Show notes
Wind Power LAB's blade expert Morten Handberg explains a critical wind industry problem: new turbine blades are failing years too early. These massive blades - now stretching over 100 meters - are experiencing unexpected structural damage due to complex aerodynamic forces. Handberg shares Wind Power LAB's essential strategies for detecting and preventing these costly blade failures before they shut down your turbines.
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Allen Hall: As wind turbines reach unprecedented heights and blade lengths stretch beyond 100 meters, unexpected challenges are emerging from the field. This week we welcome back Morten Handberg. The renowned Blade Whisperer from Wind Power LAB. In this eye-opening discussion, Morten reveals why modern blade designs are showing structural issues earlier than expected and what operators need to watch for to protect their turbines.
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Welcome to Uptime Spotlight, shining Light on Wind Energy's brightest innovators. This is the Progress Powering tomorrow.
Allen Hall: Morten, welcome back to the show.
Morten Handberg: Thanks, Allen. It's great to be, be back again.
Allen Hall: You are one of our most popular guests. You are the Blade Whisperer. And any time I'm at a trade show, people ask, how's Morten doing? How's the Blade Whisperer doing? Like, well, Morten's great. Morten's super busy, but Morten is great.
And they want to have you back on. So here we are. We're back on again. And. The topic of today's discussion is about aerodynamic stresses that happen to blades, and we're seeing more problems with that than some of the quality issues. I think it's a combination of quality and aerodynamic issues. What is happening in the field right now with aerodynamic loading on some of these new, longer, more flexible blades?
Morten Handberg: Well, it's, it's something that's been been happening over time. So if we look 10, 15 years back, then the blades were of course shorter. The and they were a lot stiffer than they were today. They were heavily reinforced and you could say maybe they were. They were under optimized that they had a lot more load capacity and that were then what they needed.
And, and in, in process of the, in, in, as the blades have been become longer than the, then that buffer have gone away, so, because the, in order to build a logger blade, you had to reduce the the, the thickness of your laminates to avoid an overly, you know, bulky structure, but something that could harness the wind in a more efficient way So that leads to slender, thinner blades that are a lot softer.
And we can see that in the natural frequency that the, that the flap wise and edge wise frequencies, they have kind of gone down. And that's because the blades become softer. And that also means that the way that the blade behaves with the wind direction means that the gravity loads are still a major, a major component, but Aeroelastic loading, which adds to shear and torsion loads, have become much more prominent loading conditions on the blades that we see today.
Allen Hall: That's interesting. Yeah, obviously the blades are lighter than they ever been for the length. I remember being at DTU a year or so ago and looking at one of the first offshore wind blades that Vestas had made, and it was beautiful. back into DTU's laboratory being examined. And that blade was so stiff and so overdesigned that it could have lasted, it had, it could last another 20 years.
It had been out in service for 20 years. It could have lasted easily another 20, maybe another 30 years because of the way it was designed, how stiff it was, how short it was. It was like a 20 meter blade. It wasn't that big. But today when we're talking 60, 80, 100 meters, those blades are just Dynamically different.
Is it a combination of just trying to lower the cost of the blade or just the mere fact that the weight is so high? We're trying to transport it. What's driving down the margins here in terms of the blade design and making them a lot more flexible?
Morten Handberg: Well, it is, it is an effective of well, by increasing the length, you also increases the power that you can harness from the blade.
You know, that so, so it is a, it is a desire to create larger turbines and one of the. Easiest ways to do that is simply by making the blade longer because you have to, it, you can do it. It's, it's compared to increasing the sweat barrier or optimizing. And in other ways, it is a, it is a low hanging fruit and by lowering the rate of the blades, you can also live with a lighter drive train, less steel in the tower, smaller foundation.
So all of these things play in into why that the blade is such a, so much in focus in terms of. Driving down cost overall is by reducing the the weight of the blades. And that comes as a consequence of it being more it, yeah, it has, has less design buffer and it also will have less lifetime compared to the, to the more conservative blades that we've seen before.
You can say that, you know, some of the two megawatt turbines, I wouldn't be surprised if you can from a blade perspective that you can, you know elongate the lifetime to 30, 40 years, because they're, they're so conservatively designed compared to what we see today.
Allen Hall: Okay, so adding a kilogram to a blade has consequences all the way down to the foundation, which makes sense when you say it.
Okay, so that just adds cost and complexity to every other component in that wind turbine. So the drive then is to lighten the blades and also lengthen the blades at the same time. Now, when we do that, I, as I talk to operators around the world, they come back and say to me, okay, yeah, sure we're using longer blades, of course it creates more power, but they're all being qualified.
They're all being tested, right? So we shouldn't have anything to worry about what they're in service. Has the test standards kept up with the rapid design changes that have been made? Not at all.
Morten Handberg: As I said before, you know, gravity loads was the predominant load on all the blades. And that was also what did.
Testing and certification standards focused on. And that's still what it's, what's being, being done today. There are, you know more being done on hybrid loading, combining stepwise and edgewise, but that's still gravity based loads. We're not taking into account aeroelastic loads when, when, when testing and certifying, but that's all only done in simulation.
And then we learn about what have, what's happening in, in operation. In operation. So. So the testing and certification has not kept up with the with, with the load conditions that are, that, that, that we see on, on the modern blade.
Allen Hall: So I have a existing OEM that I like using, and I just want to go to the next generation of wind turbines, which is what is happening today.
That design of that new wind turbine may not have the same robustness as the one you are used to using, particularly if you'd let 5, 10 years go by. And so then if you're thinking about the blade design, you're trying to evaluate blade design, you really don't have the data in front of you then. If they haven't tested that for torsional loading, aero loading effects, you really don't know what the history of that blade will be.
Just because you don't have the data, right? You
Morten Handberg: have no idea what the, what the fatigue lifetime is from these new combined loads and, and we are seeing, you know blades, structural blade damages, blade failures happening on, on wind farms. From a variety of wind turbine types, where there is no, no, no sign of manufacturing defects, there is no lightning strike, there is no sign of transport damage or failed repair.
So, you know, it's very difficult to prove exactly what kind of load it is without having the exact model or having other kinds of other types of data. But, you know, When leaving everything out, then you are starting to think about, is there something, some load condition going on here since we're seeing these buckling related failures in areas where they, the blade simply shouldn't shouldn't have any kind of structural damage.
We're seeing a lot on On on shell sandwich panels where we, where we see deformation the damage and related to deformation defects. And very early on, actually, you know the blades are designed for 25 years, but in a wind farm, we can see, you know, multiple blades with long transverse cracks over the, over the, the, the shell panels, and there's nothing to suggest any kind of manufacturing issue.
otherwise that would have allowed for this defect to develop. And that's again, one of the, one of the things that I think we need, we need to be mindful of with these new, new turbines. So how prevalent is this issue? What should I be looking for in the field? The need for inspection. We've been saying this for many years, also for the older blades, but it's, Absolutely equally true.
So you need to do, at least yearly inspection, maybe in the early years, do it a bit more often, you know, and do both internal and external because whatever you see on the outside, on the outside will likely have started on the inside.