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Marine Currents
  Resource
Available Tidal Data
Mapping
Tidal Currents
Velocity Distribution
  Technology
Intro
Hydrodynamics
Horizontal Axis
Vertical Axis
Turbine Theory
Oscillating Foil
Economics

  Environment
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SIF
  Methodology
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Presentation

ESRU Energy Systems Research Unit

University of Strathclyde

  
MARINE CURRENT RESOURCE AND TECHNOLOGY METHODOLOGY

Case Study: Process
    Part 1: Resource Process           Part 2: Technology Matching
Case Study Introduction Case Study Conclusions

Part 1: Resource Process


1. IDENTIFY PROSPECTIVE SITE: Sound of Islay

2. Use ADMIRALTY CHARTS to define:

  • Bathymetry of site and seabed roughness
  • Channel dimensions
  • Nearest diametric ports

5. MAPPING

Generate cross section profile to scale in AutoCAD or similar

Export profile as a bitmap

Colour code surface roughness


6. TIDAL DATA
  • Using tidal spread sheet insert values for:
      • Bathymetry roughness, blockage, meander, irregularity, etc
      • Tidal heights over a period of interest for two diametric ports near to the site
  • Fig: extracted values from easy tide

7. Tidal spreadsheet generates values for:

  • Mean flow rate
  • Optimum turbine energy capture
  • Simultaneous calculation of Manning’s & Bernoulli nos. to yield friction coefficients
    • if desired

8. VELOCITY DISTRIBUTION SOFTWARE

  • Insert coloured bitmap profile into program
  • Insert value for slope in stream direction
  • Insert values generated from tidal spreadsheet

9. GENERATE VELOCITY DISTRIBUTION FOR SITE


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Part 2: Technology Matching

10. Set a 30m depth limit and subtract inoperable areas from the profile:

  • 5m from surface
  • 5m from seabed


11. Using tidal data, generate a frequency distribution over a year of tidal current velocities

12. Find the predominant velocity for the channel profile: 2m/s (from velocity spectral density curve)

13. Find the Cp (efficiency) of each technology and size at the predominant velocity:


14. To calculate the NUMBER of devices that fit into channel.
(This is a function of the area, depth, & number of devices and is limited by the recommended extraction value (SIF))

  • Set spacing distances as follows:
 

15. LOCATE the devices in the appropriate areas of the velocity profile until space is exhausted






Fig: Three different sizes and spacing for each technology inserted into the available space in the profile

16. Calculate the SIF (Significant Impact Factor) with respect to the velocity

  • If SIF limit of 10% is exceeded, recalculate number of devices that can be inserted into channel

17. Calculate the total POWER output over the year using the number of devices, the inflow area, the Cp and the SIF impact on velocity and therefore generate 9 possible options in terms of size, number inserted & power output

16. Assess most suitable technology by considering power output in conjunction with economics & environmental impacts for a particular velocity profile

17. Repeat entire process by considering the power output for another profile the specified distance along the channel

18. Repeat by generating profiles and their potential power outputs along the channel and summing the value to calculate the power output for the entire length of channel

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Case Study Introduction Case Study Conclusions


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