Show notes
Allen Hall and Joel Saxum discuss the critical issue of failed blade bolt inserts with Edo Kuipers of We4Ce. Edo explains the problem, its widespread impact on the wind energy sector, and introduces We4Ce's innovative solution - an upgraded blade bolt insert that can be retrofitted in the field, potentially saving operators significant downtime and repair costs.
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Allen Hall: Welcome to the Uptime Wind Energy Podcast. I'm your host, Allen Hall, along with my co host, Joel Saxum. On this episode, we're addressing a critical issue that is plaguing the wind energy sector, the problem of failed blade bolt inserts in wind turbine blades. And these failures have a significant concern for wind energy operators, leading to downtime, costly repairs, and the potential for liberated blades.
Our guest is Edo Kuipers, owner and engineering manager of We4Ce. And We4Ce is based in the Netherlands. We foresee offers a range of services related to the design and engineering of wind turbine rotor blades. And they have designed an upgraded blade bolt insert that can be retrofitted in the field. And this new insert product could dramatically lower a wind turbine operator's downtime and blade repair costs.
Edo, welcome to the show.
Edo Kuipers: Thanks for having me here, Allen and Joel.
Allen Hall: So this is a really interesting product, but I first, I want to get to how big of a problem do we have in the industry? And Joel and I have been traveling around the United States quite a bit. And pretty much every farm we stopped at had blade bolt insert issues.
They didn't know why they were having them, but they had them and they were deeply concerned about it because of what could happen to the turban. And Edo, are you seeing the same thing? Are you getting a lot of reach out that way?
Edo Kuipers: Yeah, more and more we see this. I think in 2021, we were contacted by the Indian market for the first time.
Those were 40 meter long blades, 1. 5 megawatt platform. And those blades were like 13 years on the turbine. And then all suddenly started flying off basically. And more and more recently, this is popping up basically not after 13 years, but after six years, for example, already on a 2. x platform. So yeah, we have been contacted first on the Indian side.
We have seen it in Brazil. We have seen it in Thailand, for example, also. So it's more and more addressing the problem. Also from the Northern America, we have the first context.
Joel Saxum: So I think that if we describe basically the breadth of the problem so there's the, when you bolt the blades on, and if you're in a, if you're a wind technician, this stuff, right?
You've seen it, you've done it. You've been around these things. For some people that are, yeah, some people that aren't as technician minded, you may not know exactly what the problem is, but what it is basically when you bolt the blades onto the hub, there's all these studs, right? And the studs come through, or the studs stick out, you stick it into the receptor on the basically on the hub, and then you bolt 'em on.
But if the, where the stud connects into the blade. It doesn't stay true to its design and becomes loose, it starts to move, then however it's bolted doesn't matter at all.
Edo Kuipers: Correct. Also, it's not a bolt problem, it's the connection between the steel bushing itself. This is like a plug in the wall when you hang up a painting, for example.
This plug in the wall is getting loose from the laminate.
Allen Hall: All right. So if the inserts are becoming loose. What's the scale of the, what we think the scale of the problem is. Do we, is it like a 50 percent of blades have this issue? 20 percent of blades have this issue? Cause it sounds like it's more than 10 percent at the moment.
Edo Kuipers: It can be what we have seen, what we've noticed that in the past, blade designs had quite a lot of margin, safety margin in them. And what we've seen is that, yeah, in time we are as wind energy, we are reducing our margins. And because we are losing. these margins are getting closer to 1. 0. Let's say like then where we had in the past like 6.
These margins are getting lower and then the chance of loose bushings is also getting earlier with the, let's say, the 2. x or the 3 megawatt turbines. If you Build it in exactly the same way, of course, and I'm not sure, we don't know if the manufacturer has built it always throughout all these years in a consistent way.
We don't know that, of course. The only what we can do is observe what we see now. And what we see now is basically, first of all, the reserves or the mass moment, basically. The mass is getting higher with the given pit circle diameters and longer blades. remain on the same pitch circle diameter with the same number of balls for longer distances of rotor blades.
So lower reserve margin, that's one of them already. What we then also noticed, because we did three root cause analysis projects on different locations in the market. And what we noticed is that in all these cases, it was concerning polyester blades. It was concerning a special mat, which was basically wrapped around the bushing as an interface material.
And this mat had what we have seen an irregular distribution of the polyester resin in it. And it had these dog bone shaped, yeah, it was prefabricated parts in there. And what happens there is basically, due to this, unregular distribution of the polyester resin, we get differences in curing cracks, basically, our curing features.
Polyester resin is more sensitive to curing cracks, shrinkage cracks, basically, shrinkage cracks at the curing than an epoxy is. And if you then have this irregular distribution of your resin around these bushings, then you can also imagine that on different location, you get these micro cracks already from the start.
And then it depends a little bit on the reserve factors, which you had from the start, how long this will last. So what happens is due to these micro cracks, we are losing a certain amount of the bonding area of the area that has to transfer the loads from the tip to the pitch bearing, for example.
If we are losing this load carrying area, that means that the stress levels, they are going up, they are rising. And when we realize that there is a non linear relation between stress level on the, let's say on the vertical axis of your diagram and your lifetime on the horizontal axis of your diagram, this is not linear, but it's, let's say a logarithmic.
And. Realizing that if you are losing, let's say 10 percent of your area of your load carrying area and, or with other words, if your stress levels are raising with 10%, you can already lose like 50%. You can halfen your lifetime already.
Allen Hall: If I have a polyester blade, how would I know I have this defect in the blade?
Is there any way to detect it before the insert becomes loose?
Edo Kuipers: When you're a park owner, you have always these six months inspection intervals or one year inspection intervals. Then you go inside the hub and there's, let's say like a sealing done between your blade root and your pitch bearing.
This is this little line with sealing component filler. Check for cracks in that area, especially on the trailing edge, for example, and on the leading edge. If you see there are some kind of cracks inside, then cut it away with a knife and go with a filler cage inside.
Check how the distance is and do it on different pitch settings. So turn the blade, different pitch orientation, and see again this distance. Then you can measure if there is a variable cap going on, yes or no. And if you see a variable cap, for sure you have some way a loose bushing there.
Especially check for the trailing edge and the leading edge.
Allen Hall: Is there an audio component to this? Can you hear it when the turbine is running? Can you hear the blade shift around a little bit? Cause it's such a massive load. Is it making noise?
Edo Kuipers: No, I would, I don't expect that. I don't expect.
Maybe a little bit on your torque drives. You could see it in the pitching because you have a little bit more sweeping forward and backwards of your blades, if you are, but then you're already really far and then you really have huge, loosened boostings, but you can imagine that the pitch inertia changes in that respect.
So you will feel it on your pitch drives, but I guess Okay. Apart from that, the blade has then not flew off yet, but you're already too far.
Joel Saxum: It's already too far off. That's the question I want to ask. I want to get into here a little bit is okay. I'm now I'm asking from an operator standpoint.
So if I'm an operator, if we're doing a yearly inspection or end of warranty or whatever that may be, and we discover some of these gaps or we have, we go, Oh, here we're suspecting that there's something going on here. Okay. What is that, basically the delta in time between, I know you can't say it's 16 hours or, 22 days, but what does it look like?
Do you have, if it starts to loosen up, does an operator have a year or do they have a day? Like, how long before his up blade decides to come off?
Edo Kuipers: You have to ask a blade, but it depends in the mood when it's maybe when it's autumn earlier than it's spring. Not sure about that,