PEAK Wind Masters Site and Turbine Selection

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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YouTube channel here. Have a question we can answer on the
show? Email us! 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,