from CFACT
Author: David Wojik
On July 26, CFACT President Craig Rucker sent a letter to Virginia Governor Glenn Youngkin, warning him of the seriousness of blade failures at giant offshore wind facilities under construction near Virginia. risk. The warning comes in response to a recent blade failure near Nantucket that left fragments of fiberglass scattered on the beach. Virginia is also at risk.
In this article, I'll provide some technical background on this risk. The facility will be one of the largest in the world, with 176 massive turbines. Piling work has just begun, so the turbine blades have not yet been installed. Now is a good time to take a cautious approach.
The Nantucket turbines, manufactured by GE, are the largest turbines operating in the world today, with a power of 13 megawatts, each driven by three huge 107-meter-long blades. For those of us who don't understand the metric system, that number is 351 feet. The Virginia turbine will be larger, with 14 megawatts of power and 108 meters (over 154 feet) long. They are manufactured by Siemens Gamesa (SG).
GE has been producing turbines and blades for two years and has certain operational experience. The SG turbines and blades had just entered production, so there was no experience with them. Suffice it to say they are in beta testing around Virginia.
This novelty is itself a cause for concern. Each blade has three blades, for a staggering total of 528 blades, with a total blade length of over 57,000 meters (187,000 feet or 35 miles). It must have been very dangerous to take the first production blades to such huge lengths.
Multiple and even systemic failures are certainly possible. A sound engineering approach is to build a few and see how they perform over time. Also note that the prototype is located in Europe, so the blades have never been tested in hurricanes, which offshore Virginia is prone to.
Now let's understand a little bit about the physics of blade stress, because it's pretty amazing. SG had a quick look at their website and this is what they had to say:
“The rotational forces found in operating offshore wind turbines place enormous stresses on the blades and the rest of the wind turbine structure. (emphasis added) The tip speed is approximately 90 meters per second – equivalent to 324 kilometers per hour! (201 mph!) – With a projected service life of over 25 years, high quality and innovative design are imperative. With a 108 meter long blade and rotational forces of up to 80 million Newton meters, the stresses on the blade and structure are significant. ! To put it in perspective, when an outstretched arm rotates a 1-kilogram object, the force on a person's shoulder is only about 10 Newton meters!
(80 million Newton meters is approximately 59 million pound feet of torque).
Considering these huge and intense pressures, the novelty of the SG blade becomes even more important.
First, the way they are constructed is unusual. GE and other major manufacturers build the longitudinal blades half at a time and then glue the two halves together. Building a half-pipe is relatively simple and involves lining a trough-shaped mold with fiberglass. Gravity is your friend and checking is easy.
In contrast, SG constructs the entire tubular blade at once. I don't know how, but it can't be simple. Gravity would twist the tubes and inspection must have been difficult. Additionally, while SG manufactures many of its smaller blades in full-tube fashion, their giant blades have different compositions. Because of the extreme pressure, they added carbon fiber.
All in all, we have a new huge blade, subjected to tremendous pressure, made for the first time in an unusual way with new ingredients, and never tested in a hurricane. The high novelty risk faced by Virginia is clear.
But there's another big risk issue, a business issue if you will. SG no longer exists as a company. It was absorbed by its major shareholders to prevent it from going bankrupt. As Reuters put it, the reason was “quality issues and capacity issues that resulted in an annual net loss of 4.6 billion euros ($5 billion).”
In Virginia, we are witnessing the largest expansion of wind turbine production in history, and high quality is critical. People have to doubt whether SG is capable of completing this arduous task at this time, and this doubt indicates huge risks. SG not only has a long history, but is also undergoing restructuring.
Given the novelty of these circumstances, it would certainly be unwise to attempt to throw an untested blade 35 miles without further consideration. So Craig Rooker sent Governor Younkin a letter.
Image Idaho National Laboratory Creative Commons
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