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Siemens unveils world's largest wind turbine blades


August 3, 2012

A Siemens B75 blade in its mold

A Siemens B75 blade in its mold

Image Gallery (5 images)

Siemens has released pictures of its truly gargantuan B75 wind turbine rotor blades. As you might imagine, the prototype turbines that will use these blades boast some staggering statistics of their own (Airbuses at the ready, please).

Remarkably, the 75-meter-long (246-ft) blades consist of a single component made from epoxy resin and balsa reinforced with glass fiber, cast in a gigantic mold using a process Siemens has cunningly named IntegralBlade.

Initially, three B75 blades will be put to use in a prototype 6-MW offshore turbine at Denmark's national test center at Østerild. The sweep of the completed turbine will cover 18,600 sq m (200,200 sq ft) and the tips of the blades will move at 290 km/h (180 mph) at full lick. At a wind speed of 10 m/s (19.4 knots), the turbine will be hit by 200 tons (181 metric tonnes) of air every second.

The blade length of 75 m is not a kick-in-the-pants off the wingspan of an Airbus A380 (at 79.75 m or 261.6 ft), meaning that in a Y-position, the airliner could easily pass within the 154-meter (505-ft) sweep's radius above the blades (spatially at least. In practice this isn't recommended).

Siemens has already seen 6-MW turbines installed at the UK's Gunfleet Sands wind farm, albeit with 60-m (197-ft) blades. Thanks to a process Siemens has branded "QuantumBlade," it claims the B75s weigh four fifths of conventional blades. "The weight reduction is achieved by using specially designed blade profiles that are also shaped in a way that delivers maximum rotor performance at a range of different wind speeds," the company says.

Source: Siemens, via Wired UK

About the Author
James Holloway James lives in East London where he punctuates endless tea drinking with freelance writing and meteorological angst. Unlocking Every Extend Extra Extreme’s “Master of Extreme” achievement was the fourth proudest moment of his life. All articles by James Holloway

Good Gawd, that is impressive, incredible actually

Bill Bennett

It is so impressive that one can't help wondering how it is transported to the installation site.

Nantha Nithiahnanthan

At this point I am not convinced that longer is better in wind mill blade design. I think that a shorter blade with a greater chord length (distance from leading to trailing edge of the blade) would work better. The shorter blades would have a higher RPM at the same blade tip speed which reduces the step up the transmission has to make to get an efficient speed for the generator. It could make the windmill blades look more like shovels than sword blades though. I'd keep the greater tower height for the smoother air and greater wind speed.


Why is this something to brag about? One of the main problems with wind turbines is their sheer size and presence on the visual landscape, not to mention the noise from such large blades cutting the air.

You can call these monsters "green" but they blatantly industrialize any landscape they're installed on, and we're running out of areas that won't be affected by their blight. They should be working to make wind turbines smaller, if anything. When they reached 400 feet enough was enough!

Alec Sevins

re; Nantha Kumar Nithiahnanthan

They use a really long trailer with steering and a driver at both ends and presumably blocker vehicles to open space for lane changes and cornering. The special permitting process probably adds several thousand $ to the cost of the windmills. Hopefully the factory is near the relevant docks given that the windmills are designed for open water.


From what is not mentioned: noise is the same frequency & loudness? Later studies show that these turbines cannot be spaced as close as smaller turbines. As to blight on the visual landscape: are they better for off-shore sites - fewer transporting for installation, noise & ugliness for landviewers, etc.

Greg Zeng

re; Alec Sevins

I think the wind to electricity concept is flawed because of the inefficiency of electrical storage, and the constant variation in wind speed changes the output of the windmill on a second by second basis ignoring power usage. I would like to see windmills compress air or lift water and generate the electricity from the stored energy on an demand basis. Personally I would prefer a few gigawatt nuclear power stations built on ships operated over deep water but the actual footprint of wind is tiny and the effect on the surrounding environment is even less. Bigger windmills make for less footprint per megawatt.

If you stop throwing a tissy fit every time you see a windmill you will find that they bother you less and less. Actually that is true about just about everything and I need to follow my advice more myself. Just imagine the windmills hidden behind a cloud of smoke.


Why do these windmills always have 3 blades and not some other number? There is a lot of empty space between the 3 that could be producing more power, why not use it especially given the cost of the central support tower? Jet engines for example have hundreds of blades. I would love to see the cost-benefit breakdown that proves 3 is the ideal number.


re; Grunchy

Three blades are easy to balance and for generating electricity the higher the RPM the better and fewer blades supports a higher RPM while removing the same amount of the energy from the wind as more blades moving at a lower RPM. I think that with the RPM being limited by blade tip speed that going to four blades might be an improvement but my brother an electrical engineer at a windmill manufacturing company disagrees and I certainly do not have the proof. And with people like Island Architect beating Bill Allison's dead horse just about every chance he gets makes it less likely that a four blade design would even get computer analyzation time.


Grunchy, its simple geometry. 3 blades will always be balanced giving a much smoother power-production. Also, more blades would mean each blade would be passing into the turbulent air created by the previous one. So more blades, would need smaller blades, which would be less efficient. You would hope the designers ended up with 3 from optimizing blade design vs number of blades. A major problem with bigger blades is the tip speed exceeding mach1.0

As for installation, they'll be produced at a factory on a quayside, loaded straight onto barges and towed out to sea.


Everyone's argument AGAINST windpower is aesthetic-based. It's my opinion that when i see a field of these spinning in the wind it's somewhat beautiful, almost an accessory to nature, so you can appreciate the wind without seeing it. How many kids, bicycles, yards, etc. have pinwheels on them?

They look better than : oil rigs, natural gas stations, power stations, pipelines, NUCLEAR PLANTS, smokey COAL BURNING power plants and they're not polluting. People go to take tours and see Dams only after forgetting about the huge ecosystem they drowned to build it. I'd volunteer to have one in my yard except it would cut down all the ugly power lines.

This is just my opinion.


Here's a simple question: what happens to all the air that passes STRAIGHT THROUGH the huge areas in between the blades? Does anybody seriously believe that that air somehow helps the blades turn - the majority of it? The larger the wind turbine, the more of this air is wasted - if the turbine has only three blades. The angular velocity decreases the larger the turbine is (correct me if I'm wrong), in other words the RPM is lower, and a huge amount of the wind passing through the swept area of this turbine will NOT affect the blades in any way.


I forgot to mention, ALL that matters is the cost per kilowatt hour. What is the cost per kilowatt hour, UNSUBSIDISED, for this turbine?


hey packoftwenty. Find out what solidity means and note that the value exceeds 100% near the blade's root. that is to say, those three blades actually overlap near the turbine's hub. then find out what laminar flow means, then post your questions.


Oh dear - looks like I've upset 'nutcase' again, by asking awkward questions...

So does most of the air NOT pass through the HUGE gaps in between the blades, unaffected? How is that possible? How do the blades affect wind which never has touched them, and never will touch them, because it's 50 METRES away from them. (You know, in that HUGE gap in between the blades...)

Did you look up density of air and viscosity of air while you were looking up laminar flow? LOL...

So let's imagine the wind turbine was TEN TIMES this size, and still only had three blades. 1,540m in diameter. Are you seriously trying to tell us that MOST of the air passing through the swept area is somehow going to affect the blades, and help turn them?

Why do wind turbines have slower RPM, the larger you make them? Do you understand what you're talking about, 'nutcase'? LOL.

Just to spell it out for you: imagine a flock of birds flying through the swept area of this turbine - a huge, dense flock of them. How many would get through unscathed? The vast majority, because the vast majority of them would not be where the blades are, at any given moment.

Pray explain to us all how the MAJORITY of the wind going through those huge gaps can help turn the blades, and by how much...


ps I forgot to ask - how much is the subsidy going to be for this wind turbine, in order to con the public into believing that the electricity it produces is viable? LOL...

Read the book "The wind farm scam" by John Etherington.


Why not install solar panels at the base of the platform. A strong and expensive platform is built, the solar panel platform would be below the blades and have a diameter the same as the blades. And of course useful for when there is no wind.

Dawar Saify
packof twenty, your question about what happens to the wind that "...passes straight through" the rotor blades is interesting, but unless all turbines in the array are of identical dameter, pitch, style and placed one directly in front of the other, the wasted source energy (the wind) can be held to a bare minimum. through proper design and placement. EVERY device designed to convert one form of energy to another has parasitic losses. whether it be friction in the rotor shaft bearings, eddy currents that are created as the wind passes through the rotor or using fixed pitch rotor blades that can not be adjusted to capture the most energy possible from the range of windspeeds that were reported in the engineerng site study. If wind speed is higher tthan design specs, the rotor blades are feathered (let more air pass through to prevent equipment damage), then the same technology cann be used to optomize the rotor blades pitch in actual operation - with safeguards, of course. NK Fro

I'm glad it was only mentioned once in these comments, but I feel I should say something to negate the misconception that these things produce sound.

I'm thinking that the most common relation people can make to a turbine upon the sight of them is their common household fan. Fans make tons of noise so surely this thing would too. The opposite is true, because it is air turning the blades, powering a turbine.

The sound coming off the blades is so faint it's indiscernible.

I know this because the area between Lafayette, Indiana and Chicago Illinois has a large wind farm and you get as close to them as you want if you're willing to take a country road or two and drive down some gravel. One is right next to a gas station by the interstate. If you've lived in or near a city, or the suburbs, you're dealing with noise levels far beyond what these things were engineered to keep to a minimum.

If you want more proof, listen to this. http://www.youtube.com/watch?v=VPBeV1m5SlQ

Also, from driving that stretch many times, those windmills are absolutely beautiful in action.

it tastes like burning

The relative lack of of noise you mention is not universal. While the relative silence may be attractive, it may not be required for all sites or the engineering/manufacturing maybe so costly that it is not a realistic expectation.

NK Fro

Are some people saying the space between blades is 'wasted' by not hitting blades? first, if you use all the movement of all the air, you stop the air, so you can't take away 100% of the energy. hence the maximum efficiency of wind turbines. the air that 'gets through' without being affected by a blade is actually affected by turbulence of the other blades, and air that is slowed down affects air not slowed by the blade. I don't understand why 3 is more efficient, but assuming they have been testing these for many man years, they must have found 3 to be optimum. and larger blades may have more space between them at the tip, but if they stick with 3 blades then I assume it is the relative spacing & the degrees arc, not absolute spacing that matters. [distance between tips vs blade length] I'm not a physicist of course but have heard it explained enough while researching small wind generators.

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