Scott J. Couch

Tidal current resource assessment

Abstract This paper outlines present thinking on the determination of accessible tidal current resources within channels and other potentially exploitable locations. The fundamental principles behind tides and tidal currents are briefly discussed and the implications of temporal and spatial variations on the evaluation of the resources considered in the context of artificial energy exploitation. The thinking behind the flux approach to resource estimation is presented and an example based on the Pentland Firth is considered. The impact of energy extraction on the flow patterns is considered in both one and two dimensions and the principles required for three-dimensional analyses are presented in a generic form.

Large-scale physical response of the tidal system to energy extraction and its significance for informing environmental and ecological impact assessment

The impact of harvesting tidal energy on the underlying tidal hydrodynamics is examined. Understanding of both the near-and far-field physical response of the tidal system is necessary in order to inform environmental and ecological impact assessment. A number of numerical model test cases are presented which provide first stage indications of the potential response of the system.

Capacity Value of Large Tidal Barrages

This paper presents the first detailed capacity value calculation for tidal barrage generation, based on modeling of operational modes for the proposed 8-GW Severn Barrage scheme in Great Britain. The key finding is that the effective load carrying capability is very low as a percentage of installed capacity (less than 10% for the example presented here). This is because of the high probability of having zero available output at time of peak demand, if peak demand occurs on the wrong part of the tidal cycle; this result may be explained transparently using a simple two-state model of the barrage. The prospects for building a probabilistic model of tidal barrage availability are also discussed.

Environmental impact assessment for tidal energy schemes: an exemplar case study of the Strait of Messina

Tidal currents and ranges in the Mediterranean basin are generally low from a tidal energy perspective. The narrows through the Strait of Messina are an exception, exhibiting intensive tidal currents that have the potential for the economic exploitation. Maximum current velocities at spring peak tides through the Strait vary between 1.8m/s to more than 3m/s. Selection of suitable locations for tidal energy extraction for the exploitation of these natural tidal phenomenon is not, however, a simple process. Constraints must be satisfied, subject to basic criteria dependent upon local factors, technology limitation and economic consideration. In addition, the impact of large scale extraction on the underlying hydrodynamics, environment and ecology within the Strait has to be assessed and evaluated. This paper is a desk-based case study to show how a tidal resource may be environmentally assessed for energy extraction, using the Strait of Messina as an exemplar case

Capacity value of large tidal barrages

This paper presents the first detailed capacity value calculation for tidal barrage generation, based on modeling of operational modes for the proposed 8-GW Severn Barrage scheme in Great Britain. The key finding is that the effective load carrying capability is very low as a percentage of installed capacity (less than 10% for the example presented here). This is because of the high probability of having zero available output at time of peak demand, if peak demand occurs on the wrong part of the tidal cycle; this result may be explained transparently using a simple two-state model of the barrage. The prospects for building a probabilistic model of tidal barrage availability are also discussed.

THE CFD SIMULATION OF A LIFTING HYDROFOIL IN CLOSE PROXIMITY TO A FREE SURFACE

This paper presents results from the CFD simulation of a lifting hydrofoil in close proximity to a free surface. The case considered is that of a NACA 0012 hydrofoil at a Froude number of 0.567. The depth of submergence is approximately equal to the chord length. All results were produced using the commercial CFD code ANSYS-CFX. The primary emphasis of this paper is on the detailed and quantitative verification of the CFD simulations, focussing especially on the spatial discretization and the choice of boundary conditions. Quantitative assessment is by examining the free surface deformation and the lift, drag and moment coefficients. It is found that a very fine mesh (having approximately 1×106 nodes for this 2D case) is required for an accurate prediction of the free surface deformation, whereas a considerably coarser mesh (having approximately 62×103 nodes) gives comparatively accurate prediction of the lift, drag and moment coefficients.Copyright

Tidal Current Energy: Development of a Device Performance Protocol

Development of devices for the exploitation of tidal current energy is reaching the pre-commercialisation phase. In order to equitably test device performance, a standardised procedure for testing is desirable. To meet the remit of the UK government funded Marine Renewable Deployment Fund demonstration scheme, a performance testing protocol was required. This paper discusses the development of, and summarises the requirements of the protocol developed to meet this requirement.

Overview of the SUPERGEN Marine Energy Research Program

An overview of the SUPERGEN marine energy research program is presented. The research program is focussed on supporting the development of marine renewable energy exploitation through generic research to reduce investment risk and uncertainty. Background to the research program, progress to date, and future plans are all summarised.