nothing and lead nowhere, no big mystery, just take the tools you have and do the job. That sounds like work doesn't it? And did they spend all those years in school to have to do any work? No it was to avoid ever having to work.
You mentioned picking up a shovel and filling the trailer and connecting it to the car and driving it to location B the other day. I like to feel I had some role in pushing you in a direction where the pile would get moved. Congratulations for identifying the fact that there is a trailer, a car, and a shovel available, waiting for anyone to decide to move the pile. Just in case anyone really wants to move that pile of dirt.
Oh geez I can hear it now:
"Yes that's it! Using kites to move piles of dirt! Kite-powered strip mining! - giant trucks pulled by kites!"
OK I give up - I tried.
Have fun liquifying air in the stratosphere and using single kites to intermittently pull on a string everyone...
:)

Good example Joe:
Thanks for pointing out: the car, trailer, and shovel combination has been known since 1937.
That's almost 80 years of laziness. In all those years nobody can pick up the shovel, fill the trailer with dirt, connect it to the car, and go.
But "Profethor Crackpot" can sthpray you the answer between projected food particles from his beard and braces, not caught by his bowtie:
"The soil can be heated by microwaves until it expands and jumps to the new location! The microwave generating device can be mounted on the trailer, slowly nudged forward by multiple collisions with the car, which can be guided by computers, GPS, and lasers! Subsequent microwave heating can slowly move the pile to the new location! Let's make sure we include our imagined concern of at least 20 government agencies and talk endlessly about their safety rules for slow traffic, oversize loads, safe microwave transmission - ANYTHING to avoid picking up that shovel! That would be when the fun turns to work. Too bad the world is so afraid of getting their hands dirty. So nice to see how many geniuses there are in the world.
:)
Doug S.

R. Lozano Jr, 

One of the wings was signed by a relative of Lawrence Hargrave: 

"..... besides flight experts, we need among others physicists, chemists, caloric engineers, electric engineers, computer experts, experts of remote control and telecommunication, meteorologists, experts of electric vehicles, etc. But don't forget about lawyers, patent attorneys, financial advisers, etc. You can see that the theory and praxis of “flying objects” is a very important, but probably neither the most important nor the most expensive part of the whole project. That is, "flight experts" have lost their priority in the project. A physicist or a chemist who has solved the remaining problems of energy storage can say that it is a chemical technology. It is not a simple situation and I think the solution cannot be found by applying departmentalism. Regards,   Gabor "
JohnO
President-protem, AWEIA
www.aweia.org
Sent from my BlackBerry wireless device from MTN

One of the core classic train articles in in th issue:

For almost three years, kPower has had a sponsoship agreement with Austin Energy; for the city electric utility to have a first-option in beta-testing its AWE, in exchange for early angel funding Austin Energy is famous for leading Texas to be a world windpower leader, under the visionary leadership of Michael Osborne and Roger Duncan (two old friends of mine from the '70-80's). The kPower contract is just on of may amazing public intitiatives from Austin's energy innovators. Praise also goes to Michael Breen, kPower's first CEO. for bringing Austin Energy early into AWE.

kPower is soon to present an initial small-scale beta-ware for Austin Energy to assess. In a longer time-trame; Austin's Fayette Power Plant is a large coal-fired facility that planners and public wish to decommission without economic damage,. kPower will be preparing a plan for Fayette as an study case, whereby AWE might progressively replace coal generation, starting small, and bootstrapping growth.

Austin Energy AWE participation is a ready model for progressive electric utilities around the world. A question for JoeF: Are there other similar models of local public-prvate AWE cooperation?

Dear Mr. Einstein:
The history of wind energy goes back 3000 years that we know of.
During that time, a lot of bad ideas have been tried and found lacking, and the better ideas have slowly taken hold.
One thing we've learned is that there are UNLIMITED numbers of (bad) ideas that could, potentially, without violating the laws of physics, harness SOME immediate energy from the wind.

However,
The bigger lesson is that MOST of these ideas take more energy just to MAKE them than they would return over their lifetime. That is usually reflected immediately in a cursory economic analysis, which reflects the cost of energy needed to mine the materials, transport them, build and install the machine, etc.

What we see over and over are newcomers to the field of wind energy proposing some method that merely overcomes the FIRST basis for rejection of such ideas: "Does it violate the laws of physics?"

But "not violating the laws of physics" is not NEARLY enough to say it is a good idea, or even a viable idea. Congratulations to that person for not being the absolute lowest level of crackpot by promoting perpetual motion, but there are further levels that are not quite as blatant.

If someone is proposing gliders flying in and out of the jet stream to harness energy, for instance, storing that energy in say batteries or a tank of liquified air, returning to Earth, swapping out the storage and using it to generate electricity onto the grid, they should include a workable scenario, with at least a basic economic analysis that shows the idea COULD be "in the ballpark" of actually BEING a solution instead of just "sounding like it MIGHT be" a solution.

Nobody would reasonably ask for a COMPLETE economic analysis for a system that is just a raw idea - the details would obviously have to be worked out over time. But some BASIC indication of economic feasibility is the only way to say it could possibly be a "good" idea versus just one more of millions of false trails and ideas that are "close but no cigar".

Example:
Include the lowest likely cost of a glider or fleet of gliders capable of flying round trips in and out of the jet stream. Estimate weights and costs based on what is known today.

Figure a low-cost way to launch and land - an airport? What is the lowest cost one might envision just to keep these gliders circulating? Estimate cycle times - how many flights per day can one expect for each glider? What is the cost of the onboard turbines? The cost of the onboard energy storage? The predicted life of the glider? Of the batteries? Number of total cycles before replacement? The cost of extracting the energy of the liquid air on the ground and turning that into electricity?

Given such elementary estimated parameters, figure out the value that the amount of energy produced could be sold for. Use the most optimistic numbers possible to make sure you don't "throw the baby out with the bathwater". Then you might start to see if it is a good idea, a potentially workable idea, or just an idea that, while not violating the laws of physics, violates the laws of economics.

One helpful approach is to analyze even a PART of the proposed system, and examine whether, even if the other parts of the system were FREE, could the one PART of the system, by itself, ever pencil out? If so, one might preferentially develop just that part of the system. For example if one determines that liquified air is an economically-viable method of energy storage, imagine if the electricity were FREE, outline an economically-workable scenario for just the energy storage part of the proposed system, and figure out if THAT part of the proposed system could pencil out by itself, before adding it to another idea that has also not been shown to pencil out.

If energy storage by liquified air pencils out, for example, maybe the best course of action is to develop that method of storage to arbitrage the spread between off-peak and peak energy prices, and save the glider development effort for a future day. Sensible?

While the most common "new" idea in wind energy is in fact the oldest idea in wind energy - the "merry-go-round of sails" known as a Savonius turbine, let's remember, there's NOTHING about a Savonius that in the least violates the laws of physics.

Nope, a Savonius machine is solidly centered in known laws of physics. In fact this obvious lack of any doubt that the basic concept is physically workable is the reason that most promoters of Savonius machines believe they have risen to the level of an Einstein or "The Wright Brothers", as they almost always claim to be when challenged, not on the basis of whether phtysical laws are VIOLATED, but on whether they are being OPTIMIZED to a point that these economic principles can also be overcome or at least met, to the point that an economic solution could at least be predicted as POSSIBLE or likely.

Nobody is asking for a miracle, just the slightest "light at the end of the tunnel" with regard to an economic analysis. While it would be impossible to analyze every single detail, it's a good idea to try and at least give SOME indication, on SOME (ANY!) comparative basis, of the possibility that the raw concept COULD, under SOME optimistic scenario, have a CHANCE to contribute toward, rather than merely drain, total production of economically viable energy.

Without at least SOME basis for economic analysis, such blue-sky hypothesising by itself, does not really get us there, and does not quite rise to the level of a comparison to "Einstein" or "The Wright Brothers", except perhaps on the basis of humor, sarcasm, or just sounding like so many crackpots that we can reliably predict will continue to come and go in the field of wind energy, always citing the Wright Brothers when prompted for details or a cursory economic analysis.
:)
Doug S.

Use the shovel to put the dirt in the trailer, connect the trailer to the car, drive.

Newsflash:
If ANYONE demonstrates ANY lower-cost, or cleaner-at-an-acceptable-price method to supply power, it will be considered by those who consider such things (utilities, investors, energy providers, energy purchasers, etc.
If anyone actually refines such an idea to a level of reliability, safety, economics, aesthetics, and availability, etc. to meet market demand, they would have a viable business and no shortage of customers.
As GE told me years ago, it's all about COE (cost of energy). Demonstrate such economic superiority and it would be difficult for utilities, energy providers, etc. to NOT be interested.
As always, the opportunity is there for anyone who can provide energy at a lower cost. Some things never change.

Einstein didn't even profess to be smart, as a starting place.
One thing he did well, was to back up his theories by "thought experiments". These "experiments" could be "conducted" on-paper, or in one's head, without actually building anything. They just applied logic to a hypothetical situation to see what fell out at the end.

The thought experiments were so simple and so successful, so difficult for skeptics to argue with, that they helped people to understand a new way of thinking. When experimental results started to confirm non-intuitive (for most) outcomes that agreed with the the new theories, the new theories started to gain acceptance.
The thought experiments were such that anyone willing to mentally walk through them was quickly convinced.

There can only be so many "Einsteins". The basic rules of physics are not rewritten as often as the rules of physics are applied to specific situations. Wind energy can be conducted, for the most part, without even applying any of Einstein's theories, leaving out solid-state electronics which are often cited as applying Einstein's physics, but which are also usually applied by applications engineers without specific expertise in quantum physics. Newtonian physics is a sufficient approximation for most wind energy engineering.

It would be a mistake for a mere practitioner, or worse yet, a wannabe practitioner, of an art using physics, to mistake their contribution for the equivalent of re-thinking the entire field of physics.
However, if one DID want to try and employ some "Einsteinian" type of thinking to a problem, it seems that the "thought experiment" might be one such way.

For example if one wanted to fly airplanes in and out of the jet stream to gather energy, such a thought experiment might be:
Imagine an airplane that could travel at 600 mph, based on current airplane technology. Imagine the cost is 1/10th the cost of a jetliner since it needs no seats, restrooms, windows, lights. TV's galley, etc. Imagine it can produce energy at the same rate as a jetliner uses energy. Imagine its cycle time to get to altitude and collect the energy and land again is 2 hours. ON-and-on-and-on with enough details where you can say "given these assumptions, one can confidently state that the cost of energy could be $X.00/kWh."

Now that would be applying Einsteininan-type thinking.

But
Far from even approaching an Einstein-level of thinking, most wind energy wannabe inventors do not even understand the problem they are trying to solve! They imagine their task is to "not violate the laws of physics". Nope, that's true of anything you want to do. That's a given, no matter what you're trying to do.
The task in wind energy is to present a method that can be said to offer the promise of economically harnessing energy - it must be sustainable, not just possible. It must be economically advisable, not just technically possible within the bounds of raw physics.

So, once a professor sees that his task is to introduce an economically-viable method of wind energy generation, rather than merely pointing out one more non-economical and inadvisable false trail, he has taken the first step toward not being the next "Professor Crackpot", and instead astute people reading his proposal will say: "These assumptions are reasonable and the proposed scenario based on them seems logical, therefore we are impressed enough to acknowledge the possibility that a new method of economical power-production may have been introduced."

See the difference in identifying the task? In the approach?
The Einsteinian approach is not to misidentify the task as "finding any way to produce electricity that does not violate the laws of physics". Like "find any theory that can actually explain observed physics". No that is not the task this time. That was Einstein's task. The task here is to optimize a method of producing electricity economically. That requires proving the economics, not just showing that the physics can work. You can use "physics that work" to make a turbine that costs far more than the energy it could ever produce, and many people do.
:)
Doug S.

Do you guys understand that concentrating ducts, shrouds, concentrators, etc., (different names for the same basic idea)
DO actually greatly enhance the windflow through a rotor?
The reason I ask is when I read what you guys write, I get the impression you are in denial of the simple fact that these devices are well-known to work.

I get the distinct impression that you are both trying to say that there is no enhanced power at the rotor.
Nothing could be further from the truth.
Not only do concentrating funnels work, you can put one backwards on the back end and use the downwind vacuum to also enhance power. And they two techniques can be combined - a concentrator on the front and a vacuum diffuser on the back end.

There is no debate that these devices work, and work very well.
The reason they are not advisable is NOT because they don't WORK - they DO.
The REASON is because they must be engineered to survive 100 mph winds, so they must be made as strong as the blades themselves.
Blades have maybe 2% or 3% solidity with regards to the whole disc.
The ducts and shrouds on the other hand have 100% solidity. That high solidity translates to high material use, high weight, and just mounting the darn things gets prohibitive - now all that extra material needs a beefier yaw bearing etc.

Another reason is the higher windspeed makes the rotor noisy, so they add more solidity to the rotor like FloDesign and reduce RPM, which of course then requires a larger generator, so they threw away about half of whatever advantage they had! Band-aids on band-aids.

What I try to explain to the airborne wind energy people (to little avail) is that merely thinking up a machine that "doesn't violate the laws of physics" is not enough. A million goofy ideas can "not violate the laws of physics". Every idiot promoting a Savonius thinks they are the next Einstein based on their machine "not violating the laws of physics".

A wind turbine must go far far far beyond merely "not violating the laws of physics". The goal that most newbies don't even KNOW about is OPTMIZING the machine for the laws of ECONOMICS. It's an economic exercise, that uses physics, but the real thing that needs to be optimized is the economics. The physics is just your tool - a shovel. The hole you are trying to dig using that shovel is economics. If your design violates the laws of physics, you are obviously a non-starter in the race. for all the rest, merely not violating the laws of physics is not enough, just a starting place.

Yup Dave as you point out most of what you read here is absolutely clueless. In so many ways!

Doug S., 

Among economic problems:

• Land and space used
• Electronic control management
• Reliability
• Quick wear of materials due to various movements of kite
• Losses of energy by conductive or mechanical tether
• Low efficiency (like for land and space used this problem can be not very important if the cost of space used is not too high
• High level of maintenance...

Now probably AWES are not so efficient as conventional wind turbines.

 

PierreB                    

"At the AUVSI Unmanned Systems conference, New Mexico-based startup Titan Aerospace unveiled the company's prototypes for "atmospheric satellites" -- autonomous unmanned aircraft powered purely by solar energy and capable of staying aloft at high altitude for up to five years. " 
Almost orbital, solar-powered drone offered as 'atmospheric satellite' 

TECHNOLOGY

19 AUGUST 13  by SEAN GALLAGHER 
===========================================================
One day FFAWE will be showing story in such conferences .....

Hi Joe:
The qualification of "not breaking the laws of physics" does not need to be stated per se. It is understood. The promoters of dubious wind energy harvesting ideas unconsciously believe that once they have grasped the slightest elementary concept of wind energy physics - such as a surface can be pushed by the wind and thereby move with the wind - which even a child can see - that they are the equivalent of Einstein, The Wright Brothers, etc.

It's symptomatic, and we've come to realize that with wind energy being such a magnet for crackpots, debunking dubious wind energy ideas can be more a mental health issue than an engineering issue.
By the time they are patting themselves on the back for being "The next Einstein" (again) (sigh) it's hard to NOT point out how symptomatic that is. At that point we can identify the references to Einsten and the Wrights as just one more (sigh again...) symptom that we've seen for years and years.

If one wanted to go "Ad Hominem" and start calling people "idiots" etc., as those in any art do when confronted with newbies making classic mistakes, they would first cite all the physical and engineering reasons why the person promoting some long-disproven notion could thereby (in a good-natured way) be called an "idiot" (Hey there is a cure - experience!) then cite the further evidence that "They think they are The Wright brothers too!" as icing on the cake of idiocy.

Most promoters of these dubious concepts have no idea what the problem even is - generating power more economically. They think the problem is finding any method that could possibly generate any electricity whatsoever, under some optimal conditions, of which there are unlimited ways! Unlimited! All those ways don't matter. The only ways that matter are the ones that help - that give you more electricity for less investment - that lower your electric bill - that is the goal.

We already HAVE electricity. We already HAVE wind-generated electricity. The thing that matters now is price, not how complicated it can be made. Merely being more complicated is in fact COUNTERproductive.

Sorry for coming from an actual background in wind energy, where we've already heard most of these bad ideas over and over without the airborne aspect. It is good that this group has two of us with actual experience in wind energy lest the discussions go totally off the rails. The rails are "people would like to lower the cost of electricty". To lose sight of that is to be shooting in random directions.

By the way, my impression is that people even using the term "ad hominem" are still trying to prove they are the next Einstein by throwing out a little Latin that most people might have trouble understanding. Nice try but most people here have no understanding of what the challenge in wind energy even is, and don't understand the first thing about wind energy, let alone have any real solutions to offer. Einstein or no Einstein. Most think adding an airborne aspect is an excuse to never learn the basics 9wheee!) - nope, it's still wind energy.

Anyway, with regard to Gabor's idea per se - flying gliders in and out of the jet stream to store power, to later be released into the grid below - I like the idea. Sounds good to me if it accomplishes the goal of cheaper electricity. Does it have a chance of that? I wish I could see some numbers indicating that it has a chance for economic power production. That would be the next step, and the only meaningful step, after identifying the raw idea.

Show why it is not just one more of millions of possible ways to make SOME power at SOME cost. There are unlimited ways to do that. No advantage has been shown over all those millions of other hypothetical ways yet. I'm just pointing out the reality that we in wind energy have learned to take into account.
"Nice idea - let's see some numbers"
Take that phrase and have it tattooed on your forehead!
:)
Doug S.

MFC  ::  Macro Fiber Composite
http://tinyurl.com/MFCimages 

I had to read all 10 pages to get to the punchline at the end:

"the efficiencies are not sufficient the meet to requirements of minimum energy for devices, the desired electricity could be obtained with the advancements of piezoelectric materials and the storage elements."

Translation "current piezoelectric transducers are not efficient".
Translation to common parlance: "piezoelectric stuff sucks"

I would add that the methods cited to actuate the piezo elements resemble typical known missteps in wind energy, such as converting rotation (good) to reversing cycles (bad). That is a step backwards.

I have to say I never heard of soft piezoelectric elements which is interesting and possibly more promising than the hard ones since they allow more motion(?).

Link to the project description 

http://en.wikipedia.org/wiki/Vladimir_Shukhov

Dear Ms. Sheapard,

mission of AW-consortium is very honorable. You really brings together different groups of inventors and give investors the opportunity to learn and existing projects in this area. In fact, you are the axis in the development of this new field of energy.

Unfortunately, the principle of your organization involves funding from inventors who generally have ideas but do not have the money to carry them out. The result of this activity is wasting investors money for publicized projects, which often do not have a chance of success, or they may work in a narrow range of altitudes, winds capacity.

Another negative effect of this policy is the lack of awareness of investors about the set of concepts and pilot projects of small groups or individual inventors. The present inventors do not have the funds for a good advertising campaign, do not have time for this, and just do not know how to do it. In the mass of such projects can get lost real nuggets that could be a breakthrough in the AW-energy, which we all dream about. I hope you also dream about it.

I suggest you create within your web site project hosting service for individual inventors. This will create a database that is filled with the participants themselves. It does not require a major investment. In fact, this may be used already existing on the internet services, adapted to our theme.

This will give you the ability to unite people, not by the existence of the initial capital for self-promotion, but in terms of the availability of fresh ideas and the desire to implement them in real projects. Perhaps, then, AW-energy will stop to be a way of making money out of air and turn into a real industry.

This outdoor space can be a place for discussion of project participants and help at an early stage to identify their shortcomings. This will provide an opportunity to avoid unnecessary expenditure of investors' money, and to identify potential projects so far remained in the shadows.

Addition to such a database could be technology crawdfunding, successfully operating in other online projects.

Since AWE takes up most of my life, personally I am ready to pay some money for place in such a database under certain guarantees popularization of my projects among business angels. I think that my view is shared by other inventors AWE, in particular, the AWEIA.

Best regards,

Alexander Muzhichkov
awenergy.ru

Yes, Muzichkov.
AWEIA shares your concerns which is why AWEIA had consistently been open to all.
The business database subscription service you advocate would have been a welcome service from the AWEC(Consortium) if only AWEC were sincerely transparent, open and committed to fair dealings to the benefit of all AWE stakeholders irrespective of 'purse-size'.
The continued exclusion of AWEIA from the AWE Conference(s) organization remains an open negation of the Consortium's professed desire to "come out of this (Berlin 2013) conference with 'One Voice' for the industry".
AWEIA yet reserves airbornewindenergy.com to serve the commercial interests common to all stakeholders and suggestions and propositions such as you made here are further welcomed to guide it's proper design and eventual development.
Business enquiries can be directed to: ceo@airbornewindenergy.com
Best lifts.
John Oyebanji
President-protem,
AWEIA International - www.aweia.org

---

 

Hi Joe:
It's a sexy-sounding idea. If it doesn't work out per se, maybe it could lead to an idea that pencils out as an economical power solution.
I have a few questions (holes in the story) for whomever is promoting this idea:

1) liquified air energy storage: Compressed-air energy storage is not some new topic. People have tried to market cars using it. It's a perennial "new" topic in wind energy "Why not just use compressed air?" - I've probably read about 100 proposals for storing wind energy using compressed air. So far none has panned out. Usually they end up recommending lead-acid batteries instead.

What I don't remember EVER hearing was to actually LIQUIFY the air. I have no idea why. I understand why just compressing air has prohibitive losses when one tries to get the energy back (not very efficient). But I've never heard of the liquifying part. So I guess what I'm asking the proponents of this idea for is some evidence that it "makes sense".

First I'd like to know what work has been done in liquifying air as energy storage: What are the efficiencies, advantages, drawbacks, challenges to overcome? Any previous applications? Why or why not?

Is there any reason to consider liquifying, per se, versus just compressing air? Is there a reason we should truly consider liquified air at all? If it is a brand new topic nobody ever thought of, does it not merit its own development effort independent of AWE? And if unproven, why would it be included in an already unproven AWE scenario? Is it not adding a second unknown to a first unknown, to the point that all meaning is lost from the first ideas since one has no way to asses the addition of the second idea?

2) Do you have any numbers to put to the projected economics of such a system? Can you give anyone a reason to say "This is a reasonable idea."? Can you tell us "an off-the-shelf glider costs X, the air-liquification system will cost Y and weigh Z, so each module will weigh A and cost B. The cycle time to the jet stream and back will be C and the amount of energy collected per cycle will be D. The process to extract the energy on the ground will have efficiency E, and the cost of the equipment to extract the energy will be F. The cost of putting that on the grid will be G. Therefore these numbers suggest we would be providing grid-electricity at a rate of less than 4 cents kWh."

Do you have anything like that? Or a way to compare any predicted cost level and power output level? Any indication whatsoever that this idea goes a single step beyond "merely not violating the laws of physics"?

In short, is there a single fact giving even the slightest indication that this is a viable idea? Is there any argument to be made, on any basis whatsoever, that this could provide energy at anywhere near a reasonable cost? Any set of assumptions that could make this pan out? Can you cite any line of reasoning indicating the efficacy of such a proposed scenario? Anything at all?
Just wondering...
:)
Doug S.

I meant where is the progress point of Mothra as an airborne wind energy system today? What progress has been made since it first flew? Just wondering. I wish we could all get more done and get more of our dreams up and running.
:)

Alex:
Thanks for providing a link to details of your proposed method for a concentrator/diffuser for a wind turbine.

Referring to your descriptiom:
"In this pilot project diameter at the entrance to the shell 2m, a minimum cross-sectional diameter of 0.3 m, it is theoretically increases the rate of 36 times (at a wind speed of 9 m / s in the supersonic forward transition in a minimum section"

So you're saying your concentrator can increase the wind speed by 36 times? Do I have that right? That sounds really good. I don;t think I've ever heard that number before. Is 36x in any way realistic? Can you show any evidence for that claim? Any evidence whatsoever? From where did you pull that number? (Somewhere the sun doesn't shine?) You spend "most of your time" doing this?

Much work has been done in the field of ducts, concentrators, and vacuum diffusers for wind turbines. So far all models and companies pursuing them over many decades have failed. But there is no lack of experience. Can you point us to previous work indicating the maximum speed increase for wind concentrated by such a funnel? What is the highest multiple of wind speed yet achieved?

:)
Doug S.

In a Venturi nozzle,the flow of air is constant,so air speed increases when area of minimum cross-section decreases.For example if area of maximum cross-section is two times that of minimum cross-section,air speed is two times at minimum-cross-section,kinetic energy being 2 times that at maximum cross-section.It is a very good new BUT the reality is as following: air speed is quite lower when air enters into the concentrator/diffuser,since it is an obstacle for air circulation.So the efficiency of Venturi nozzle is limited:in the end building bigger blades is less expensive.

 

PierreB

Thanks, Doug, 

I once wanted a supply of liquid air for the cooling of a velomobile.   That market has not developed yet, but the same principle applies to anyone working in hot weather.  A few kilos are enough to supply a trickle of cold, dry air into your clothing for a whole shift, to make work with sun but no wind far easier in many ways.  It can provide clean air for breathing, too, after conditioning.  

http://www.efunda.com/formulae/fluids/venturi_flowmeter.cfm