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Velocity Distribution
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Vertical Axis
Turbine Theory
Oscillating Foil
Economics

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SIF
  Methodology
Intro
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Presentation

ESRU Energy Systems Research Unit

University of Strathclyde

  
MARINE CURRENT RESOURCE AND TECHNOLOGY METHODOLOGY

Methodology: Part 1 -Resource Analysis
    Rationale    Flowchart    Tools   
Methodology Introduction Technology Analysis

Rationale

The objective of PART 1 of the methodology is to analyse the potential resource at the selected site.

As mentioned in the introduction to this section, the entire methodology is based on recognising and defining the specific characteristics of the site in terms of its:

  • Bathymetry
  • Tidal current velocity
  • Seabed roughness.

These factors have a direct influence on the technology selected for the site. The bathymetry alters the tidal current flow at a site as it influences the effects of horizontal and vertical shear. The bathymetry also limits the type of technology that can be used at a site due to the terrain and depth at a site. Some technologies are better suited to shallower or deeper areas, or constricted or open areas. The type of technology can also be affected by the quality of the seabed, whether is is sandy , rocky or covered in vegetation.

The distribution and magnitude of velocity also directly influences the technology chosen and the power it is able to produce. Devices are also rated with respect to their generator size. A device device, due to economic factors, is not able to operate over the entire range of velocities available at the site, and generation begins only after the flow velocity has reached a certain threshold. The values that determine the technology chosen and their power ratings are dictated by the tidal current velocity at the site and its variation over the year.

Therefore the link between the velocity distribution, bathymetry and the seabed roughness must be established to ensure that the technology chosen will be the most appropriate for that site and has the best combination of efficiency, power output and economic factors.

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Flowchart

The following flowchart defines the process that is necessary to establish the velocity distribution for a particular site. The procedure is a manual process that relies on two particular tools, the 'Tidal Current Spreadsheet' and the 'Velocity Distribution Software'. The tools can be substituted if the developer has access to more effective resources, but the main object is to derive a 2D velocity distribution at a particular site.

The procedure to analyse the resource is demonstrated in the case study in the process section.

Tools for Resource Analysis

Click on the icon  to access each tool and click the title to access the 'explanation and theory' behind each tool.

 
   

This tool is used to used to calculate the mean velocity flow bewteen two ports:

  • Resultant Phase of tidal heights provides an energy gradient.
  • UKHO EasyTide gives port tidal heights & admiralty surface flow data
  • Cyclic bulk flow velocity can be calculated
  • Corrected Flow, Meander, Surface Friction, Venturi effects
  • Energy Loss. Manning Vs Bernoulli
  • Turbine enrgy capture and optimal deployment
 
   

This tool is used to quickly assess the effect the topography of a site affects the flow velocity.

  • Insert calculated values for surface flow and roughness coupled with Manning’s equation
  • Software generates a 2D velocity profile that evaluates the influence of :
    • Bathymetry of the site
    • Horizontal and vertical shear
    • Seabed roughness



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Methodology Introduction Technology Analysis


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