1. RESOURCE ASSESSMENT AT TURBINE TEST SITE (SEA SCHELDE) TIDAL TURBINE PERFORMANCE ESTIMATION TURBULENT PROPERTIES OF THE FLOW RELATIONSHIP WITH POWER PRODUCTION WAKE EVALUATION AND MAPPING Alexei Sentchev, PhD Lab. Oceanography & Geosciences, Wimereux, France

2. In situ measurements in the Sea Scheldt Joint analysis of flow variability and power generated by W2E turbine Water to Energy

3. Survey I - experimental settings

4. Survey IV Survey III – vel. profiling by towed ADCP Survey II - experimental settings ADCP ADV

5. Current speed > 1m/s at the pontoon location (red square). Velocity is higher (1.3m/s) 50 m northward Velocity profiling by towed ADCP across the Sea Scheldt: flood flow on 18/3/2015 Current profiling, mapping, resource assessment Streamwise velocity (m/s)

6. Power density along a cross-section P  200-250 W/m2 during flood flow on both sides of the pontoon Patchiness in power distribution

7. Time series of along-stream (upper panel) and cross-stream (lower panel) velocity during the second survey (velocities are 10 min averaged) Space-time variability of the f low Streamwise velocity (Oct 2014) Streamwise velocity (Nov 2014) Current ellipses at different depth levels

8. Depth averaged (dashed line) and surface layer (1 m thick) velocity (grey line). Red/blue lines – EbbFlood flow Mean f low properties Ebb flow velocity is 30% higher than flood flow velocity. The choice of tidal period for power production is not justified. Cumulative distribution of V Distribution of V: ebb/flood flow, surf/depth

9. Survey 1: Turbulent intensity Time (h) Ebb tideFlood tide Turb Intensity

10. 8/11/2014 00:00-12:00 Power estimation vs velocity measurements Power curve is far from saturation (higher production rate is possible) Strong power increase for rotation speed > 37 tr/min Two regimes of power production: for higher (>0.9 m/s) and lower flow speed

11. CHECK AGAIN P_measured should higher than 1100W Power estimation vs velocity measurements 7/11/2014 12:00-24:00

12. Estimation of the tidal turbine performance where 7-Nov8-Nov9-Nov Cp0.21 0.250.21 0.200.21 Velocity range (m/s) 0.2 - 1.40.4 - 1.40.2 - 1.5 Comparison of IMDC and LOG vel data

13. Turbulence and power generation by W2E turbine 8.4h Significant change in velocity Peak velocity Curent reversal Turbulence intensity Velocity time series recorded by ADV

14. Power fluctuation (%) versus measured power 7-Nov pm Power fluctuations 8-Nov am 8-Nov pm

15. Turbulence and power generation by W2E turbine Power: raw data After spike removal Power generation statistics Spectra for Power fofo 4f o fofo -5/3 (cf. Fernandez-Rodriguez et al., 2014) 8-Nov-2014 9-Nov-2014

16. Turbulence and power generation by W2E turbine Coherency spectrum 4f o

17. Concluding remarks Field studies are necessary for assessing the flow potential and finding the best location for energy conversion devices In situ measurements provide the background conditions of the flow and could be used as initial condition in numerical modeling Measurements provides estimates of the turbulent properties of the flow – of primary importance for development, testing and modeling Measurements allow estimating the tidal turbine performance with high degree of confidence

18. Ongoing work: assessing and mapping the wake Free drifting system with high frec profiling and high precision velocity recording. All measurements are geolocalized. Under-water localization is possible!