Weather Guard Lightning Tech

Leading Edge Erosion : Solutions and Takeaways from the International Symposium

Allen Hall, Nicholas Gaudern, and Rodolfo Meleiro discuss leading edge erosion at the International Symposium on Leading Edge Erosion in Denmark, focusing on the current state of the problem, solutions, testing methods, and key takeaways from the conference.

PowerCurve: https://powercurve.dk/

Arthwind: https://www.linkedin.com/company/arth-wind-services&consulting/

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Allen Hall: Welcome to the special edition of the Uptime Wind Energy podcast. And we are in Roskilde, Denmark at the 5th International Symposium on Leading Edge Erosion and Wind Turbine Blades. And I’m here with Nicholas Gaudern of PowerCurve and Rodolfo Meleiro of Arthwind. So we have a world perspective here on leading edge erosion.

We have Europe. Brazil, which is a lot of wind energy there. Thank you for being here and I’ll try to cover the America as best I can. So this has been a really interesting conference. It’s held at DTU which is, this is a wind energy center. So this conference has been organized and it has international flavor to it.

We saw presentations from India, Denmark, obviously there were German. Yeah. Presentations, Japan, China u. S. Sandia has been here. So there’s a paper from Cornell today. So there’s been all sorts of people worried about leading edge erosion. And I think it’s a really hot topic. And that’s the reason why I came to, to see the action here, because there’s.

So much that we don’t know. And I figured if anybody does know it’s a DTU, so it’s time to get over there and to find out what’s going on. So this whole podcast is really to discuss what we have seen and heard and try to figure out what the state of the industry is and where it needs to go.

And just first impressions, really One of my first impressions, I’ll just start. One of my first impressions was we have a long way to go. Yes, that we don’t know a lot. Yeah, and I wish I had been shocked so far So we’re at the end of day two and day one was pretty intensive on this or the mathematical Computational side.

Nicholas Gaudern: We don’t know a lot. We’ve had a lot more materials as well today So I think it’s nice that we have that really cross disciplinary approach here. So we’ve got materials. We’ve got structures. We’ve got data We’ve got metrology, meteorology, aerodynamics So it is bringing all of these expert field together which I think is really important.

There’s also the risk that there’s a lot of noise, because obviously there’s issues to be resolved in all of these different fields. And then, it may make it a little bit harder to focus on what really matters I think.

Allen Hall: There’s a lot of data smoothing that’s happening at the minute, from what I can tell, and different approaches to data smoothing, and I’m not even sure.

Everybody has settled on that.

Nicholas Gaudern: No, and I think we had like a discussion at the end of the day yesterday, like a shouting across the lecture theatre kind of discussion at the end of the sessions. And I think what was clear is there is more of a consensus about the AEP losses that we’re seeing, which is important.

And that’s really helpful because I think if you start seeing big scary numbers 15, losses, sure, those might exist in a very extreme scenario on a very particular type of turbine, but I really want to make the point here that is not the norm at all. We wouldn’t have an industry if 20 percent AEP every time they got some erosion.

So I think that’s been a really nice thing for me to see, this show that there’s show, conference, there’s there’s been a lot more, yeah. Say, convergence on small but significant numbers one and a half percent, two percent AEP losses. That’s plenty to worry about, we don’t need to.

Allen Hall: No, I think that’s right is because Rudolfo and I were just talking about that before we recorded here.

We saw a presentation that said 25 percent this morning, and everybody in the audience is no. No, they can’t be, but it does matter where you are in the world though. Yes. And having seen more recent pictures from Central America, India, some places in Brazil, they have really tough rain environment.

What happens in the United States is not what happens in Brazil.

Rodolfo Meleiro: Of the data I’m bringing, half of Brazilian fleets right now does not have LEP anymore. They have delimited. Yeah. Okay. So that’s the status Brazil has right now. Brazil is a relatively new industry. So the first older wind turbines are reaching 10, 12 years. Sure. And now some of those are requiring the maintenance.

And the owners are looking at, and that’s what you’re seeing, we’re seeing very degraded leading edge.

Allen Hall: Put your hand through the leading edge kind of degradation?

Rodolfo Meleiro: There is that, but that’s not common. That’s not common. But no more leading edge protection, no more top coat, laminate exposed, laminate damage.

That that’s a lot. So it’s a structural repair.

Allen Hall: It’s a structural repair, okay. All right.

Rodolfo Meleiro: And we were discussing that before. That’s extra cost. Besides reapplying the lesion edge, having to do the laminate repair, that’s a very extra cost, extra time for the machine stoppage, extra problems for everybody.

Allen Hall: I think that’s why we’re all so concerned about it. And this is the discussion that was held last night as part of the IEA group, right? What was the name of the IEA group?

Nicholas Gaudern: So there’s the IEA task 46, which is focusing on the leading edge erosion. And then there’s also, it’s not IEA, but there’s a Danish funder project EUDP funder called LEARCAT, leading edge roughness categorization.

So that is involving a lot of LM led by DTU and Powercurves also.

Allen Hall: And I guess. LM is representing GE. We don’t need them now.

Nicholas Gaudern: In a sense, yes. Exactly. So LearCat is also feeding in and collaborating with the IEA task because there’s a lot of shared knowledge and goals there.

Allen Hall: But they’re going different directions though.

That was my opinion being an electrical engineer and a lightning person is that the IEA was about trying to create some categories so that in a damage report they could say it was Leading edge erosion too,

Nicholas Gaudern: but yeah, I think the IEA is being more broad, they’re trying to bring in structural repair considerations and a bit more of a, it seems a little more holistic, whereas LearCat is very much focused on The aerodynamics and the air acoustics and the impact of different types of damages.

So there’s no structural focus there, for example.

Allen Hall: And I think this is where I think that program has a lot more to deliver in terms of what value it would bring to the industry. Yes. So the Leocat. Program from some of the discussions in the discussions were great yesterday because and maybe we could throw up some b roll here to show what we’re what happened, but in that program They’re actually taking real damage off of blades like taking a mold off of a damaged blade Yeah, then creating a leading edge of the putting on to a blade in a wind tunnel and actually doing real experiments in the wind tunnel to measure AEP loss, drag, essentially, drag to lift, and then acoustic noise to come off, different kinds of damage.

Nicholas Gaudern: And that’s really important because, we were talking just at the start of this session about what is the AEP loss number? Because you have to have a realistic number that people can believe in and trust. Because otherwise, it either gets way too much attention and people get scared.

Or it doesn’t get any attention at all. So you have to find that balance. Now, I think LearCat should deliver a lot towards that. So there’s this fantastic wind tunnel here, the Pool of Core wind tunnel, a really big, impressive new facility. And I was up there yesterday having a look at the first models for the LearCat project.

Oh wow, okay. So 3D printed leading edge modules. from these laser scans and these molds that have been taken in the field, and then they can carry out these really precise measurements to say what is the lift and drag impact.

Allen Hall: Because the ultimate result of this is to help. Wind turbines in the United States and in Brazil, which have tend to have a lot of leading edge damage, probably more than what I’ve typically seen in Europe, at least in northern Europe.

Yeah. Yeah. Yeah. So the issue then is computationally, you want to be able to take drone scans. This is what Aravista does. This is the power of Aravista approach to it, was basically taking some scans, some photographs, and then driving that to an AEP loss number so that you, the operator, can understand.

When do I schedule maintenance or do I schedule maintenance? You

Nicholas Gaudern: need to know when to make a decision.

Rodolfo Meleiro: Doing business is a business that has to stand for itself. Yes. All decisions comes down to downtime, to the cost, and yes, a reliable model and a reliable prediction of how much you are losing production.

Yes. And how much it will cost you to repair, that’s just a business case model. So that drives a decision, okay, this month is the correct month to stop the machine, do the repair, and go back to the regular production and have another maintenance predicted for X years, X months.

Nicholas Gaudern: And I guess the bigger the turbine is, the more important that is as well.

Rodolfo Meleiro: Totally the more important it is for many reasons, because. The bigger the turbine PP is increasing, so the erosion’s increasing, the bigger, the turbine, bigger problems.

Nicholas Gaudern: And the more money you lose

Rodolfo Meleiro: and the more money you lose because you’re not stopping anymore a one and a half machine mega watts machine, you’re stopping 5, 5, 6 megawatts machine.

So it’s much more power illusion by each minute, by started.

Allen Hall: Offshore. Multiplies that and then that was mostly the discussion here because Europe is so much offshore and America is just getting started and Brazil is going to be doing the same thing that America is doing here shortly, right? So instead of 5, 6 megawatt machines, we’re talking 10, 12, 18 megawatt machines.

Then it really becomes important because the cost to get out to the site to do a leading edge repair is so expensive that you’d want to do preventative approaches before you even deploy the blades, in my opinion. That’s not a discussion I heard this week, which is odd. Not so much. Why? What am I missing here?

It would seem to me as an OEM that I know that’s going to be a problem. I know when I put an 18 megawatt machine out in the water that I’m going to have leading edge erosion. I probably ought to put some protection on it just to. extend the lifetime?

Nicholas Gaudern: I think, Again I can’t speak for every turbine, but from what I’ve seen, every recent offshore deployment will have some form of LEP.

Okay. But of course, I think the technology has moved on a lot in recent years. Yes. From some of the early coatings and tapes to some more advanced now shells, soft shells, hard shells, other kinds of coatings. And that is making a difference, but I’ve still seen some photos of some pretty shredded blades.

Allen Hall: Yes, I have too. So again, that comes down to, I think it’s in the part of the discussion here, and I want to dive into this a little bit, is it’s not just the shell, it’s not just the coating. The failure mechanism for leading edge erosion has to do with the assembly of all of it. Yes. Because, and this is my simplistic approach to it, electrical person talking electrical things.

It’s much like a radio wave passing through different materials. There’s impedance mismatches. There’s boundaries, right? So you’re, when you, when the rain particle hits this surface, it then puts a force or transmits energy through this material. And at every boundary, if there’s a discontinuity, there’s a lot of force to rip it apart, to break it apart.

Nicholas Gaudern: We saw some interesting presentation yesterday when we looking at the hail impacts on on leading edges as well. And that kind of impact damage you get. So offshore, it’s just a much more hostile environment. Sure. In terms of the, so you’ve got that corrosion, the uv, uv, I think uv, the winds.

So yeah it’s tough, but it also makes it even more important to understand…

Allen Hall: what the losses are. Yeah. I think the key, right? If you’re dealing with an 18 megawatt machine, a 20 megawatt machine, the losses get to be. Astoundingly big. And because of the cost,

Nicholas Gaudern: Even if you’re using a few tenths of a percent AEP, that’s worth doing something about.

Allen Hall: Yeah. I totally agree. So I think there’s like a multidisciplinary approach to this. One is to understand what the materials are doing. And I haven’t heard a lot of discussion about that. Maybe just because the researchers are super smart and they already know when they walk in here. I haven’t heard the story.

I don’t, I’m not catching it, but it seems like the material has a lot to do with it. The application has a lot to do with it. The laminate in which is being applied on, the thicknesses of which is being applied, the temperatures, the humidities, all those things play into whether that coating or that shell or whatever it is, has a long lifetime.

And are we controlling those variables and is the word that the researchers are writing down and is in sort of technical terms, is that being translated to. To the engineers and the mechanical people on the floor who are actually doing the work.

Rodolfo Meleiro: I don’t always like to give the exact, not example, but effect every blade, two thirds of the blade weight is manually put by somebody in that, that’s the couch.

It’s true that roughly one third of the blade weight in resin that goes by infusion process. It’s more automated, but all the to shooters. The paint, the fabrics, the core, everything someone puts on his back go, sits in the molding position fits correctly. So we’re talking about your touch to blade.

20 tons are manually put into that blade, the product. Yeah. And then we discuss how much of the variable on the micros of thickness of coach right, will affect the life. So it’s so very complicated things. That right now we do with control, but it’s not that level of control. Yeah. So we have, there are a lot of variables.

Allen Hall: There’s a lot of variables in the application of coatings

Nicholas Gaudern: and the environments that these turbines sit in. I think that’s also an important thing here with things like rainfall, average annual rainfall, that will have a erosion, but also that doesn’t tell you the whole story, like even among the turbines on one site, the variability and erosion.

It can be quite dramatic, and it’s because of this handcrafted product, this, that we’ve just been saying, Rodolfo. and the really local microclimates and the individual operation of that turbine. So it’s really important that you get out there and you look at the turbines.

Allen Hall: And the data you provided yesterday was amazing because you looked at what, 1500 turbines?

Nicholas Gaudern: Yes. Yeah. Yeah. We were really fortunate to be able to present that. So we, we did a project last year with One of the big U. S. operators, one of the top four U. S. operators, and we looked at a sample of their fleet with, yeah, over 1, 500 wind turbines. There was eight different turbine models, so we have nice spread of models from different OEMs.

Okay. Rotor diameters between about 80 and 120 meters. And ages from two to 15 years. So we have a really nice spread population. And what we found was that firstly there’s a lot of damage so we receive all of the metadata from the drone inspections to say what damage is and where was it found, on those turbines, there was more than 95, 000 tagged damages.

Allen Hall: Whoa, okay. So pretty much everybody, every turbine had some level of Yeah, exactly. Danny Ellison told me that a long time ago. He said every turbine has leading edge erosion. Every one of them. Yeah.

Nicholas Gaudern: So that’s that’s really important because then you can start to look where is that damage?

And kind of unsurprisingly, most of it is towards the tip. Sure. So most of it’s in the outer 20 percent of the span because that’s where your tip speed’s highest and you’re going to get that erosion starting.

Allen Hall: But there was no, there was not when I got to the summary, I want to get to this point, it wasn’t like a particular OEM had a particular problem.

No. Everybody had basically had the same problem. And even turbines that were next to one another at the same wind farm had a different result.

Nicholas Gaudern: That was super interesting. So what we’re finding is by actually looking at The real inspection data and then coupling it to a model of that turbine. We aren’t going to detail, but basically we built a very nice area model from a laser scan, a lot of CFD modeling.

So we know exactly how the aerodynamics performs. You could have two turbines next to each other, one loses 2%, the other loses half a percent. And you need to understand that because you need to be able to prioritize what turbine you go to fix first and what to do with it. Otherwise you’re just wasting money.

Exactly. On average over that fleet, that 1500 sample, The average AEP loss we found was around half percent. Not dramatic, but enough. But the spread was some turbines losing nothing, some losing over two and a half percent. Okay. The spread is large and some of it’s quite dramatic.

Allen Hall: So there is an inconsistency, I think if I were making a product, I would like to see them all the road, roughly the same.

And that’s not what’s happening today. And is that coupled to some of the more materials based discussions we’ve heard about today, which is our focus around the mechanism in which leading edge erosion happens. That we’re just not paying that much attention to it. What is driving that? Or is it because when I get out in the field and, different lifts and different handling techniques and this blade set out in the field before we put it up?

Nicholas Gaudern: I’m interested particularly to hear your thoughts on this Rodolfo, because I know you’ve spent a lot of time in factories over the years. Cost. I want to say cost, there’s such a huge drive for cost out in the industry, that’s going to affect your solutions, your lead energy protection solutions, finish quality.

Rodolfo Meleiro: For sure. For sure. I have heard that men know more than once regarding what, which solution the OEMs decide to put on the blades and cost is a driver for that too. Sure. Then. But I think the biggest cause for all this variation is the nature of the business itself. As I said, we have too many manual labor operation.

They, I don’t know if you guys know, but right now I would say or dare to say that most, if not all of the blade leading edge is applied by roller.

Allen Hall: Yeah. Yeah. That’s my impression.

Rodolfo Meleiro: Yeah. And I have also, I think it’s almost a, it’s a an artist’s work to apply 15, 20 meters of leading edge and assure it to have the 0.

1, 0. 2 millimeters thickness. Without variation. Yeah. So there are variation, there are measurements for sure. But you don’t measure you don’t do the right measurements every 200 millimeters. So you have variation in this region and that variation is blade by blade. Yeah. And I think each blade is a, is a.

Badge, artisan artisanal work. Yes.

Nicholas Gaudern: Yeah, that’s right. But partially it is. Yeah. Yeah, it is. And I think, you do, cost is obviously really important because, the reason that we’re able to have such an international symposium today Is because the industry has been really successful in recent years at driving down cost, increasing deployment.

Wind energy is so big now. And even for someone who’s been in the industry for a few years, that was hard to imagine 10, 15 years ago. So cost is important, but I think now we’re getting these huge turbines producing so much energy, you can’t afford any kind of downtime. I’ve heard stories of blades on offshore wind farms being brought back to shore for leading edge repairs because the erosion is so bad.

Imagine the cost of doing that. That’s insane. And I think you’re not going to want to go for your super robust, super high cost LEP solution on all turbines. But for ones that are going to be in these extreme offshore environments you probably do.

Allen Hall: I haven’t even heard discussions about what the OEMs are offering, if anything.

And I know there’s some big operators here. I thought they would be asking very direct questions. We use X. What if we change to Y?

Nicholas Gaudern: Question. There’s a lot of, there’s a lot of products out there at the moment. And there seems to be a new LEP product quite often, I would say at the moment. And there’s.

Again, that’s why real trustworthy numbers come into it in terms of losses, because They’re all over the place. LEP changes aerodynamics, right? But I do think that maybe sometimes operators and OEMs get a little bit too hung up on a few tenths of a percent. So they say, okay compared to my polished wind tunnel model, if I put this LEP on the aerodynamics is a bit worse.

And I can measure it. And sure, you can, and you should care about the small things, but if it stops the erosion happening, that’s the bigger thing to worry about.

Rodolfo Meleiro: And I think the business case up to now the driver for the cost reduction industry was wrong. The OEMs always think about the machine price.

It must be seen the lifelong operation of the machine price. They said that’s cost is important and it was less important on the older turbines because they were more robust. They, they have less problems for many reasons, even though they have a lot of problems, but we are reaching something that’s strange because everything improved, the quality improved of the production, the quality of materials, the knowledge improved, but you’re having more problems.

And I think that this case of the leading edge is a possible improvement to, for sure, investing in apply the better. A stronger leading edge in the factory is 10, 100 times less expensive than applying a field.

Allen Hall: Yeah. And that’s, that I think that message is getting heard more and more is it’s better to get it out of the factory, correct, than have to do it secondarily.

The United States where we have 77. A thousand wind turbines running currently, something like that. There’s a couple hundred thousand blades. Yeah. There’s a lot. Probably right. There’s a, at some point, you can do so only so much in the factory, the vast majority of the problem in Brazil, United States, even Europe is you’re going to have to deal with what’s out there right now because you need to extend the lifetime.

I know the weird thing for me sitting in there is they’re talking about 25 year lifespans on turbines here, and I’m thinking. 10 years and it’s over in the United States. They’re going to repower this thing and it doesn’t matter. And the model is totally different.

Nicholas Gaudern: That is very different. I think if you look at lots of European countries, particularly Germany, they do run the turbines a long time.

They do. And there’s a lot of folks on life extension and really squeezing everything out. But I agree, all the customers we work with in the US, it’s this perpetual conversation about when we’re going to repower, when we’re going to repower. And they do consider a much shorter time horizon, I think.

Allen Hall: And that’s shorter.

Time span in the U. S., my thought is, and it’s on the same wavelength as Rodolfo, is put a better LEP on, out of the factory, if you can, if you can’t, most likely they are not going to buy that, right? That the operators typically don’t do that. All right, so you got two years of warranty, you got two years of warranty, and then you own it.

And the leading edge protection may not be included in the warranty. Depends.

Rodolfo Meleiro: If it’s normal, where else?

Allen Hall: It’s not in there. All right. So the model then in my mind is if I have a 10 year lifespan and I’m thinking us right now at year three or four, I’m going to have leading edge erosion. Now it won’t be bad enough that I have to go and do a bunch of structural repairs.

But what I will do was I would get a robot out there. Or something and get that leading edge repaired and at the same time put VGs on.

Nicholas Gaudern: Check if the business case is there, right? Again, that comes down to the simulation.

Allen Hall: I think the business case has to be proven by simulation, right? That you have to go look at the model.

The model in my head is based upon what Nicholas, you have told me. So I’m running the calculation up here. Yes, I think if you use something like an AeroVista to do the calculation, I think what you’ll find is. You put it on a year three or four, you’re trying to get to year 10, right? So you’re trying to make this blade, not touch it for about six years, maybe seven.

The way to do that is to put on a better LEP product, put on VG. So at that last year, nine and 10, it makes you power.

Rodolfo Meleiro: Just BC1E, which is also a driver for the industry,

Allen Hall: inspection. Inspection. Yes. So

Rodolfo Meleiro: That’s what’s missing in this case, because I think there’s a point, I have voice when I come to this conference, I have two questions I try to see if we’re moving to answer.

First one is how much we lost with the erosions and how we can prove that and then put a stone on top of that, because we totally agree, we’re all on the same boat that we have lost. But yes, we, when we still see numbers from half to 25, we don’t have a big alignment. And the second question is how much time my LEP lasts?

Yes. So those are the two questions. And right now, the best thing we have. It’s the simulations which show visible results and to how long it lasts is inspection. So you inspect and with inspections, you see the evolution of the problem and then you predict, okay, so with this level of the, of damages, I’m losing This amount of production, and then you see whether the curve of the cost of repair intersects with the cost.

And you decide that’s the sweet spot.

Allen Hall: So here’s the maintenance. Here’s the trouble, Rodolfo, with that approach. And so that approach is used in lightning protection all the time. Like they want to go do some, a five year experiment on to see if this works or not. The problem is the industry’s growing so fast in Brazil.

The industry is growing faster than it is in the United States. Yep, it’s going to explode. The amount of money going into Brazil to build wind turbines is insane at the moment, which is great for Brazil. But if you start making yourself several thousand turbine, say that’s a thousand turbines a year, 2000 turbines a year, 5,000 turbines a year, and you miss.

You have a huge problem, and then you’re right, and inspections become the number one priority to go out there and inspect, inspect, inspect. You should be doing inspection automatically. Yes. But what’s happening is they’re doing inspection plus an inspection because they have so much degradation they can’t keep up with it.

They’re trying to put a curve. Engineers are in the front office back there, or in the back office, sitting there going, Okay, this is year three, I have this much erosion. Next year, I’m going to have twice as much.

Nicholas Gaudern: But yeah go and look at it. Exactly. Go and look at it.

Allen Hall: You have to go look at it. I think that’s going to be the key.

I do think if you’re not going to go buy some better LEP system, the robots are pretty good. Now, Rodolfo, I went to Lafayette, I watched this thing go on. The robot installation is pretty controlled. Way better than I think is what’s happening in the factory. Am I wrong about that?

Rodolfo Meleiro: No, I was in Botafogo. I have visited.

I don’t know if it’s true. I have seen the robots. I will have to see. I think it’s available that you have robots doing that. And I agree. It’s unquestionable that a process done by robots. Yeah. A xip door process done by machine has less variation and it’s going to be here a great results. I totally agree.

I just would join that with the best material. And we have customers in Brazil right now that they’re doing exactly this discussion. I am going to do a big protection campaign. What material do I put? . And they’re trying, they, they’re, okay. I’ll put you three solutions. So I can run for two years, compare, so I decide what to do with the rest of my fleet, because they don’t have that.

Allen Hall: They don’t want to do it twice, though. No. So that, and that system sets up to do it twice. And that’s where this conference, I think, comes into the symposium. And the people here should be able to direct an answer to, because a lot of terms in Brazil, in a particular area, northeast Brazil.

And so the weather’s a certain way. I, we should be able to plug that into a model Northeast Brazil, four megawatt this OEM, and go, this is the right solution based on all the knowledge that we have. Am I crazy? I think that’s the only way to do it.

Rodolfo Meleiro: That’s the desire, that’s what they were to do.

But we are missing this is this theoretical. Yes. So they’re doing practical.

Allen Hall: Yeah, they’re doing all that. They’re doing all practical. And the operators are doing it, which is the worst way to do it because they’re already cut short because they don’t have a lot of time to sit there and monitor

it.

Nicholas Gaudern: So it’s hard. They won the the late presentations yesterday by David Manchi. Oh, yes. Really talking about a lot of the IEA work and the Sandia work and the work that’s been going on. I think he made a really good point about we have to do more modeling. And we have to trust the modeling.

Because when you start going to the field to hunt down a few tenths of a percent, it is nigh on impossible to do that with SCADA data. It is. So SCADA is a really valuable tool and can be used lots of ways. But you have to understand its limitations. And trying to track, say, leading edge erosion losses of a small magnitude.

is incredibly challenging. And I think there’s maybe been a little too much stock placed in it. Rather than saying we know how to model a wind turbine. We’ve clearly known that for a very long time because we have wind turbines. Yeah, we do. So let’s just extend that trust and that confidence to use those models in slightly different ways.

Yes. If we can design a blade. And it’s aerodynamic characteristics with a model, you can also understand how it degrades with a model as

Allen Hall: well.

But you, Nicholas, you’re taking it from the blade designer, which has used a BEM model into a computational model. And I think for a lot of operators that haven’t worked with PowerPer before, they don’t realize the power that sits in that model.

Yeah. If you have an actual blade scan, which you do, you’re not guessing at what the shape is. You’re actually taking the real model and applying. Real damage to get a real number out of it. Something they couldn’t measure with the SCADA system.

Nicholas Gaudern: No, exactly. And I think that’s, there’s been a lot of focus on the LearCat project.

The team at DTU, like the LearCat team at DTU Alexander, for example, he made a presentation yesterday looking at the CFD results, these really amazing CFD results of modeling the full 3D erosion in CFD and looking at how the lift and the drag changes, the flow patterns or the buildup of the turbulence.

And these tools are super powerful, but you’ve then got to look, how do you plug that into some of the industry standards, because the industry standard is still BEM, Bladel Momentum, that’s how you certify turbines, but

Allen Hall: you can’t use that to do these flying measurements and look at leading edge erosion.

That model will not produce accurate results.

Nicholas Gaudern: You’ve got to supplement it with the higher order models. Yeah. Like lots of things, each tool has its place. To me, the job of. of the engineer is to bring all the tools at your disposal together, understand the limitations and the benefits and then fuse them to get the best answer.

Allen Hall: Where can people go to see about LearCat?

Nicholas Gaudern: Where would you go on the web? So there’s a LinkedIn page for LearCat. There’s also a project site on the DTU you just search for LearCat on LinkedIn, that’s probably a good

Allen Hall: Okay, it’s important for operators and engineers involved in blaze to get to that site to see what’s going on to understand what the state of the industry is, because there are some powerful tools.

We can argue about what L. E. P. Solution we want to put on. However, we shouldn’t be arguing about what the losses are and what turbines to go fix. I think that Should be done and my opinion should be thrown on VGs while you’re at it because I think it makes the lifetime longer.

Nicholas Gaudern: But it’s a really good point and actually to throw a little bit of a curve, but we’re talking a lot about leading edge erosion.

That’s the seminar here, but. What about contamination? Exactly. Contamination, the kind of anti erosion, you’re building up the surface. But aerodynamically, it’s the same thing in lots of ways. It’s losing your lift, it’s increasing drag. It’s the same problem.

Allen Hall: And we used to get pictures from, Brazil can be pretty dirty at times.

Yep. Oklahoma, Texas. can be, the blades can be pretty dirty depending on the time of year, until it rains, basically.

Nicholas Gaudern: India, the same issue. The nice thing is that, a lot of the techniques and things that we’re talking about at Frozen, they can be transferred to think about contamination. The only real issue is that I see is you can’t put leading edge protection on to solve contamination.

Because it’s building up on the surface. Okay, maybe we could talk about really hydrophobic coatings and all these kind of things. But in general, you can say leading edge protection doesn’t stop contamination.

Allen Hall: Don’t get me started on hydrophobic coatings because I think we’re having all kinds of discussion about that.

But you’re right? Yeah. Uh, this is, it’s wintertime. It’s February right now, right? We’re in Denmark. It’s snowing today, of course. Every place I go, it snows. When I went to Latvia, it snowed. But those coatings, when you started adding any coating to a blade, isophobic coating, hydrophobic coatings leading edge erosion is a different animal and I think you changed the properties, based on what I saw here today, you’re going to change the properties of leading edge erosion.

Nicholas Gaudern: Yes. Yeah, exactly. They are linked and contamination is a difficult one to deal with. It’s also super localized. We see some blades, particularly up in like Norway, Sweden, five, six years old, they look perfect. Isn’t that insane? It’s true. But other blades, they’ve got proper crusts on the leading edge, but that’s, you’re mentioning VGs, that is where VGs can really come in.

And you see quite a few turbines out there with VGs towards the tip. And their main purpose is to give robustness to the power curve. Because when you have contamination or erosion, it damages the aerodynamic performance. It’s harming that boundary layer over the surface. And the VG is there to re energize the flow.

and recover the lift that’s being lost. So a VG doesn’t care if it’s erosion or contamination, it will still recover losses. So again, you do need to think as an operator about. LEP, repairs, inspection, but also upgrades, aerodynamic upgrades, because there’s a

Rodolfo Meleiro: lot of things you can do. But that comes out, interesting question.

Again, why the OEMs doesn’t put that on the factory? Already.

Allen Hall: I think that’s a really That’s a great question.

Rodolfo Meleiro: I One thing, we’re talking about today the maintenance of the leading edge. If all the OM when it sell the turbine, they says, oh, you have to consider every four years repaint the leakage. The operators just do what the manual says. Yes. Yes. I don’t think they say, oh, I want to do that. No they’ll do what the manual says. So if they Exactly. Sell the turbine, even maintenance plan. Yep. , they they, the owner they will put on this business with, if he decide to buy the turbine, he just follow the business plan and that’s it.

Nicholas Gaudern: Your point about VGs in the factory is an interesting one. I would say, again, anecdotally

Rodolfo Meleiro: It isn’t a tip because of the first work that I did, the Yes, the More and more I’m doing that right now, but That’s the chip. I have some knowledge.

Nicholas Gaudern: No, you don’t see that so much. I would say Siemens, Siemens put on quite a lot now.

Allen Hall: Has done it more recently. Yeah. That’s the only one I really have seen.

Nicholas Gaudern: Tends to be as an aftermarket from what I’ve seen. Yeah. And that’s just because I think firstly, the knowledge level has been increasing quite dramatically in recent years because of things like the symposium we’re at now. So the knowledge of how a VG can help you.

I didn’t know that it’s a cynical thing to say, but I think OEMs really like their service business. They make a lot of money from service.

Allen Hall: I just saw Vestas numbers and you have a separate line item for service. It’s amazing.

Nicholas Gaudern: I think given the choice, they’d maybe prefer to put some parts on as a package they sell separately a few years down the line.

Sure, it’s a, it’s the whole money. But aerodynamically, yeah, as you say, Rodolfo, most new big blades have VGs in the route. Anyway, towards the tip, it’s a bit different between the OEMs for sure. But, um, they can really help.

Rodolfo Meleiro: Allen as you said, they can help to give robustness. Yes, it’s the robustness.

Protect it from the degradation, minimizing the effects of possible loss.

Allen Hall: Yes, exactly. Now, the best new product that Rodolfo and I were talking while you were out for a minute, Nicholas, was the best new product we’ve seen here so far is this company called Helicoid. I’m going to pronounce, I can’t pronounce it because I’m American, but it’s spelled H E L I C O I D.

Helicoid? Helicoid, yeah. All right. Helicoid. So the presentation started off this we’re from Hale Co. We’re based in the United States and the uk and we’re making pickleball boards, perhaps . I don’t know where this discussion’s gonna go, but it’s gonna be interesting. Let’s go. So the it the technology, I’ll describe it as a technology.

The tech technology is. They’re using the fiber construction of a, was it a shrimp? Like the little critter that he beats, right? Yeah. So on some of them they have this hammer device that they use to repel crabs, because crabs like shrimp evidently. So these shrimp have these hammer devices which have this fiber that’s really hard.

Now, I guess they can use it to crack the shells of these crabs and defend themselves. But when they start looking at this fiber construction, it’s really tight. So there’s not a lot of other stuff. It’s almost all fiber. And what they realized was if they took unidirectional fiber and instead of going 090, 090, 45, you go 030, 60, 90, something like that, where you have less.

space, as resin rich areas, that it makes it extremely tough. And when you rain erosion that material without any coding on it at all, you don’t get the punch through. So it’s the uni plies and the 090 plies that we put around the leading edges today, if we haven’t, or just glue join, that we punch through.

So when we saw, when Rudolph and I saw that, I was Like, ugh. Yeah, here we go. Yep. So even if the LEP fails, you’re probably not gonna, it is gonna give you a longer time before it eats to the laminate. We have to do a structural repair, so it lends itself to robotics. That, okay. I have some, I see the coating is missing.

I’m gonna call aeros. They’re gonna be here, in three months. Three months. It’s not gonna eat through that laminate because it’s designed in a different way. To last longer terrain erosion. Rodolfo, is that the logic there?

Rodolfo Meleiro: That’s the logic and I think that’s genius because we go back to the same discussion to have time to plan the maintenance on the right time.

Yes. And that’s a big difference. We’re discussing that also. Doing the repair for only the paint cost X. Doing the repair for the paints plus the laminates cost between two to three X. Yes. So it’s a, just talk about doubling, maybe three times the cost and time of the machine to stop it.

And you have a material or you have a construction that can protect you from that. So you have time to do the repair before you reach this two, three times penalty. That’s great.

Allen Hall: The pictures that they were showing was of a standard leading edge design, fiber design, right? And then they applied this material over it as a Couple, couple.

Rodolfo Meleiro: Like two layers of this stuff, right? It was they did a reference sample, like six layers, normal material. Oh, yes. And the other one, four layers normal, plus two layers of dead material.

Allen Hall: Exactly. And So it would replace some of the structural applies or could be secondarily added because how much of this material would you really need on a blade?

Half a meter wide, maybe? It wouldn’t, yeah, it wouldn’t be necessarily, you’re not using millions of dollars of this material.

Rodolfo Meleiro: You, I would consider that as a, And when you do the lesion as a protection just semi width of the paint. So we’re talking 200 millimetres, 300 millimetres maximum. Yeah,

Nicholas Gaudern: You don’t need to cover more than that.

Rodolfo Meleiro: Yeah, it’s a little much,

Allen Hall: it’s a little much. So it’s a small amount. It’s something that would already fit into the manufacturing process, whether you could injection, inject resonant to it, whether it flow right. And all those things have to be worked right. And that’s when you have tight fibers like that, it can be a little bit difficult to get the resonant between them.

But. The logic makes sense, that it’s, it could be a simple addition for an OEM or even in a repair situation, like if I had a cracked open leading edge, I could repair this material, so I’m trying to get to my 10 year lifespan in America, I would do it with this material. In fact, I probably wouldn’t go fix the LEP at year 9, I would just let it go, because I know I got probably a year with this stuff.

Nicholas Gaudern: Can protect. Yeah. A part of you might be losing lots of AEP.

Allen Hall: You’re gonna lose a lot of AEP, but at that point, the way that Americans run their turbines, Nicholas, you don’t want to know. But I do think there is a plan to get more power out, right? And I think overall, it’s an overall number.

Sure.

Nicholas Gaudern: And. This is a perfect application for composites, right? Which you can put the fibers wherever you want them, whatever orientation you can do it.

Allen Hall: So the pickleball solution actually turned into something real. So that presentation, which didn’t start out on the best foot, my opinion, all of a sudden at the end, I’m like, holy moly.

I think this is good. Is it me? We’re both over here. Wow, this is cool. Because I do think that kind of technology can help get us bias a little more time LEP solution is going to be, which we don’t

Nicholas Gaudern: Well, we had a, there was another presentation yesterday on metallic research. Obviously not a new concept and they were showing, obviously the upfront cost is going to be a lot higher, but lifetime costs should be much lower.

Yeah, it is, it’s,

Rodolfo Meleiro: I think the concept is right, but the implementation proposals, I think it’s lacks something, it’s too, I think it’s complicated.

Allen Hall: It’s complicated.

Rodolfo Meleiro: It’s much more complicated than the proposal, but yeah, I think that there’s a point. Maybe the, as we discussed it, maybe we should have some more focus.

So on better materials. On a different approach to really extend the life, really extend the life or to have a cost effective material that gives us this maintenance plan that can be really predictable and affordable.

Nicholas Gaudern: Yeah. I’m not sure you need to go full metallic leading edge on most onshore sites.

It probably is overkill.

Allen Hall: When the discussion about metal leading edge has come up, I thought we are still in a new frontier. We have not. Got to a solution. We haven’t arrived at a solution. We’re still in the middle of a solution We’re using a solution that was on propellers back in the 1930s. That’s where we’re at right now I was like we’re trying everything.

Yeah that we should be keep ourselves open to everything and When if it’s a composite solution if it’s a leading edge protection coating or a shell or maybe it’s metal who knows Yeah, but we gotta hurry and it’s it’s a difficult one, right?

Nicholas Gaudern: Because you don’t want to you don’t want to stimmy innovation You don’t want to stimmy research.

Sure. However We can’t pretend that the wind turbine industry is a cottage industry anymore No, the number of turbines that are being installed means that we do have to speed up. We have to speed up. I don’t think we can have 10, 15, 20 competing LEP solutions that have vastly different properties and and maintenance regimes because there’s just too much choice.

And then every time an operator wants to decide on a solution, they don’t really know what to pick. They then have to set up their own test campaign because there’s not enough data out there. And then I just feel like we just keep going in circles a lot. So yeah, there’s that balance, which you have to innovate, you have to try new things, you have to open the box.

But we also have to have a solution that surely a lot of people agree works.

Allen Hall: So that gets to my point about time frame. And one of the pain points for me watching this is I know how painful it is for operators to deal with this and all the tools and resources they’re trying to go get. At the same time the academic part of this.

is out to 2025, 2026, which is fine. I think that’s fine, but we’re on 2024. We need solutions now.

Nicholas Gaudern: We gotta, how many gigawatts is going in

Allen Hall: next year?

Yeah, way more than we even want to think about, honestly, because the consequences of doing. Having leading edge erosion problems offshore gets super expensive in the United States.

The opposition to offshore wind is at fever pitch at the moment. If they had to drag back. Blades to get repaired next to the New York, Boston, Philadelphia corridor, that would erupt. And you can’t have that. I think as an industry, you can’t have it as maybe as an OEM, you could survive it. But as an operator, I don’t know if that would really help your case.

Nicholas Gaudern: I think that the kind of event right now at this symposium. It is bringing lots of the right people together. Operators, OEMs, academia, third parties, all have to be talking together. You need to share as much knowledge as possible so that people don’t have to go and repeat a test all the time because they want their own data.

Allen Hall: It’s true. It’s nice to have your own data, but that data on a backup, what is published, right? It’s that validation piece. Fine. Go run the test and we’re going to go visit the R& D test systems, Rainerose facility that are building at DTU, which is supposedly magnificent. It sounds magnificent and we’re going to go tour that tomorrow.

So I’m really interested to see how tight the controls are. This is getting back to the variability problem. Rainerose and testing, one of the complaints obviously is, Every rain erosion test facility, that’s not R& D test systems rigged. That gives you a different result. R& D test systems just narrowed that down quite a bit, for sure.

Again, the variability is too much, and yeah, that’s why an OEM goes out and repeats these tests, is because they know, I can get a different result.

Nicholas Gaudern: But yeah, it’s a big time suck that we can’t necessarily afford.

Allen Hall: No, but if I’m if I’m an OEM today. And I don’t have an internal rain erosion test set. I know where I’m going.

Yes. I’m coming to Roskilde. I’m going to the DTU rain erosion facility because they know what they’re doing and they have the best, going to have the best facility in the world. And the consistency of that test should be better than anything else you can get. And even just talking to some of the people that work there their knowledge of rain erosion and the types of variables that apply in that test was.

Astounding. I’ve been around main rosin testing a long time, almost 30 years. So I’ve seen a lot of it that is going to be crazy. Great. Yeah. It’s fantastic. Rodolfo Nicholas. This has been fantastic. It’s great to see you. Yeah. I’d like to see you in some place where it’s warmer. We got to get to Brazil.

We got to get to Brazil.

Rodolfo Meleiro: It always gets snowy. You’re going to the wrong place. You go to Brazil. There’s no snow anywhere.

Allen Hall: Yes. Yeah. We should go to Brazil sometime. But yeah I appreciate you having me on the podcast and this has been fantastic. So maybe we’ll see you here next year. Absolutely. For the sixth. Thanks for having me. All right. Pleasure.

Leading Edge Erosion : Solutions and Takeaways from the International Symposium