1. ESRU Development and In-Sea Testing of a Single Point Mooring Supported Contra-rotating Marine Turbine (CoRMaT) Cameron Johnstone Director: Energy Systems Research Unit University of Strathclyde, UK www.esru.strath.ac.uk

2. Technology: Next Generation Tidal Turbine The novel idea behind the contra-rotating turbine concept is to use two closely spaced dissimilar rotors, moving in opposite directions This has several technical and cost advantages over single rotor designs: –Increases relative shaft output speed –Increases the efficiency of energy capture –Eliminates complex blade pitch control –Reduces turbulent flow downstream of the rotors –Minimises reactive torque, thus promising a single point mooring possibility –Increases the dynamic stability of the turbine in the tidal flow Electrical power take off is possible via direct drive of a contra- rotating generator, or by separate generators ESRU

3. Concept Development Hub Phase 1: Tank TestingPhase 2: Rotor Testing Phase 3: System Testing ESRU

4. Phase 1: 1/30 th Scale Turbine Tow-Tank Tests Hub –Rotor performance: Torque/ speed characteristics (power out). Changes in blade pitch angle and rotor spacing. Interaction between rotors. –Structural/ mooring system Dynamic loading due to reactive torque. ESRU

5. 1/30 th Scale Turbine Tow Tank Testing Hub ESRU

6. 1/30 th Scale Turbine Performance ( ) ESRU

7. Phase 2: 1/7 th Scale 2.5m Blades – FEM Design ESRU

8. 1/7 th Scale CoRMaT alongside MV St Hilda Miller Fifer 36’ ESRU

9. 1/7 th Scale CoRMaT Operating Miller Fifer 36’ ESRU

10. 1/7 th Scale Turbine Performance Results are as predicted - within test series. Rotor Dynamics Recorded ESRU

11. Phase 3 Objectives (2008/ 09) To take the proven power capture, wake minimisation and torque cancelling properties of CoRMaT and integrate them into a standalone system that: –Can easily be deployed, maintained, and recovered –Generates electricity from a direct drive alternator –Proves the proposed single-point mooring system Complete financial appraisal of scaling to a full scale system and development of the commercialisation plan. ESRU

12. Phase 3 CRT-2 Schematic Axial Flux Generator Contra-rotating Blades Rear Buoyancy Front Buoyancy To Tether ESRU

13. Direct Drive, Open-to-sea Generator Advantages: –Ease of construction –Nacelle & casing leaks not an issue –Natural cooling –No complex sealing requirement –No large diameter seal friction Disadvantages: –Hydrodynamic effects of rotating generator parts (negligible) –Marine growth potential Axial flux Permanent magnet Ne-Fe-B Rectified 3-phase output ESRU Spine Rotors Ne-Fe-B Magnets Stator Prime Mover 1 Shaft Prime Mover 2 Shaft

14. CoRMaT Test-tank Video ESRU

15. CoRMaT Mooring  Single point tether from either a seabed gravity base or anchors: –ease of installation and retrieval, –low cost, –available proven components, –flexible configuration, tuned for differing depths, tidal climates and seabed composition. –tracking of tidal diamond ESRU

16. CoRMaT System Test Locations 1) Kyles of Bute 2) Sound of Islay ESRU

17. CoRMaT System Test Location 1 Test Site Kyles of Bute Site chosen as: –sheltered, –2.6 knot tide, –easy access, –range of shallow water depths (6 – 10m). ESRU

18. CoRMaT System Testing Installed miniCoRMaT system at slack water Submerged Turbine ESRU

19. Turbine Performance – Stability KoB Stability of device is good – improves under greater loading ESRU

20. Sound of Islay (Visual Impact!) Turbine buoy ESRU Site chosen as: –more energetic, –5.2 knot tide, –water depths (12– 42 m).

21. FFT Analysis of CoRMaT pitch data showing dominant frequencies at Islay PitchFnF1F2F3 Hz0.5971.7923.8858.167 SourceOversize nacelle Fundamental rotor 1 speed Combined rotor speed Karman vortex shedding F2 Fn F1 F3 ESRU

22. FFT Analysis of CoRMaT roll data showing dominant frequencies at Islay ESRU F3 F5 F6 F4 F1 RollF1F4F5F6 Hz1.8599.36235.65747.742 SourceFundamental rotor 1 speed 5*F1PMG stator non uniformitie s (9*F2) Blade- blade interactions (12*F2)

23. CoRMaT Islay Deployment Video at ‘Slack Water !!!’ ESRU

24. CoRMaT: Next Phase, 2010 - University Spin-out Company- Marine Renewables Development Deploy (X) x 250 kW turbines Operate for 1 year and monitor device performance and interactions Option C chosen due to ‘off-the-shelf’ component availability Direct drive 2 x 125 kW gen-sets per device Development and Up-scaling of contra- rotating generator for next phase of deployment (Option D). Now being implemented ESRU G Gearbox G A)A) G Diff. Gearbox B)B) GG C)C) D)D) G Power Take-off Options

25. Conclusion Contra-rotation can produce zero reactive torque, eliminate the need for a gearbox and enable direct drive of a contra- rotating generator. Low cost single point mooring provides station keeping in different tidal stream conditions, without impacting on device performance. Simplified single point mooring system enables quick and easy deployment/ recovery. Considerably reduced system, installation and operational costs attained All IPR belongs solely to the University of Strathclyde with a sole license agreement to the University spinout company. UK (GB2005/161492) and International patents. ESRU