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IRENA – MARTINIQUE CONFERENCE ON ISLAND ENERGY TRANSITIONS Workshop C : Wind resources and technologies for islands
WIND MEASUREMENTS ON
ISLANDS :
THE BENEFITS OF USING
LIDARS
Martinique, 22th June 2015
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Eoltech short presentation
Wind resource assessment, background and state of the
art
Wind measurements with LiDARs
Specificities of the wind resource on tropical islands
Main conclusions
Summary
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Eoltech at a glance
1st French independent expert in wind resource assessment
Pre and post construction wind potentiel assessments
13 years of expertise, more than 7 GW of projects analyzed
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Wind resource assessment, background and state of the art - 1/3
Main characteristics of the wind resource
High temporal variability
Order of magnitude ± 10 % on wind speed from one
year to another over 15 years
High spatial variability
Depending on the complexity of
the topography and the landscape
High sensitivity wind speed versus production
3 % variation on wind speed could lead to 6 % to
9 % of variation in production
Wind resource assessment subject to high level of
uncertainty without measurement on site
+11 %
- 9%
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Wind resource assessment, background and state of the art - 2/3
On site measurements, the starting point of a standard process
Spatial
extrapolation
State of the art : 1 year of measurement on a representative point of the site at a height the closest to the hub height (2/3 minimum)
Wind
measurement
1 year on site
& Data analysis
5 6 7
0
20
40
60
80
100120
Vitesse de vent (m/s)
Hau
teu
r (m
)
Long term
prediction
Régression secteur : -15/15
VRef (m/s)
VSite (m/s)
5 10 15 20
5
10
15
20
25
+11 %
- 9%
Long term energy output
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Wind resource assessment, background and state of the art - 3/3
On site measurements with met mast
Met mast equipped with sensors (Cup anemometers, Wind vanes…)
Height between 50 m and 80 m
The most recognized process for wind measurements
The fequency of the reflected signal is modified
(Doppler effect)
o Difference of frequency
o Signal return time
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
The LiDAR - Operating principle
A laser beam is pulsed by the LiDAR (Light Detection and Ranging),
and reflected by the suspended particles
Wind speed
Height of measurement
Different heights of measurement possible
Usually between 40 m and 200 m
Aerosol speed
LiDAR
Aerosol Speed = Wind speed
f1
f2
Height
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
The LiDAR - Who uses it ?
The LiDAR - Accuracy
Well-proven technology on a non complex area
Recognized by industry for wind resource assessment
On going IEC standard for power curve measurement
(started in 2014)
We are talking about the
technology,
not the product itself
Used by developers, manufacturers, consultants and research institutes
More than 400 Lidar Windcube by Leosphere have been deployed
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
The LiDAR - Advantages
Easy to install and remove
No building permit required
Satisfactory measurement quality up to 200 m
Low risk of wear due to climatic conditions
(especially corrosion)
But keep in mind….
Precautions of installation are required
(flat terrain, avoid obstacle in the volume of the cone)
The technology is proven, not each device
Conclusions : The LiDAR is an alternative technology to masts for wind
measurements, recognized and easy to implement
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Specificities of wind climate on tropical islands (1/3)
Usually, one year of measurement is strongly recommended to take into account the
seasonality effect of wind resource
Per season Main impact on
Different wind regime Prevailing wind direction
Different landscape (crops or forests summer versus winter)
Vertical wind shear
Atmospheric stability conditions Vertical wind shear
In tropical areas, especially
on islands, the wind climate
is a result of stable trade
winds and temperature
variation
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Specificities of wind climates on tropical islands (2/3)
Seasonality effect on wind resource
Per season Northern France Island on a tropical area
Wind roses
m
2010 - Q1 2010 - Q2
2010 – Q3 2010 – Q4
m
2010 - Q1 2010 - Q2
2010 – Q3 2010 – Q4
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Specificities of wind climates on tropical islands (2/3)
Seasonality effect on wind resource
Per season Northern France Island on a tropical area
Wind roses x Not stable Stable
Landscape(farmland / forests)
Atmospheric stability conditions(temperature)
Jan.
Feb.
Mar
ch Apr.
May
June Ju
lyAug
.
Sept.
Oct
.Nov
.Dec
.0
5
10
15
20
25
30
Av
era
ge
te
mp
era
ture
(°C
)
Jan.
Feb.
Mar
ch Apr.
May
June Ju
lyAug
.
Sept.
Oct
.Nov
.Dec
.0
5
10
15
20
25
30
Av
era
ge
te
mp
era
ture
(°C
)
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Specificities of wind climates on tropical islands (2/3)
Seasonality effect on wind resource
Per season Northern France Island on a tropical area
Wind roses x Not stable Stable
Landscape(farmland / forests)
Atmospheric stability conditions
Jul-1
1
Sep-1
1
Nov-1
1
Jan-
12
Mar-1
2
May-1
2
Jul-1
2
Sep-1
2
Nov-1
2
Jan-
130.20
0.25
0.30
0.35
0.40
Wind shear on 6-month rolling periods
Starting date of the 6-month roling period
Win
d s
he
ar
Aug-0
5
Oct-0
5
Dec-0
5
Feb-
06
Apr-0
6
Jun-
06
Aug-0
6
Oct-0
6
Dec-0
6
Feb-
07
Apr-0
7
Jun-
07
Aug-0
70.20
0.25
0.30
0.35
0.40
Wind shear on 6-month rolling periods
Starting date of the 6-month roling period
Win
d s
he
ar
Summer winterwinter
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Specificities of wind climates on tropical islands (2/3)
Seasonality effect on wind resource
Per season Northern France Island on a tropical area
Wind rose x Not stable Stable
Landscape(farmland / forests) x Not stable Stable
Atmospheric stability conditions x Not stable Stable
Seasonality effect on wind resource is relatively low
on islands in tropical areas
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Specificities of wind climates on tropical islands (3/3)
12 months of measurement is always better than 8 or 10 months for exemple
But . . .
8 or 10 months of measurement on
such area should be enough
To estimate accurately the wind
resource
To allow to get bankable wind
resource assessments
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Conclusions – 1/2
On the one hand….
… A reliable and easy to install (or move)
device for wind measurement
On the other hand…
… A wind climate on tropical islands allowing to
perform an estimate (or a 1st estimate) with less than 12
months of measurements on site
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WIND MEASUREMENTS ON ISLANDS : THE BENEFITS OF USING LIDARS
Conclusions – 2/2
Main applications for using LiDARS on tropical
islands
Standard wind resource assessment studies
Resource mapping
Move one LiDAR on several locations during
few years to carry out a first estimate of wind
resource map
Adjusting meso-cale model on strategic
locations
First estimate of the wind resource on several
islands in the same area
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