Investigation of deep sea shelf sandbank dynamics driven by highly energetic tidal flows

© 2016 The Authors In this paper we describe a numerical modelling study carried out to investigate the prevailing sediment dynamics of two large sandbanks located at a site designated for future development of tidal stream energy extraction, in the Inner Sound Channel of Pentland Firth, Scotland, UK. A calibrated and validated 3D Delft3D hydrodynamic model covering Pentland Firth channel was combined with a morphodynamic model. The sea bed changes occurring around the sandbanks during a period of two spring-neap tidal cycles are described and discussed in detail. It was found that both sandbanks, which are located in a deep shelf region (depths>18m), are morphodynamically active and their existence and integrity are strongly linked with the existing hydrodynamic regime

Control strategies for combining local energy storage with wells turbine oscillating water column devices

This paper proposes three generator control strategies for Wells turbine-based floating oscillating wáter column (OWC) devices comprising electrical or mechanical energy storage systems. The first control strategy is indicated for low inertia turbine OWC devices that include ultracapacitors. This control law optimizes the power take-off efficiency by means of an instantaneous speed controller that allows variation of the turbine rotational speed in a wave-by-wave basis. In addition, the profile of the electrical power injected into the grid is smoothed, so that a high penetration of wave energy does not threaten the grid stability. The second and third control laws are developed for OWC systems comprising a flywheel. Quasi-constant and variable speed controllers are proposed. These control laws do not maximize the system efficiency but allow the use of simpler, smaller and cheaper power electronics. Additionally the power quality is also optimized. The development of the proposed control algorithms is accomplished by means of simulations and verified with an experimental test rig.European Commission - MARINET project (Marine Renewables Infrastructure Network) , KIC InnoEnergy through the CIPOWER (Controllable and Intelligent Power Components) projec