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Wind resources and wind farm wake effects offshore observed from satellite
Charlotte Bay Hasager
Poul Astrup
Merete Bruun Christiansen
Morten Nielsen
Rebecca Barthelmie
Risø National Laboratory, Wind Energy Department
EWEC 2006, Athens 27 February to 2 March 2006
Motivation
Satellite data are complementary to:
offshore in-situ data……….that are costly
offshore model results…….that are not fully verified
EWEC 2006, Athens 27 February to 2 March 2006
1800 km
400 km
100 km
EWEC 2006, Athens 27 February to 2 March 2006
),( ionwinddirectwindspeedfSectionRadarCrossNormalized
PhysicsOcean surface is roughened
by wind interaction such that
capillary and short gravity
waves are generated.
More wind causes
more steep waves that
causes higher backscatter.
EWEC 2006, Athens 27 February to 2 March 2006Courtesy: NOAA
Horns Rev, Elsam A/S
EWEC 2006, Athens 27 February to 2 March 2006
EWEC 2006, Athens 27 February to 2 March 2006
QuikScat Mean wind speed 5 years
Number of observations: 3650 (twice per day for 5 years)
Grid cell:
ca. 25 km
EWEC 2006, Athens 27 February to 2 March 2006
QuikScat North
EWEC 2006, Athens 27 February to 2 March 2006
QuikScat East
EWEC 2006, Athens 27 February to 2 March 2006
QuikScat South
EWEC 2006, Athens 27 February to 2 March 2006
QuikScat West
Weibull A and k per sector in WASP tab-file format available
EWEC 2006, Athens 27 February to 2 March 2006
Wind field from Envisat ASAR WSM (Courtesy: JHU/APL)
Horns Rev, Elsam A/S
EWEC 2006, Athens 27 February to 2 March 2006
EWEC 2006, Athens 27 February to 2 March 2006
EWEC 2006, Athens 27 February to 2 March 2006
Envisat processed at JHU/APL
EWEC 2006, Athens 27 February to 2 March 2006
7
8
9
10
0 50 100 150 200 250
North Distance (km) South
Mea
n w
ind
spee
d (m
/s)
Near coast11 km west
EWEC 2006, Athens 27 February to 2 March 2006From Nielsen et al. 2004, Risø-R-1479(EN)
Horns Rev (Denmark)
5 km
ERS
Mean wind speed for 30 days
Grid cell: 400 m
EWEC 2006, Athens 27 February to 2 March 2006
91 SAR wind maps
Directions from image, LG supervised
U = 7.8 m/s
E = 496 W/m2
Directions from met. mast
U = 7.3 m/s
E = 421 W/m2
Directions from image, LG automatic
U = 7.7 m/s
E = 510 W/m2
In situ measurements (Sommer, 2003):
U = 7.6 m/s
E = 422 W/m2
EWEC 2006, Athens 27 February to 2 March 2006
EWEC 2006, Athens 27 February to 2 March 2006
Wind farm sites
ERS (no wind)
Horns Rev
Offshore Wind Farm
BlaavandshukMet. mast
N
EWEC 2006, Athens 27 February to 2 March 2006
Wind farm
ERS
Horns Rev
Wind farm wake effects
Reduced mean wind speed
Enhanced turbulence
EWEC 2006, Athens 27 February to 2 March 2006
x
y
Y
X
EWEC 2006, Athens 27 February to 2 March 2006
Airborne SAR (E-SAR)
12 October 2003
Wind
Met. mast
5 flight tracks in C-band VV
EWEC 2006, Athens 27 February to 2 March 2006
Winds from E-SAR in CVV
Wind farm Wind farm
Wind Wind
Wind speed Velocity deficit
EWEC 2006, Athens 27 February to 2 March 2006
Christiansen & Hasager (2006), Using airborne SAR for wake mapping offshore. Wind Energy (in press).
EWEC 2006, Athens 27 February to 2 March 2006
Acknowledgements:Danish Research Agency SAT-WIND and SAR-WAKE projects; ESA EO-windfarm and EO-1356 projects;Elsam A/S Meteorological data.
Wind resources can be estimated from satellite wind maps as a supplement to in-situ data.
Wake velocity deficit can be quantified from satellite wind maps.
Conclusions