1. Group 4 – Marine Energy Marine Current Modelling For Energy Production James Glynn Kirsten Hamilton Tom McCombes Malcolm MacDonald James Glynn Kirsten Hamilton Tom McCombes Malcolm MacDonald

2. Project Definition Investigate the characteristics of the tidal resources in Scotland and demonstrate how to match those resources with the appropriate Marine current technology

3. Project Flowchart

4. A. Resource Investigation cont…

5. Method and Rationale Define the flow characteristics of a number of sites in the west of Scotland Inadequate tidal current data in the west coast of Scotland  Fails to take into account bathymetry of the area and shear profiles that affect the tidal current flow If shear profile is known for a channel section, velocity, pressure, flow rates and fluxes may be determined Selected a number of sites to identify flow characteristics, using bathymetry and tidal data available to calculate shear profiles using Matlab Bathymetry of areas mapped to generate profiles Tidal velocities for areas calculated to input into modelling program Velocity distributions calculated for an area of a particular characteristic

6. Mapping Methodology

7. Potential High Energy Sites Garred Hassan Marine Resource Report Past Projects DTI Sites Selection Channels or constrictions between islands - fast and rectilinear flow Headlands in the path of moderate flows - best when the headlands are large and do not protrude too sharply into the flow, Estuaries or other resonant water volumes - good sites with rectilinear flow Narrow entrances to enclosed tidal lakes - can have very high currents, but only over a small area. Garred Hassan Marine Resource Report Past Projects DTI Sites Selection Channels or constrictions between islands - fast and rectilinear flow Headlands in the path of moderate flows - best when the headlands are large and do not protrude too sharply into the flow, Estuaries or other resonant water volumes - good sites with rectilinear flow Narrow entrances to enclosed tidal lakes - can have very high currents, but only over a small area. Pentland FirthPentland Firth Orkney IslesOrkney Isles Butt of LewisButt of Lewis Sound of HarrisSound of Harris Barra Sound, South UistBarra Sound, South Uist Barra Head, South UistBarra Head, South Uist Head of ArdmurchánHead of Ardmurchán Tiree & CollTiree & Coll Firth of Lorne, MullFirth of Lorne, Mull Strait of Islay & Jura West Bank IslayWest Bank Islay Middle Bank, IslayMiddle Bank, Islay Kildonan Pt, ArranKildonan Pt, Arran Mull of KintyreMull of Kintyre

8. Mapping Methodology Extrapolate Bathymetry profiles & Seabed Geology Admirality Charts  Bathymetry Contours  Geological & Seabed Data  Surface Roughness  Fisheries, Ports & Ferry Routes Topological Raster – Vector freeware.  Digimap, Easytrace, Wintopo.  Automated Vectorization  Time consuming  Loss of accuracy & Information  Long Clean up Extrapolate Bathymetry profiles & Seabed Geology Admirality Charts  Bathymetry Contours  Geological & Seabed Data  Surface Roughness  Fisheries, Ports & Ferry Routes Topological Raster – Vector freeware.  Digimap, Easytrace, Wintopo.  Automated Vectorization  Time consuming  Loss of accuracy & Information  Long Clean up

9. Mapping Methodology Manual Profiling  Import Selected Site Raster to AutoCAD  Match Admirality Charts & OS Maps Using Scaling Factors.  Apply Appropriate High Resolution Grid  Mark intersecting Contours & Depth Layer  Resulting Profiles  Export as BMP to TOMs Manual Profiling  Import Selected Site Raster to AutoCAD  Match Admirality Charts & OS Maps Using Scaling Factors.  Apply Appropriate High Resolution Grid  Mark intersecting Contours & Depth Layer  Resulting Profiles  Export as BMP to TOMs

10. Mapping Methodology Si – Silt 0.025–0.032 S – Sand. 0.012-0.026 St – Stones/Rock 0.040-0.070 G - Gravel 0.028-0.035 Sh – Shells 0.03-0.04 Wd – Wee/Vegetation 0.025-0.030 Resulting Accurate Surface Bathymetry Model  Defines site depths  Aids accurate current flow characterisation Flow Shear Effects Geological effects on current flow  Manning Coefficient  Surface Roughness  Degree of Meandering  Degree of Irregularity, change of cross section Resulting Accurate Surface Bathymetry Model  Defines site depths  Aids accurate current flow characterisation Flow Shear Effects Geological effects on current flow  Manning Coefficient  Surface Roughness  Degree of Meandering  Degree of Irregularity, change of cross section

11. Calculating Tidal Data Excel tool for general use – available from our website Models distinct tides and calculates resultant phase/tidal flow Output to TOM’s Provision for longer periods modelling Calibration for best fit Comments with instructions Excel tool for general use – available from our website Models distinct tides and calculates resultant phase/tidal flow Output to TOM’s Provision for longer periods modelling Calibration for best fit Comments with instructions

12. Calculating Tidal Data Input data from UKHO’s Easytide prediction service-free Tidal height model = For 2nd port (period shown is 14 days) Subtracting the functions gives the resultant tidal phase Max resultant tidal height = 1.4m @ t = 17.5m Leaves calculations.. Input data from UKHO’s Easytide prediction service-free Tidal height model = For 2nd port (period shown is 14 days) Subtracting the functions gives the resultant tidal phase Max resultant tidal height = 1.4m @ t = 17.5m Leaves calculations..

13. Resultant phase input to calculations:  Inertia, gravity, k-visc principle forces Sensitivity analysis + test on another site  Correlate Bernoulli with friction coeff’?  Bernoulli too big, no friction, arbitrary Values found + equations.  Tide propagation etc.  Venturi effect in channel, ρA1v1 = ρA2v2 + Efr Bernoulli V theoretical = (√ (2g*(∆h))) – Efriction (√ (2* 9.81 *( 1.4))) = 5.42 m/s-1  Must impose a frictional coefficient to correct, but no framework in place, hence cannot be readily applied to different locations Resultant phase input to calculations:  Inertia, gravity, k-visc principle forces Sensitivity analysis + test on another site  Correlate Bernoulli with friction coeff’?  Bernoulli too big, no friction, arbitrary Values found + equations.  Tide propagation etc.  Venturi effect in channel, ρA1v1 = ρA2v2 + Efr Bernoulli V theoretical = (√ (2g*(∆h))) – Efriction (√ (2* 9.81 *( 1.4))) = 5.42 m/s-1  Must impose a frictional coefficient to correct, but no framework in place, hence cannot be readily applied to different locations Initial Results

14. Manning V = (1/n) * R^2/3 * S^½ Hydraulic Radius, R = A/p Where: A = Cross Sectional Area at inlet P = Wetted perimeter, i.e., the distance from high water mark to high water mark along the sea bed: data from mapping exercise, or approx’. Slope, S = h/l Where: H = head difference given by the phase difference, resolved as a gradient over the channel length L = Channel length n taken as 0.025 from manning coefficient guide, also Graham Copeland suggests this value n represents roughness one may associate masonry debris / rubble etc (1/0.0250 * ((42479/4627)^2/3) * ((1.4/9996)^1/2) 40 * 4.384464 * 0.011834 V = 2.07 m/s-1 * 3600 / 1852 = 4 knots Measured average is 3.875 Knots, but this mean spring rate Manning V = (1/n) * R^2/3 * S^½ Hydraulic Radius, R = A/p Where: A = Cross Sectional Area at inlet P = Wetted perimeter, i.e., the distance from high water mark to high water mark along the sea bed: data from mapping exercise, or approx’. Slope, S = h/l Where: H = head difference given by the phase difference, resolved as a gradient over the channel length L = Channel length n taken as 0.025 from manning coefficient guide, also Graham Copeland suggests this value n represents roughness one may associate masonry debris / rubble etc (1/0.0250 * ((42479/4627)^2/3) * ((1.4/9996)^1/2) 40 * 4.384464 * 0.011834 V = 2.07 m/s-1 * 3600 / 1852 = 4 knots Measured average is 3.875 Knots, but this mean spring rate Results

16. Computational Model Main tasks remaining are to verify the results and calibrate model incorporating BL equations for BL growth Capable now of representing vertical and horizontal shear components and through interpolation show distribution in 3D Main tasks remaining are to verify the results and calibrate model incorporating BL equations for BL growth Capable now of representing vertical and horizontal shear components and through interpolation show distribution in 3D

17. Computational Model Main tasks remaining are to verify the results and calibrate model incorporating BL equations for BL growth Capable now of representing vertical and horizontal shear components and through interpolation show distribution in 3D Main tasks remaining are to verify the results and calibrate model incorporating BL equations for BL growth Capable now of representing vertical and horizontal shear components and through interpolation show distribution in 3D

18. B. Technology Investigation

19. Developing a Generic Model of a HAMCT Configuration 1.14m Diameter 2.2 Blades 3.NACA 63-815 4.45° pitch at root, zero at tip, linear variation 5.1m cutout at hub 6.C r =1.2m, C t =0.6m Configuration 1.14m Diameter 2.2 Blades 3.NACA 63-815 4.45° pitch at root, zero at tip, linear variation 5.1m cutout at hub 6.C r =1.2m, C t =0.6m

20. BEM for HAMCT Actuator Disk/Blade Element Momentum Theory for horizontal axis MCT Tempered with Prandtl’s tip loss factor & Glauert correction (based on Spera’s method) Main issue is dynamic pressure drop at top of disk can lead to cavitation Actuator Disk/Blade Element Momentum Theory for horizontal axis MCT Tempered with Prandtl’s tip loss factor & Glauert correction (based on Spera’s method) Main issue is dynamic pressure drop at top of disk can lead to cavitation

21. Efficiency of our HAMCT Maximum η = 30.9% For 2.07ms -1 (4kts) flow at 16rpm  Shaft power 176kW  η = 25% For 3ms -1 flow at 16rpm  Shaft power 711kW  η = 27%

22. NACA 63-815

23. Cavitation Occurs when local pressure drops below vapourisation pressure of fluid Pseudo-vacuum “Bubbles” collapse at sonic velocity Damages surface and reduces performance If σ > (-) C P fluid can vapourise For our turbine in 2.5ms -1 flow at 16rpm σ = 1.65 at tip 5m below surface  tip twist must be so that 2.8 ˚ < α tip < 6.8 ˚ Occurs when local pressure drops below vapourisation pressure of fluid Pseudo-vacuum “Bubbles” collapse at sonic velocity Damages surface and reduces performance If σ > (-) C P fluid can vapourise For our turbine in 2.5ms -1 flow at 16rpm σ = 1.65 at tip 5m below surface  tip twist must be so that 2.8 ˚ < α tip < 6.8 ˚

25. Work in Progress Finish Mapping & Bathymetry Profile Generation  Limiting number of sites of analysis  Focus on requirements of methodology Tidal Flow Velocity Calculation Spread Sheet.  Complete tidal model to output bulk flow velocities in various areas Shear Modelling  Debug & stream line model program for Vertical Shear Component  Generate Accurate Site Velocity Profiles Generic Technology Blade Element Modelling  Input Site Model Velocity Profiles  Output Torque and Potential Power Appraisal of Generic Technology  Vertical & Horizontal Turbines. Oscillating Foils  Oceanographic & Hydrodynamic Suitability of each type  Potential packing densities  Define suitable conditions for each technology in terms of depth, velocity, surface roughness etc Finish Mapping & Bathymetry Profile Generation  Limiting number of sites of analysis  Focus on requirements of methodology Tidal Flow Velocity Calculation Spread Sheet.  Complete tidal model to output bulk flow velocities in various areas Shear Modelling  Debug & stream line model program for Vertical Shear Component  Generate Accurate Site Velocity Profiles Generic Technology Blade Element Modelling  Input Site Model Velocity Profiles  Output Torque and Potential Power Appraisal of Generic Technology  Vertical & Horizontal Turbines. Oscillating Foils  Oceanographic & Hydrodynamic Suitability of each type  Potential packing densities  Define suitable conditions for each technology in terms of depth, velocity, surface roughness etc

26. Environmental impact A number of environmental and governmental considerations and issues have to be taken into account when considering deployment of marine current technology The following agencies have to be contacted when considering a site:  Crown Estates  SNH - Scottish Natural Heritage  SACs - Special Areas of Conservation  SSSIs - Sites of Special Scientific Interest  SEPA - Scottish Environment Protection Agency  Maritime/Coastguard Agency  MOD – Ministry of Defence f A number of environmental and governmental considerations and issues have to be taken into account when considering deployment of marine current technology The following agencies have to be contacted when considering a site:  Crown Estates  SNH - Scottish Natural Heritage  SACs - Special Areas of Conservation  SSSIs - Sites of Special Scientific Interest  SEPA - Scottish Environment Protection Agency  Maritime/Coastguard Agency  MOD – Ministry of Defence f

27. Environmental Impacts There are a number of environmental impacts potentially resulting marine current energy A part of the project is to identify a generic proposal structure that would incorporate the necessary information for all the agencies concerned Potential significant impact issues are:  Seabed/habitat disturbance during construction to marine and intertidal habitats  Navigational risk  collision risk of marine species  Antifouling – need for regular maintenance or antifouling paints  Effect on tidal flow patterns, downstream currents, sedimentation patterns and seabed morphology  Acoustic emissions of the devices and the effect on marine mammals  Visual impacts There are a number of environmental impacts potentially resulting marine current energy A part of the project is to identify a generic proposal structure that would incorporate the necessary information for all the agencies concerned Potential significant impact issues are:  Seabed/habitat disturbance during construction to marine and intertidal habitats  Navigational risk  collision risk of marine species  Antifouling – need for regular maintenance or antifouling paints  Effect on tidal flow patterns, downstream currents, sedimentation patterns and seabed morphology  Acoustic emissions of the devices and the effect on marine mammals  Visual impacts

28. Agencies Crown Estates (CE)  Owns the seabed out to the 12-nautical-mile limit of territorial waters  Any offshore development requires the CE to grant a lease or license over a site. SNH  Provides Government with advice which enables energy policy to take account of natural heritage issues  Impacts of energy use and production  Detailed advice is limited due to early stages of technology development  ‘Outwith areas of high scenic or marine wildlife value, tidal stream generators may offer the potential to generate electricity with lower impacts on the natural heritage than for land-based renewables’  Unfortunately the highest velocity tidal channels are areas of distinct SNH interest  SNH expects impacts on coastal landscapes, marine natural heritage, and seabird populations to be assessed for all types of offshore developments  Still conducting a review of the natural heritage impacts of offshore generators.  Most of the major Scottish estuaries hold internationally important numbers of wildfowl, and contain land or intertidal areas designated as SPAs or SACs SACs  Special Areas of Conservation (SACs) are strictly protected sites designated under the EC Habitats Directive  A number of designated sites are coastal area, large shallow inlets bays and estuaries  Since 2002, the identification of SACs in UK offshore waters has become a part of Joint Nature Conservation Committee’s (JNCC) core work. Crown Estates (CE)  Owns the seabed out to the 12-nautical-mile limit of territorial waters  Any offshore development requires the CE to grant a lease or license over a site. SNH  Provides Government with advice which enables energy policy to take account of natural heritage issues  Impacts of energy use and production  Detailed advice is limited due to early stages of technology development  ‘Outwith areas of high scenic or marine wildlife value, tidal stream generators may offer the potential to generate electricity with lower impacts on the natural heritage than for land-based renewables’  Unfortunately the highest velocity tidal channels are areas of distinct SNH interest  SNH expects impacts on coastal landscapes, marine natural heritage, and seabird populations to be assessed for all types of offshore developments  Still conducting a review of the natural heritage impacts of offshore generators.  Most of the major Scottish estuaries hold internationally important numbers of wildfowl, and contain land or intertidal areas designated as SPAs or SACs SACs  Special Areas of Conservation (SACs) are strictly protected sites designated under the EC Habitats Directive  A number of designated sites are coastal area, large shallow inlets bays and estuaries  Since 2002, the identification of SACs in UK offshore waters has become a part of Joint Nature Conservation Committee’s (JNCC) core work.

29. Agencies SEPA  member of staff currently looking out the relevant information – will call back MoD  Ex-directory! Have e-mailed them though – enquired as to the extent they may require consultation. Maritime & Coastguard Agency  In Scotland and Isle of Man > Northern Lighthouse Board  What concerns might they have?  Navigation primarily.. SEPA  member of staff currently looking out the relevant information – will call back MoD  Ex-directory! Have e-mailed them though – enquired as to the extent they may require consultation. Maritime & Coastguard Agency  In Scotland and Isle of Man > Northern Lighthouse Board  What concerns might they have?  Navigation primarily..

30. Dangers to surface craft Physical Navigation Below 70m, they have no concern Designated testing areas require ok Singular devices Likely require single yellow buoy + flasher Notice to mariners and ref in paper publications Multiple/Farm Mapping of area. Documentation available. However consultation is always case by case. Have authority to say no.. EIS go in with application. Standardised with IALA Recognise requirement for this across board. Helpful and suggested other bodies to consult Dangers to surface craft Physical Navigation Below 70m, they have no concern Designated testing areas require ok Singular devices Likely require single yellow buoy + flasher Notice to mariners and ref in paper publications Multiple/Farm Mapping of area. Documentation available. However consultation is always case by case. Have authority to say no.. EIS go in with application. Standardised with IALA Recognise requirement for this across board. Helpful and suggested other bodies to consult Northern Lighthouse Cont.

31. Next Steps: Complete Resource and Technology Investigation Begin stage 2