Show notes
Lene Hellstern, Director of Engineering at PEAK Wind, discusses the complexities of onshore wind siting, the advantages of using LIDAR technology, and strategic considerations for turbine selection.
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Allen Hall: We're back with Lene Hellstern, the Director of Engineering at PEAK Wind, and we're talking about onshore wind siting, which is a really critical issue that a lot of operators have difficulties with. And I've seen it in the United States and it's not good.
And I'm wondering from your perspective, what are some of the problems, Lene? Well first, welcome back to the podcast.
Lene Hellstern: Thank you. And thanks for having me repeat experience last time, so I hope so. I thought I'll pop in again.
Allen Hall: Well, it's good to have you back and thanks
Lene Hellstern: for coming to Copenhagen.
Allen Hall: Yeah, well we love Copenhagen.
It's great. Uh, I just wish it was a little bit warmer. Yeah, the sun is terrific. Yeah. When you're in it, well, at
Lene Hellstern: least I fixed that. Right. Yes. It's not raining. It's not raining. Yes.
Allen Hall: We, we quite enjoyed it. Uh, but I'm trying to get an understanding of what the underlying issues are with onshore wind siding and why some of the operators have difficulty later on.
Let's just start with the sighting [00:01:00] itself. Yeah. Is usually, we'll see a wind mast out on site for several months, maybe a year, maybe two years. To try to get some wind data. We would
Lene Hellstern: really like that. Yeah. Okay. But, uh, the preferable measurements are lidars.
Allen Hall: Oh, lidars. Yeah. I have not seen a lot of lidars in use.
Lene Hellstern: No. You, you need to get some more.
Allen Hall: Why?
Lene Hellstern: Um, because they reach higher.
Allen Hall: Okay.
Lene Hellstern: Um, and you can, uh, you can, you can move them around. Right. And the hassle of installing a Met Mass that's a hundred meters tall, is, uh, is it a problem? Quite, uh. Quite it, it cost a lot more. Yes. Um, and, and the lidars, they, they just, they're better and they measure higher.
And you can, you can have one sort of mother lidar and then you can move the other around and you can cover your wind resources and site suitability much better on the site. So I would definitely recommend
Allen Hall: lidars. Okay. How the lidars use a [00:02:00] good bit of power to make them run, correct? Yes. So you need a decent power source?
Yes.
Lene Hellstern: You do? Yes.
Allen Hall: Okay. Yeah. I, is that one of the difficulties why they don't use a lidar? Is it just in a lot of remote areas, they don't have the power source to run it?
Lene Hellstern: It could be, or it could be the, the lack of knowledge. Right. Traditionally we have used med masks, yes.
Allen Hall: Forever.
Lene Hellstern: Uh, so, so it could be, and then there are also some, um, uh, some issues with uncertainties because the lidar is the, the standards are not up to date.
I would say that's the political way correct way of saying it. So. Eh, the standard actually introduces more uncertainty on the lidar that's really not necessary to, due to a calibration with a me mast. Um, so that there's some, there's some things that needs to improve in that area
Allen Hall: because a lidar should be a lot more accurate than a met mast.
Lene Hellstern: Yes. Yeah. Yeah. But, but the, the downside of the lidar, so that, that is not often we see that, is if you don't have enough particles in the air, you have [00:03:00] an issue because then you are, you're simply not gonna be able to measure. The, the, uh, velocity of the particles because they're not there. And then you have a low availability on your measurements.
But, you know, most places there's, there's a quite a lot of dust. There's pollution. Um, so there, there are things in the air that we don't see, but the lighter sea and then you can make the measurements.
Allen Hall: And as the hub heights have gotten taller, it gets a lot more difficult to get a met mass up that high.
So the lidars go can measure winds. How high up in the air? How many meters? I
Lene Hellstern: think at least 250 meters. Wow. And, and you want, you want to, you know, traditionally you would only measure at hop height, but you wanna measure at the, the, the rotor surface, right? So you wanna measure at tip height, and you wanna measure at lower top tip and lower tip to, to see what, for instance, what's the wind share across your, uh, rotor disc.
Um, which
Allen Hall: you cannot really do with a met mast at all. You can't do that. You have no [00:04:00] wind share knowledge. From that instrument? Sort of, yeah,
Lene Hellstern: you can, because you can make, you always, you, you have a met mass that's at least at hop height, and then you have, uh, anemometers and wind veins and I don't know what on all the way down.
Um, and you can with, without that equipment, you can, you can measure on the lower part of the rotor, but not the upper part. So, so you, you do get some possibilities to measure wind share, but not as good as, um, for instance, a lidar. Yeah.
Allen Hall: So how many lidars would you typically need on a 100 turbine site?
Lene Hellstern: Well, that depends.
Allen Hall: Okay.
Lene Hellstern: Because you have a, if you have complex terrain,
Allen Hall: right?
Lene Hellstern: Yeah. You may want a lot. Right. That's what I
Allen Hall: was wondering if the more hills and valleys, the, the more lidars you will need, or more samples you'll need, or maybe the longer duration you'll need. Yes.
Lene Hellstern: Yeah. And you, you would wanna, you know, it's always the best to measure it.
I think it's [00:05:00] ideally five years. Nobody does that five years. Nobody. No, no. But you should at least have two, right?
Allen Hall: Yes.
Lene Hellstern: Uh, and then you should do a proper long term correlation. Um, so, so that's, and how does
Allen Hall: that, how does that accomplish Right now, let's just say we have a met mass. What I typically see is, has been a met mast out in the middle of the United States where the winds are pretty good.
Speaker 3: Yeah.
Allen Hall: And they have data. They have some data. Yeah. So typically I've seen them out there a year, maybe two years, and then. The, but the sites are massive. Yeah. They're, they're square miles. Yeah. Dozens of square miles. So it's big.
Speaker 3: Yeah. I
Allen Hall: dunno whether it's in kilometers, but a lot of square kilometers. So then they are trying to interpret interpretate that data that they have from the Met Mass on top of that.
I think they're looking a little bit forward in terms of who, what other wind farms may be surrounding us in the next several years. Yeah.
Lene Hellstern: And that's, that's one of the challenges we have because there's a lot that. Uh, you, there's a lot of guessing.
Allen Hall: Yes.
Lene Hellstern: Um, and so if [00:06:00] you are planning a wind farm, you wanna know what goes on in the area.
You wanna map out the already existing turbines, uh, and what, what hop height, what rotor size, because you wanna be able to model them in your calculations.
Allen Hall: That was really good. Get to my question about how difficult this process is and how you try to address it. In the United States, we turn over wind turbines every 10 years, so there's a repowering happening and.
Almost always, the rotor size gets substantially bigger. 20 to 30 to 50% bigger. Right. So there's fewer turbines, same location. Yeah. And the turbines are roughly in the same spots, but they're just bigger rotor diameters. How do you then prepare for that? Do you use the old data or is the old data even applicable?
If I'm really dramatically increasing the rotor size, do I need to be doing more? LIDAR measurements before I make that repower, or how do I even cite that? Right.
Lene Hellstern: Uh, you can, if you have some good SCADA data from your turbines, you can do some [00:07:00] modeling. And many of the sites actually have a met mast. They do a lot Yeah.
As a reference, right? Yes. Right. But that will be on it, it will have sectors where there's a lot of weight from the existing.
Allen Hall: Okay.
Lene Hellstern: So, and so I would, I would, I would try, I would filter your SCADA data from your site and see if, can I, can I use this? I'll take a look at the mid mass state and see, can I use this?
If not, I'll start a me mass campaign. Now the problem is if you're reusing the spots now, well first of all, that's a little bit difficult reusing because your foundation is dimension to an old generation turbine. Uh, let's say take someone a hundred, a hundred, uh, meter rotor, right? Right. But now you're going up in size.
Um, so that means everything gets heavier and bigger, right? So your foundation may not be suitable. The old foundation, normally they're over dimension. So you can, you can extend life or you could repower on them, but you would want a bigger turbine. [00:08:00] So you don't necessarily want to use the opposition, right?
And then you would wanna know what is in the pipe. You know, when can I get my, when can I start digging? Right? When can I start installing? Uh, what is in the pipeline at that point from the OEMs? Because sometimes it actually takes five years from, you start planning until you, you, you start digging. And in that time, if you, you,