Show notes
In this Uptime Spotlight, Joel Saxum discusses the C1 Wedge Connection with Managing Director of C1 Connections, Jasper Winkes. They explore how this innovative wind turbine foundation interface addresses challenges in the expanding offshore wind industry, especially for larger turbines. The design benefits include structural enhancements, faster installation, lower maintenance needs, and possible cost savings for both offshore and onshore wind projects.
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Joel Saxum: I'm Joel Saxum filling in Allen Hall's shoes as your host for this innovation focused guest episode of the Uptime Wind Energy podcast. Today we're talking about wind turbines and massively important connections in between the towers and transition pieces. Bolted L flange have been used for decades to connect steel cylindrical structures.
We know this. However, as the wind industry continues to push structural engineering limits with increased capacity for these behemoth wind turbines, specifically offshore, a need for new tech to solve the loading problems has emerged. Enter stage the C1 Wedge Connection. With over seven years of development and two years in the field Jasper Winkes and team have developed the next generation of steel structure connections. Jasper, welcome to the show.
Jasper Winkes: Thank you very much for having me.
Joel Saxum: Great. So we, you and I talked a little bit off air about kind of the technology where it's been, where it's coming, where it's going, but it's driven by offshore industry trends, right? We've all seen, if you look in the North sea, small turbine big, Bigger, all of a sudden now we're 15 megawatts and some people around the world are talking about what could be the next generation.
What are those trends that are driving your technology?
Jasper Winkes: Yes, indeed. As you mentioned, we've seen a massive growth in turbine size over the years. And on one hand, that's of course the growth of the rotor. And they always say the rotor is the motor. So you need large rotors to extract energy from the wind.
But of course, large rotors also require tall towers. So we see that there's an exponential increase in overturning moments over the past years whereby essentially the bolted L flange has now reached the point where it is already struggling to deal with the loads and soon will no longer be able to take the loads.
And of course, where that point lies is really project specific but it's an issue that has been flagged by many industry experts for years already.
That L flange has been used since we started putting steel together hundreds of years ago, so in, but in a turbine, you see the L flange in between every tower section in even up in the tower, some places, right on, in a cell on blades, whatever.
But what we're focused on is tower connections and even the transition piece and some of that monopile interface. So where, and what are the issues that these, the traditional L flange technology, you explained it to me, maybe you can explain it here to our listeners.
Yeah indeed, we see that the heavy loaded connections, and of course, the more down the substructure, the heavier loaded the connection is, because you've got a longer lever arm to where the rotor is pushing on the structure itself.
You see there are overturning moments which are already approaching one giga newton meter. For people to put it in perspective, that's a 50 kilometer long stick, and then you lift a Tesla at the very end. So it's massive loads that need to be transferred through these interfaces. And the problems that companies are having is, first of all, there's a limited number of bolts that you can put on a certain circumference.
So for a bolt at L flange to scale up further, at a certain moment, you cannot fit any more bolts on the circumference. So then the next logical step would be to grow in bolt size. But for a long time, the M72, so a metric dimension stud size was the largest stud in the industry. But we now see a massive base where some companies are considering M80 and even M90.
And that basically brings you into a field where on one hand also your flanges are growing massively in size. But also the tools that you need to handle. We're talking about tools that can easily weigh 70, 80 or maybe even more kilos. So there's a real challenge in getting those connections made and then on top of that everything of course needs to be done under time pressure.
Because there's this expensive installation vessel that needs to wait for either the transition piece or the tower to be connected to the foundation. And we want to solve that issue.
Joel Saxum: Yeah, so the other, you go bigger in bolt size or you need more bolts so then all of a sudden your tower would just start increasing in diameter to a point where it doesn't, the cost efficiency isn't there anymore in the tower.
Jasper Winkes: Yeah, so at a certain moment you would have to increase your base diameter, but of course a larger base is exactly in the splash zone attracts more wave loading, which results in more fatigue damage in your foundation. So The optimum is basically not having to increase your interface diameter that much, but still being able to connect it properly.
And our connection technology allows that because you have a higher ultimate capacity, a much higher fatigue capacity, and we can enable both safer and faster installation.
Joel Saxum: Okay, so let's dive into the technology itself now. I've looked online and I've checked out some of your white papers and this stuff and it looks to me, you guys have done a great job of marketing the thing because.
From someone who is not a structural engineer, I can look at it and go, okay, that makes sense. But maybe you can explain in better words than that.
Jasper Winkes: Let's kick off with the reference. The reference is the the L flange, which is essentially two flange bodies, which are connected to a tower and foundation.
So let's focus on that interface for now. They're welded at the factories and offshore they need to be connected. So it's basically a flange that's protruding inwards into the tower and they are sticking studs in. But it also means that the stud or the bolt is not in the line of the, where the load is transferred.
So it's an eccentric connection by default. What we have is we also have a flange connection. However, the flanges are different. We have a fork shaped upper flange and a shaft shaped lower flange, which are welded to both the tower and the foundation. And they slide into each other. And then we have a fastener that is radially inserted from the inside of the tower in that fork shaft combination, and thereby pulls the shaft on top of the fork.
And it's essentially a preloaded connection, with the main difference being that it's not eccentric. So we have a centric connection, so it's directly in line with the load transfer path. But we are generating a very high preload with a stud which is basically perpendicular to the load introduction. And we are increasing the load by the means of wedges.
So we are pulling two wedges together that essentially force two bodies apart. And that way people can see it, of course, online how that generates a symmetric preloaded connection.
Joel Saxum: Okay. So I think the, one of the most important things here when I look at this is, okay, if I'm a traditional flange connection, it's literally on my desk here, I have two coffee cups.
It's like setting two coffee cups on top of each other. And then the crane has to hold the top piece and you got to figure out how to get the studs or the bolts in and make it all line up, or maybe put some pins in or something. So you have this. this moment or this time during construction or during connection that is I don't know how to explain it.
It's a highly critical moment. All hands on deck. Make sure this thing goes perfectly right because you're not only trying to put load down, but you're trying to align it to get into the holes correctly. But your technology and like the way you weld the flange on is the way the flanges are designed.
You remove that critical moment where once it sets, it's. It's in place.
Jasper Winkes: Yes, indeed. So Indeed, current installation of L flanges has this time critical also safety critical moment where you're trying to land two flanges and with some kind of pins, they try to line up the holes. We've taken that in into consideration when we designed our connection.
So essentially when the upper flange, which is then part of the tower is lowered onto the foundation, there are several guides and bumpers that align the tower directly in the right orientation. Such that the moment that the flanges connect, we have a quick connection system that directly connects the tower to the foundation.
And once that connection has been made, the crane can directly disconnect the tower from the yeah, the tower can be directly released and you can start lifting, for example, your nacelle. So you can save significant amount of time.
Joel Saxum: The safety part of this is a big thing. Talking.