Forest Experiments Ferhat Bingöl

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1 Forest Experiments Ferhat Bingöl f bi@ i dt dk febi@risoe.dtu.dk PostDoc Risø DTU 2009

2 Outlook Instruments Experiment Sites Models Results Conclusion Questions 2 Risø DTU, Technical University of Denmark

3 Lidars 3 Risø DTU, Technical University of Denmark

4 ZephIR(s) 4 Risø DTU, Technical University of Denmark

5 How a single wind speed measurement done? A Q U I R E 512 x 256 = SPLIT RAW DATA FFT FFT FFT FFT FFT W I N D AVERAGE ALL SPECTRUMS S P E E D f D FIND THE PEAK Risø DTU, Technical University of Denmark

512 FFT FFT FFT FFT FFT W I N D 256 256 256 256 256 AVERAGE ALL

6 Conical Scanning Mode Original Working Mode of ZephIR u Vr V r 1 round = 1 second 3 rounds give 1 good data It can change focus distance in 1 sec φ=30 o (Azimut angle) H -φ φ l θ=[0:π/2] (scanning angle) 25 points on each height V r = ucos ϕcosθ + vcosϕ sinθ + wsinϕ V = ucosθ + vsinθ + w r Max height = 200m Min height = 10m 6 Risø DTU, Technical University of Denmark

(scanning angle) 25 points on each height V r = ucos ϕcosθ + vcosϕ sinθ + wsinϕ V = ucosθ +

7 Best Case Scenario 7 Risø DTU, Technical University of Denmark

8 Reliability 8 Risø DTU, Technical University of Denmark

9 Removing the wedge With the wedge Without the wedge The wedge from left The wedge 9 Risø DTU, Technical University of Denmark

10 Sites 10 Risø DTU, Technical University of Denmark

11 Forest Sites S Ø R O F A L S T E R 11 Risø DTU, Technical University of Denmark

12 2007: Lille Bøgeskov, Zealand; Mast and Platform 12 Risø DTU, Technical University of Denmark

13 2008: Falster, Zealand; 45m Masts in and out of the forest & lidar up to 100m 13 Risø DTU, Technical University of Denmark

14 Models 14 Risø DTU, Technical University of Denmark

15 WAsP Engineering 2.0 We have applied the idea with three different slope allocation methods at the Falster site (a) by adding a slope in front of the edge, (b) adding a slope half in - half out of the forest and (c) adding a slope completely in the forest. Also different slope angles are applied at each location as 11, 17,23 and 29 degrees 15 Risø DTU, Technical University of Denmark

by adding a slope in front of the edge, (b) adding a slope half in - half out of the forest and

16 SCADIS Grid map Roughness of the terrain Vegetation is defined by the drag forces 16 Risø DTU, Technical University of Denmark

17 Falster: LAD profile 17 Risø DTU, Technical University of Denmark

18 Falster: LAD profile s validation 18 Risø DTU, Technical University of Denmark

19 Falster: LAI uncertainties 19 Risø DTU, Technical University of Denmark

20 Results 20 Risø DTU, Technical University of Denmark

21 Sorø 21 Risø DTU, Technical University of Denmark

22 Sorø 22 Risø DTU, Technical University of Denmark

23 Falster WEST EAST 23 Risø DTU, Technical University of Denmark

24 Falster WEST EAST 24 Risø DTU, Technical University of Denmark

25 Conical Scan bias Field -> Forest Forest -> Field 39m Forest oes -> Field ed 70m Forest mast 100m Field mast & lidar 25 Risø DTU, Technical University of Denmark Field -> Forest

26 Falster WEST 26 Risø DTU, Technical University of Denmark

27 Comments WAsP results are better than WAsP Engineering results. Vector map implementation should be tried on WAsP. SCADIS has bigger promise for fast(er) and reliable forest modelling. The model can be linearised A third mast far out of the forest is needed Mobility of lidar should be used to measure in different positions of the forest. 27 Risø DTU, Technical University of Denmark

28 Conclusions Results show that the mean wind speed calculated by LINCOM flow model is only reliable between 1h and 2h above canopy. This limitation is not acceptable for wind energy site assessments because the typical hub heights for present day wind turbines are above 90 m. The rest of the terms, like wind direction, vertical wind speed and turbulence parameters are unreliable. The SCADIS model reports better correlation with the measurements up to 160 m which is more useful for wind energy applications. Horizontal lidar measurements shows the possibility of more advance forest edge experiments. At the forest edge the LINCOM model is used by allocating a slope half-in half-out of the forest with 17 degree, which is the optimum slope and allocation method observed by the authors. Therefore, authors suggests the use WAsP Engineering for forest edge modelling with this respect and understanding. The SCADIS model works better than the LINCOM model at the forest edge but the model reported better results at upwind than the downwind and this should be noted as a limitation of the model. 28 Risø DTU, Technical University of Denmark

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