inventor

Alternative Energy Sources

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Re: wind machines:

The long bladed rotors on the wind-powered electricity generating machines would seem to have a limitation due to the high tip speed limitation and the inefficient use of the available airflow.

The eight blade propellers on the Airbus A400M Airlifter aircraft, on the other hand, would seem to make better use of the column of air due to the greater number of blades. The longer chord on the blade wings would also increase efficiency, and the tip speed may be greater due to the more sophisticated aerodynamic design for the blade wings. The smaller diameter swept by the A400M props would permit higher prop RPMs and less drag at all speeds.

With eight blades a wind machine driving a larger single generator on a single stand and single electrical system connection could produce electricity more economically due to a more efficient use of investment capital.

Would Airbus lend a prop and bearing pitch control setup to a wind machine maker with an interest in licensing the use of the technology?

The appearance of the curvy eight-blade A400M props is also far better than the sword-like long three-blade props of the current wind machines.

Ideas?

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There's a few thousand wind turbine companies in existence, and a few more thousand scientists working on wind turbines in universities, it's the flavour du jour. I highly doubt that they wouldn't have recognized such a superior design and commercialized it, if it was superior, especially since turboprop blades are designed for spinning at a very high speed and high angle of attack to generate thrust at high air speeds.

Here's an example of a much more innovative approach in wind turbine design: 125042938409762.jpg

The problem with wind generation, ultimately, is that there's actually very little wind and a lot of power required. The next century of energy will be dominated by coal, nuclear (small pebble-bed reactors especially), and to a lesser extent, geothermal power (once dry rock projects become scientifically feasible, which should take a decade or so) and diverting rivers. This according to a fairly conservative bunch of guys who don't buy the green hype.

I've talked to a very competent oil investor (and former oil engineer) who believes we haven't even seen peak oil yet, and are unlikely to do so for quite some time, as technological advances are improving faster than reserves or new regulation can keep the price of oil up. He's basing his valuations on $45 oil (and only because of relatively high inflation) - that is, a company that cannot be reliably profitable and with strong free cash flow at that price should not be invested in.

An interesting side effect of Obama's "boot on the neck" of BP is that he is effectively killing permits for all junior exploration companies (as compliance becomes too expensive), handing over to the majors the very welcome bonus of an oligopoly over offshore projects.

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The problem with wind generation, ultimately, is that there's actually very little wind and a lot of power required. The next century of energy will be dominated by coal, nuclear (small pebble-bed reactors especially), and to a lesser extent, geothermal power (once dry rock projects become scientifically feasible, which should take a decade or so) and diverting rivers. This according to a fairly conservative bunch of guys who don't buy the green hype.

An interesting side effect of Obama's "boot on the neck" of BP is that he is effectively killing permits for all junior exploration companies (as compliance becomes too expensive), handing over to the majors the very welcome bonus of an oligopoly over offshore projects.

2 very excellent points.

1) Wind is practical for individual users or direct industry/farm use, as one can switch over from short-term available wind power to on-demand utility power at the flip of a switch. But it's very definitely impractical and inherently disruptive at the utility level and above. On the Columbia River System, in the Pacific Northwest, power is routinely forecasted from hourly out to 20 years with a fair degree of accuracy. Wind can only be forecasted in sub-hourly increments with any semblance of reliability and, therefore, planning is difficult if not impossible. More often than it supplements the system, it overloads it in short-term surges, which require intervention to take the power offline, or other power on the system, in order to prevent transmission line overloads and faults that could bring parts of the system down. It is a net liability. If it weren't for the subsidies and other incentivizing, the PR cachet, and the enviro-grandstanding of heads of federal agencies and utilities, it would not be any part of large-scale power production and distribution at all.

2) The Obama "boot on the neck" certainly will do what it has done to the Financial industry: Bring the largest producers under the foot of the State and kill small business competitors. So has the suspension of new drilling permits for years. Those who didn't get in the door will find it much more difficult now. Non-major energy players can still get in on the action in a financial sense, of course: Most wells are owned by partnerships. Jack #2 was drilled by Devon Energy but they only had a ca. 20% stake. There are active partners and limited partners and investors can still invest even if new companies can't drill. But the market for such arrangement goes down drastically when the gov't requires additional impact reports, taxes, regulatory barriers, or just plain time to get to the return on investment. And I can't imagine a more oppressive stance than Obama has taken.

Every statement, every action of Obama's has been to threaten punishment and heavier regulation and fines and taxes, yet, were he to do none of that in the name of the Federal gov't, the affected parties in the gulf, through class action, could recover for their objective damages. The tourism industry has a bigger problem, in that it is harder to point to receipts not earned, when direct damage has not occurred, but potential tourists avoid rumor-tainted areas like the Florida coast. But this is what the courts are for. What Obama will do is to destroy or cripple BP, sack their treasury for more of his own spending projects, and leave those injured no one to collect from, except the Federal gov't, which suits Obama just fine.

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I do some siting and evaluation for wind power. Few locations have enough wind resource to give a payback that's shorter than the life of the equipment. The difference, in many cases, is made up with utility incentives. I'm working on a site right now that will have a 7-year payback, which is very good.

Longer airfoil chord is not associated with higher effeciency. Higher aspect ratio (span/chord) is. Variable pitch has been incorporated into some wind turbines. The first 10 years of my career was spent in aircraft design and analysis - albeit mostly structural, so the transition to wind power was fairly smooth.

There still is some very good untapped wind resource in the United States. By "good" I mean that the site is good in terms of pure resource, wildlife, visual impact, etc. Solar and solar thermal is fairly untapped and will experience steady growth in the U.S. I'm starting to evaluate some propane-heated remote sites for solar thermal and it looks pretty good (in California).

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I do some siting and evaluation for wind power. Few locations have enough wind resource to give a payback that's shorter than the life of the equipment. The difference, in many cases, is made up with utility incentives. I'm working on a site right now that will have a 7-year payback, which is very good.

[...]

Longer airfoil chord is not associated with higher effeciency. Higher aspect ratio (span/chord) is.

I want to argue two definitions: wing aspect ratio and airfoil aspect ratio.

Read the news item in the link I posted. Spain gets a huge percentage of its generated electricity from wind turbines.

An aircraft's wingspan is measured from wing tip to wing tip. The aspect ratio of the wing is:

"

Aspect ratio (wing)

From Wikipedia, the free encyclopedia

[...]

In aerodynamics, the aspect ratio of a wing is the length of the wing compared with the breadth (chord) of the wing. A high aspect ratio indicates long, narrow wings, whereas a low aspect ratio indicates short, stubby wings. [1]

For most wings, the length of the chord varies along the wing so the aspect ratio AR is defined as the square of the wingspan divided by the area of the wing planform.[2][3]

AR = {b^2 \over S}

where

b is the wingspan, and

S is the area of the wing planform.

"

However, I was referring to the aspect ratio of the airfoil, and that means the airfoil chord is longer in a ratio to the height or the camber of the airfoil section measured at right angles to the chord.

The higher the aspect ratio of the airfoil means there is a lower aspect ratio of the wing. Different contexts.

The propeller solid disk term refers to the area presented to the cylinder of air through which the propeller travels. Increasing the solid disk is accomplished by increasing the wing chord (practically the same as the airfoil chord depending on how it is measured) or increasing the number of propeller blades.

Scientific experimentation would provide the answers regarding the ratio of energy produced by this or that propeller in given conditions to the amount of physical structure involved. That is, in entrepreneurial terms, the cost of production to sales cost ratio.

My guess is that current wind turbines are in an early stage of development.

I guess that the sailplane wing that is configured with different angles of attack and different NACA airfoil design sections at selected distances from the hub is the order of the day for wind turbines. A sailplane wing has a high wing aspect ratio, e.g., a long narrow wing. In the currently popular wind turbine designs the tip speed is getting to be a problem in high winds, and variable pitch designs are being tried. The wind turbine designers, I believe will try to decrease the disk diameter with variable pitch blades, while increasing the percentage of solidity of the propeller disk. They will increase the airfoil chord slightly and, also, add blades to do that.

Wind turbine designers will curve the blades to design better stall characteristics and to provide better blade tip turbulence characteristics for lowered drag. Sailplanes are now adding NASA (not NACA) winglets, and curved wing leading and trailing edges are being designed for better stall transition characteristics. See the Polish sailplane designs called the Diana1 and Diana2 to see the changes due to the new and curvier technology.

http://www.dianasailplanes.com/

http://www.dianasailplanes.com/szd55.html

http://www.dianasailplanes.com/Diana%202%2...0ground%201.jpg

Technology is changing the industry. Quoting from the Diana2 website:

"

The available surface loading could be increased twofold from 28 to 58 kg/m2 (5,73 -11,85 lb/ft2 ), while the ballast in wings surpasses the glider empty weight by 60 kg (132,28 lb) – not to be found in any other design.

"

The propellers on the Airbus A400M aircraft have curved edges, and it may be that a blade with curved leading and trailing edges and, also, integrated curved winglets, or even with no winglets is in the cards for wind turbines.

I guess that future wind turbines will be designed with 8 to 12 curved blades, and the aerodynamic efficiency will markedly increase from the current designs. With stronger new materials the new wind turbine designs may actually be larger, and they will automatically pivot to point into the wind. The designs will be architecturally sleek, curvy, and inobtrusive.

I am a CAD engineering designer: manufactured products, civil, structural, architectural, and I use 64bit MicroStation V8i on Vista. Let me quote on some CAD work for you.

Inventor

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I do some siting and evaluation for wind power. Few locations have enough wind resource to give a payback that's shorter than the life of the equipment. The difference, in many cases, is made up with utility incentives. I'm working on a site right now that will have a 7-year payback, which is very good.

[...]

Longer airfoil chord is not associated with higher effeciency. Higher aspect ratio (span/chord) is.

I want to argue two definitions: wing aspect ratio and airfoil aspect ratio.

What for? You incorrectly stated that shorter blades are categorically more efficient.

Read the news item in the link I posted. Spain gets a huge percentage of its generated electricity from wind turbines.

Viro claims about an industrial backward country using uneconomically expensive, subsidized politically correct windmills during a gust over the weekend have nothing to do with aspect ratio or airfoil design or much of anything else that matters. As others have written, experience -- understood in terms of engineering principles -- shows the severe limitations on using wind power in a large scale power distribution network. One of them is the critical issue of stability and control of the system.

Scientific experimentation would provide the answers regarding the ratio of energy produced by this or that propeller in given conditions to the amount of physical structure involved. That is, in entrepreneurial terms, the cost of production to sales cost ratio.

That has been done for many, many years.

My guess is that current wind turbines are in an early stage of development.

Early with respect to what and what is the point of posting uninformed guesses? Regardless of what future developments and refinements may evolve in the future, airfoil design in all kinds of turbomachinery operating under different design and off-design point conditions has been developed over many decades.

I guess that the sailplane wing that is configured with different angles of attack and different NACA airfoil design sections at selected distances from the hub is the order of the day for wind turbines.

A sailplane wing has a high wing aspect ratio, e.g., a long narrow wing. In the currently popular wind turbine designs the tip speed is getting to be a problem in high winds, and variable pitch designs are being tried. The wind turbine designers, I believe will try to decrease the disk diameter with variable pitch blades, while increasing the percentage of solidity of the propeller disk. They will increase the airfoil chord slightly and, also, add blades to do that. Wind turbine designers will curve the blades to design better stall characteristics and to provide better blade tip turbulence characteristics for lowered drag. Sailplanes are now adding NASA (not NACA) winglets, and curved wing leading and trailing edges are being designed for better stall transition characteristics. See the Polish sailplane designs called the Diana1 and Diana2 to see the changes due to the new and curvier technology.

On what basis do you make such guesses and what is the point? Why would anyone restrict designs to NACA profiles classified well over a half century ago before computer analysis technology for prediction and measurement? Sail planes have nothing to do with it -- you can't just look at the esthetics of some kind of airplane that visually stands out and jump to conclusions about engineering design in different realms without regard to engineering experience and actual analysis.

... The available surface loading could be increased twofold from 28 to 58 kg/m2 (5,73 -11,85 lb/ft2 ), while the ballast in wings surpasses the glider empty weight by 60 kg (132,28 lb) – not to be found in any other design.

"

The propellers on the Airbus A400M aircraft have curved edges, and it may be that a blade with curved leading and trailing edges and, also, integrated curved winglets, or even with no winglets is in the cards for wind turbines.

What are you betting for and what is the point of equating aircraft with turbomachinery? Complex computer programs are used to design and analyze airfoil performance with all kinds of geometric and flow conditions under the relevant conditions of the application, taking into account many more factors than you can imagine. This is a very complex field of knowledge and practice. Engineering of structures in fluid flows does not follow esthetic preference for shapes and talking off the top of your head. It requires a lot of complex mathematical analysis and experiment in combination.

I guess that future wind turbines will be designed with 8 to 12 curved blades, and the aerodynamic efficiency will markedly increase from the current designs. With stronger new materials the new wind turbine designs may actually be larger, and they will automatically pivot to point into the wind. The designs will be architecturally sleek, curvy, and inobtrusive.

Guessing the number of blades along with esthetic issues of "sleekness", "curvy" and "inobtrusive" are not design parameters for airfoil performance. Those who know what they are doing in the physics, engineering and mathematics determine appropriate geometry of the blades for different purposes.

I am a CAD engineering designer: manufactured products, civil, structural, architectural, and I use 64bit MicroStation V8i on Vista. Let me quote on some CAD work for you.

Being a draftsman on a PC does not imply expertise in engineering qualified to design and analyze airfoil performance in accordance with sophisticated engineering and physical principals of aerodynamics and the requisite mathematics used in the advanced computational computer codes. If you are interested in this field there is a lot you could be reading in fluid dynamics, turbomachinery and specialty applications. It is a fascinating field, but speculation and guesses from pictures of airplanes and a little technical terminology to throw around from a few scattered pages on Wikipedia will not help you understand it and is not informative on the Forum. What background do you have in fundamental fluid dynamics?

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Thanks, ewv. I was planning to post the same sort of reply at some point when I had time.

"inventor", you have now started two threads on subjects that I happen to know a bit about (underwater vehicles more than wind turbines, but I'll reply in this thread). Frankly, you are guessing at both the principles involved and the state of the current technology.

Others things to note: from my understanding, it is the interaction of a *field* of wind turbines that really affects how efficient they are. The first row of turbines generate significantly more energy than subsequent ones because the wake from the first row significantly decreases subsequent turbine efficiency. This makes analysis very, very difficult. A picture:

pichugina480.jpg

Note also that some wind turbines already do pivot to point towards the wind; I'm not sure why you think they don't.

Another *green* energy source that is starting to be used is "water turbines" to harness tidal energy, particularly in fjords and channels. One was just installed in New York City's East River by Verdant Power. The fact is, these turbines look nothing like a ship's propeller because they have a significantly different purpose! While I'm not intimately familiar with aerospace technology, I suspect the same idea is true of wind turbines and airplane propellers. I haven't studied it too much, but I'd guess this is because turbines (both wind and water) move at a much lower speed than a propeller and have a completely different purpose.

But in the end, none of this really matters because wind and water turbine power is a viro fad that is not sustainable. Estimates I've heard say 80% of the Earth's oil has yet to be undiscovered. And if you really don't want to use oil, nuclear energy is far more feasible than wind turbines. What we really need are mathematically-formulated, well-crafted engineering solutions to the difficult problems.

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Estimates I've heard say 80% of the Earth's oil has yet to be undiscovered.

To be more precise, oil companies discover enough oil for 30 years of production taking into account productivity improvements and the forward market (i.e. how much we'll need to pull out of the ground in the future). That is in part why we'll always "run out of oil in 30 years". For a lot of lefties, everything should be frozen in place, so obviously no new exploration will take place... great reasoning, no?

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"The longer chord on the blade wings would also increase efficiency..." - Perhaps I misunderstood. But, I agree with your use and definition of higher "aspect ratio" of airfoil, for the most part. Aerodynamics is very fun work. I added a year of aeronautical engineering to my mechanical studies in school. I've often marveled at the very high effeciency aeronautical bodies that have a length/thickness ratio of 3:1 (pretty fat!). The Questair Venture is a great example of this. It looks like an egg but flat runs away from the competition. As you thin out structures from there, flutter may rear its ugly head. Fun stuff. Tough to make good paychecks with it...

One buggaboo with "green" energy souces is politics. Discussions of it almost always include skewed viewpoints that stray from the facts of the resource and site and return to people's feelings. If you have good resource, the equipment delivers a high level of reliability confidence, you can maintain it, and your payback beats the life of the equipment...look into it (wind or solar). In some cases it financially makes sense. I've got one site right now that's perfect. There aren't even any neighbors within sight of the location who could complain of visual impact, and there probably won't be for well beyond the life of the equipment. This is the site with a 7-year payback - a real wind tunnel. I analyze the science and equipment, report my findings, then sit back and let people decide how they feel about the project (knowing that may be what kills it).

Today - I'm looking into direct digital controls for future solar-thermal designs. I enjoy my work.

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I was watching post-WW1, pre-WW2, Nazi propaganda newsreels on YouTube.com, and it was explained that the Nazis were training future German sport aircraft pilots on sail planes.

The sailplane wing designs included winglets. Apparently, the sailplane designers were experimenting with so-called infinite wings, although at that time they may not have discovered the complex wing flow paths that they realized a few years later on integrated wing-body swept-wing war aircraft designs.

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