Wind energy in a changing climate

Alexander BakkerKNMIbakker@knmi.nl

ECAM2 October 2009

Decreasing trend wind yield (turbines)

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1988 1993 1998 2003 2008

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Contents

• Geostrophic wind speed as predictor• Past trends (Reanalysis & NAO index)

Offshore wind measurements

Potential wind

Wind turbines (power curve)

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wind speed (m/ s)

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y y

ield

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W)

Nordex N-90 LSVestas V90 3MWVestas V90 2 MWV80 - 2000

Geostrophic wind speed

• ERA40 2.5 x 2.5 1958-2001• ERA Interim 1.5 x 1.5 1989-

R (Windex,geostrophic wind)

ERA Interim ERA40

Windex and ERA interim geostrophic wind

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1989 1994 1999 2004 2009

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WindexERA Interim

Windex and ERA40 geostrophic wind

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1957 1967 1977 1987 1997 2007

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13

Geo

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d (m

/s)

WindexERA InterimERA40

Trends geostrophic wind speed (m/s)/yr

ERA InterimERA40

P-value trends geostrophic wind speed

ERA InterimERA40

Temporal dependency?

ERA40 (5 O.L. 52.5 N.B.)

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0 2 4 6 8 10 12number of years

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theoretical without temperol dependency

sample multiyear standard deviation

ERA40 (2.5 O.L. 57.5 N.B.)

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0 2 4 6 8 10 12number of years

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tion

theoretical without temperol dependency

sample multiyear standard deviation

NAO index

Jones PD, Jonsson T and Wheeler D (1997) Extension to the North Atlantic Oscillation using early instrumental pressure observations from Gibraltar and South-West Iceland. Int. J. Climatol. 17, 1433-1450. 3

Conclusions

• Trends in wind yields are not caused by climatological trends

• Geostrophic wind speed and NAO index are good predictors for “relative” wind yields in the North Sea

• Is there temporal dependency (autocorrelation, persistence)?

What causes the increasing difference?

80

90

100

110

120

130

1989 1994 1999 2004 2009

Win

dex

(%

)

8

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13

Geo

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phic

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d s

pee

d (m

/s)

WindexERA Interim