Resource assessment for future generations of tidal-stream energy arrays

Abstract

a b s t r a c tTidal-stream energy devices currently require spring tide velocities (SV) in excess of 2.5 m/s and water depths in the range 25e50 m. The tidal-stream energy resource of the Irish Sea, a key strategic region for development, was analysed using a 3D hydrodynamic model assuming existing, and potential future technology. Three computational grid resolutions and two boundary forcing products were used within model configuration, each being extensively validated. A limited resource (annual mean of 4 TJ within a 90 km 2 extent) was calculated assuming current turbine technology, with limited scope for long-term sustainability of the industry. Analysis revealed that the resource could increase seven fold if technology were developed to efficiently harvest tidal-streams 20% lower than currently required (SV > 2 m/s) and be deployed in any water depths greater than 25 m. Moreover, there is considerable misalignment between the flood and ebb current directions, which may reduce the practical resource. An average error within the assumption of rectilinear flow was calculated to be 20 , but this error reduced to~3 if lower velocity or deeper water sites were included. We found resource estimation is sensitive to hydrodynamic model resolution, and finer spatial resolution (<500 m) is required for regional-scale resource assessment when considering future tidal-stream energy strategies.

A Comparison of Numerical Modelling Techniques for Tidal Stream Turbine Analysis

“…Simulation durations typically range from a single tidal cycle to more than a year, with time steps of seconds to minutes and output periods of minutes to hours. Coastal scale modelling typically investigates available resource [27,28] or the impacts of energy extraction on the wider environment for array or inter-array scenarios. Resource modelling is conducted to provide greater spatiotemporal coverage than is achieved with field measurements [29].…”

Experimental Analysis and Evaluation of the Numerical Prediction of Wake Characteristics of Tidal Stream Turbine

“…It is expected that tidal stream devices would be employed in constrained areas where the water depth changes from 1.5 to 3 times the turbine diameters (D) [5,6]. Therefore, it is important to understand the turbine performance and characterise the power output because of the bounding surface by the bed and the free surface, which is different from that in an unbounded flow, as waves and the velocity profile are likely to affect the resource [7,8].…”

Electrical Components for Marine Renewable Energy Arrays: A Techno-Economic Review

“…These are exclusively tidal arrays, as there are no notable array-scale developments of wave energy converters. Although the estimated tidal energy resource is significantly less than the estimated wave energy resource, the predictability of tides presents advantages over other renewable energy technologies [17,18], for both network operators and investors. Furthermore, the vast majority of potential tidal sites in the U.K. are located within 10 km from shore in water depths less than 80 m [19].…”