Morten Handberg, Principal Consultant at Wind Power LAB, joins the show to discuss the many variables within wind turbine blades that operators may not be aware of. From design to materials and operation, understanding your blades is crucial to making informed decisions in the field.

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Allen Hall: Morten, welcome back to the program. 

Morten Handberg: Thank you so much, Allen. It’s fantastic to be back. It’s, uh, I really, really happy to be back on the show to discuss blades with you guys. 

Allen Hall: So you’re a resident blade whisperer, and we wanted to talk about the differences between types of blades even within the same manufacturer, because I think there’s a lot of misunderstanding if I buy a specific OEM turbine that I’m getting the same design all the time, or even just the same basic materials are that are used.

That’s not the case anymore. 

Morten Handberg: No, I mean, there’s always been variations. Uh, so the B 90 is a very good example because initially was, was released with, uh, with the, with the glass fiber spark cap. [00:01:00 ] But at later iterations it was, then they then switched it to carbon fiber for, for, for larger, for larger turbines, for higher rated power.

But it, it, but it sort of gave that you were not a hundred percent sure. When you initially looked at it, was this actually a ca a glass fiber, uh, beam or a carbon fiber was only when you started to learn the integral, you know, what, what to read in, in the naming convention that you could understand it.

But it caused a little confusion about, you know, I’m looking at glass fiber blade or, or a carbon fiber blade. So it’s been there for a while, but we’re seeing it more and more pronounced with, um. Uh, OEMs changing to signs, uh, or OEMs merging together, but keeping their integral design for, for, for various purposes.

And then for the, for the, for the people, not in, uh, not in the loop or not looking behind the curtain. They don’t, you don’t know, know, know the difference. So I think it’s really important that we, that we sort of highlight some of those things to make it easier for people to, to, to know, to know this.

Allen Hall: There was a generational change. [00:02:00 ] Uh, even in the 1.5 megawatt class. There were some blades that were fiberglass and then they, there was a trend to move to carbon fiber to make them lighter, but then the designers got better and started putting fiberglass in, where now you have 70 meter blades that are fiberglass worth 35 meter blades, may have had carbon.

Yeah, it’s hard to keep up with it. 

Morten Handberg: You know, it’s really difficult to know. I mean, for, for, for the longer blades, it’s becoming more and more pronounced that they will be, uh, there will be carbon fiber reinforced. But a good, uh, example of where it doesn’t really apply is actually with, uh, with Siemens cesa.

Because if you look at Siemens, Cade said, you know, it’s, it’s Siemens, uh, the original OEM Siemens at the original OEM Cade that merged. Quite a few years back, but you know, we still see the very sharp, uh, difference between the two different designs because whenever you install a Siemens Esso turbine offshore, it’s the Siemens integral blade, it will.

And, and they kept that, [00:03:00 ] uh, and that blade is produced in one cast, it’s called the Integral Blade because that’s their inherited design. And there are no adhesive bond blinds in that. Uh, so all laminated is consolidated. It’s all cast in one go, and then whatever kings and small, uh, defects there, then repaired on factory before they ship offshore.

These are pure glass fiber plate that has not changed at all. So that’s sort of the, uh, how do you say, uh, the one that, that, uh, that is outside the norm that we see today. But the Gaza part of it, they, they’ve kept for onshore purposes, they kept their design using, uh, adhered shells or adhered bond lines.

So they would have two, uh, share webs and then two shells, uh, that are then, that are then, then, uh, glued together, uh, at the bond lines, on the share, on the trading edge, and on the leading edge. With carbon re, re reinforcement. Um, so that is a massive different design within one [00:04:00 ] OEM and often when people say, well, we have a problem with the Siemens commes blade, which one?

Uh, so then it’s very, very important to understand, you know, what blade type, you know, what, what, what turbine model it is because then we can pretty easily drive it, or even for just know the wind farm because. If it’s offshore, we pretty much, you know, we can, we, we know already. We just need to know the what, what, what size of turbine is, and derive what blade type it is.

Onshore becomes a bit more pro problematic because then you need to know, you know, at what, when was it erected, because then, you know, it can be both, but. If you don’t know, then it will just be presented as a Siemens cesa. So it’s really important to keep, uh, in check, uh, when, when, when, when, when looking at that.

So that’s a, so that’s a very important distinction that, that we need, need to understand when the child, when determining blade damages, 

Allen Hall: right, because the type of damage, the integral blade would suffer really completely different than the sort of the ESA bonded design. I was looking at blades in Oklahoma recently that were integral from like a two megawatt machine, and it, it [00:05:00 ] looks completely different when you walk up to that blade.

You can tell that it’s cast in one piece. It’s very interesting to see, but that makes it, I think the, the thing about those blades is that it’s a little more manufacturing cost to, to make ’em that way, but. They are, uh, tend to be a little more rugged out in service, right? 

Morten Handberg: Well, they’re, they’re definitely heavier because of the, the manufacturing process that they go through.

Um, they’re more robust. We, I think we can, we can, we can see that from a track record, uh, in general. Um, but they’re, but the trade off is that they are a lot, they’re heavier. So that means that the, that the components that are used in the Drivetrain Tower Foundation, they’re equally heavier. So you pay the price in the, uh, in the cost of the turbine.

But, uh, overall on the, on the mainland side, we do see less, at least some structural damages and if something really bad happens, so, uh, the trailing edge more often, not it’s kept to the, to the tip or on that part of the trailing edge. So, so, uh, so [00:06:00 ] the, the, the blade structure keeps together better, um, because of this consolidation of the laminates.

Allen Hall: Right, and the, the traditional ESA design, I’ll call it, has been a bonded design for a long time. The issue with bond lines is there is no peel ply stoppage, so there’s no fasteners in it, in case it starts to come apart, it’ll continue to peel, and that’s what we typically call a banana peel when it really goes bad.

The blade splits in two. Once it starts, it really doesn’t have a way to stop. And I think that’s why inspection is so important on those bonded blades. Right? 

Morten Handberg: Yeah. Actually, 1, 1, 1 1, 1, 1 small thing. Uh, peel ply is actually something that’s used in laminate production to, uh, to you apply it when you’re casting, you laminate typically for repair.

Then when you peel it off. The surface is fresh and clean, and then you can, you can continue working it, adding more, more mobilely or, or new coating. So it removes some, uh, lamination or some grinding process that will otherwise be needed, has no structural purpose in it, [00:07:00 ] uh, just to kill that myth of, but you’re right.

Uh, when you have an adhere blade for any, for any manufacturer, for any purpose. If you have a, uh, if you have a deep bonding that starts, then it can, it can, depending on the location, it can grow really fast because you don’t have the same consolidation. You do have some bike layers that would add over, but it doesn’t have the same integral strength that you would see with the, uh, with the consolidated laminate.

Allen Hall: So that’s a big difference. And if you’re looking at blades, and if you haven’t. Looked inside of a hub and looked inside the blade. You, you may not even know. And I think that does happen to a lot of engineers that they, because they, they’re dealing with a thousand blades a lot of times the blade engineers, it’s crazy what they’re asked to go do.

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