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article imageHarnessing the power of the wind — It's all in the blades

By Karen Graham     Apr 3, 2018 in Technology
Since wind and solar power as renewable sources of energy has taken off, wind turbine blades have gotten larger - so much so that the really gargantuan turbines are generally installed in offshore wind farms.
This writer's granddaughter passes a wind farm as she goes back and forth to her college in West Virginia every time she comes home to visit. Catheryne has told me the blades on the turbines are so big. they are actually scary-looking.
But what if the blades were a record-breaking 88.4 meters (290 feet) long - bigger than the wingspan of an Airbus A380? LM Wind Power engineer Lukasz Cejrowski saw the world's largest wind turbine blades installed on a prototype tower in 2016 when he stood in front of the prototype.
How big was the swept area of the blades compared to what we are familiar with? How about the length of two Olympic-sized swimming pools, or the circumference of the Roman Coliseum?
But that 88.4 meters long blade may be small stuff in just a few years because the company's next big project has blades that are 107 meters (351 feet) long.
The scale of these mega wind turbine blades is breathtaking
The scale of these mega wind turbine blades is breathtaking
LM Wind Power
LM Wind Power Reaping the wind
LM Wind Power, headquartered in Lunderskov Municipality, Denmark is now owned by General Electric, however, the company has a long history, dating back to 1940 when they started out as Lunderskov furniture factory, manufacturing wooden furniture.
However, in 1952 the company changed its name to LM Glasfiber as a result of investigating the commercial exploitation of glass fiber technology. It was not until 1978 that the company started making wind turbine blades. To illustrate how wind turbine blades have grown in length over the past several years, in June 2010, LM Wind Power set an aviation record.
The company commissioned the An-225 to carry the world's longest piece of air cargo, as it flew two new 42-meter (138 feet) long wind turbine blades from their factory in Tianjin, China to their test facility in Lunderskov, Denmark.
An - 225 was the largest commercially available aircraft capable of carrying the 42 meter long wind ...
An - 225 was the largest commercially available aircraft capable of carrying the 42 meter long wind turbine blades.
Alex Beltyukov
"Two blades of a windmill 42.1 meters long each were taken from China to Denmark on the order of one of leading freight forwarding and logistics companies Geodis Wilson A/S. While the total weight of the blades does not exceed 15 tons, only the An-225 the cargo compartment of which is 43 meters long, could handle the cargo of such size. It took the Mriya only 12 hours to deliver the blades," the press service said.
Since 1978, the company has been making wind turbine blades, and they have become experts in the field of designing and manufacturing blades no one would have thought possible 40 years ago.
First, they make a glass-fiber and polyester shell for each blade - in two halves. Then the spar cap is added. That's a length of reinforcing material that runs down the inside of each of these halves. For this, the team uses a glass-carbon composite fabric, infused with a special resin that hardens in place.
Fred Olsen Windcarrier s Brave Term  jack-up vessel was used in the construction of the Block Island...
Fred Olsen Windcarrier's Brave Term jack-up vessel was used in the construction of the Block Island Wind Farm.
Fred Olsen Windcarrier
The huge blades go through some rigorous testing, including being buffeted in wind tunnels and going through demanding "fatigue tests" where they are flexed back and forth quickly millions of times to simulate a lifetime of use. They're also tested against a lightning strike.
Why are longer blades better?
With the average-sized horizontal-axis wind turbine, the blades can be anywhere from 20 to 80 meters (66 to 262 feet). The size and height of turbines, however, increase year by year.
Offshore wind turbines are built up to 8MW today and have a blade length up to 80 meters (260 feet). Usual tubular steel towers of multi-megawatt turbines have a height of 70 meters to 120 meters and in extremes, can be up to 160 meters in height.
As a matter of fact, the 8MW record has already been broken by General Electric with the Haliade-X 12 MW, the largest offshore wind turbine in the world to date, featuring a 12 MW capacity. It features a 220-meter (722 feet) rotor, a 107-meter (351 feet) blade designed by LM Wind Power.
The basic parts of a wind turbine.
The basic parts of a wind turbine.
Arcadia Power
Offshore wind farms are being supersized, and this has a lot of advantages. One of the biggest advantages is the location - in the ocean 40 kilometers (25 miles) out, putting them below the horizon due to the curvature of the Earth. This brings us to the size of the turbines.
Most people will say that building an offshore wind farm with many small wind turbines is economically unwise, simply because there will be many more individual bits of equipment needing to be serviced and maintained out at sea, and the sea can be a harsh environment.
And as offshore wind farms continue to multiply, especially in Europe, we will see bigger wind turbines in the future, says Joel Meggelaars at industry association Wind Europe. "The chasing of the big machines will continue only as long as the infrastructure costs are high," he explains.
More about LM Wind Power, GE Renewable Energy, Wind turbines, blade length, projitability
 
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