Energies 2013, 6(2), 696-716; doi:10.3390/en6020696
Article

Wind Farm Wake: The Horns Rev Photo Case

Charlotte Bay Hasager 1,* email, Leif Rasmussen 2 email, Alfredo Peña 1 email, Leo E. Jensen 3 email and Pierre-Elouan Réthoré 1 email
1 Technical University of Denmark, DTU Wind Energy, Risø Campus, Frederiksborgvej 399, 4000 Roskilde, Denmark 2 Retired Senior Meteorologist from Danish Meteorological Institute, Lyngbyvej 100, 2100 København Ø, Denmark 3 DONG Energy, Kraftværksvej 53, 7000 Fredericia, Denmark
* Author to whom correspondence should be addressed.
Received: 3 November 2012; in revised form: 21 January 2013 / Accepted: 25 January 2013 / Published: 5 February 2013
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Abstract: The aim of the paper is to examine the nowadays well-known wind farm wake photographs taken on 12 February 2008 at the offshore Horns Rev 1 wind farm. The meteorological conditions are described from observations from several satellite sensors quantifying clouds, surface wind vectors and sea surface temperature as well as ground-based information at and near the wind farm, including Supervisory Control and Data Acquisition (SCADA) data. The SCADA data reveal that the case of fog formation occurred 12 February 2008 on the 10:10 UTC. The fog formation is due to very special atmospheric conditions where a layer of cold humid air above a warmer sea surface re-condensates to fog in the wake of the turbines. The process is fed by warm humid air up-drafted from below in the counter-rotating swirl generated by the clock-wise rotating rotors. The condensation appears to take place primarily in the wake regions with relatively high axial velocities and high turbulent kinetic energy. The wind speed is near cut-in and most turbines produce very little power. The rotational pattern of spiraling bands produces the large-scale structure of the wake fog.
Keywords: wind farm wake; cloud; fog; satellite; met-ocean conditions; wake model 

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MDPI and ACS Style

Hasager, C.B.; Rasmussen, L.; Peña, A.; Jensen, L.E.; Réthoré, P.-E. Wind Farm Wake: The Horns Rev Photo Case. Energies 2013, 6, 696-716.

AMA Style

Hasager CB, Rasmussen L, Peña A, Jensen LE, Réthoré P-E. Wind Farm Wake: The Horns Rev Photo Case. Energies. 2013; 6(2):696-716.

Chicago/Turabian Style

Hasager, Charlotte B.; Rasmussen, Leif; Peña, Alfredo; Jensen, Leo E.; Réthoré, Pierre-Elouan. 2013. "Wind Farm Wake: The Horns Rev Photo Case." Energies 6, no. 2: 696-716.

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