Toward best practice in the design of tidal turbine arrays

In recent years, much research has focused on the possibility of using arrays of turbines to generate clean and predictable power from tidal currents. The first such array is now in development but a number of important questions remain unanswered. Among these, how should turbines be arranged within a tidal stream to maximise their collective performance? And what impacts will such devices have on the marine environment? In beginning to address these questions, this thesis takes two important steps toward establishing best practice in the design of tidal turbine arrays. In the first part of the thesis, the social and ecological impacts of marine energy development are reviewed. This review highlights the importance of communication and public engagement in securing support for a marine energy project and identifies the effects of increasing noise and collision risk on marine life as the most pressing ecological issues to be addressed. In the second part, theoretical models of tidal turbines are examined and a simple numerical model is used to extend existing theories on optimal turbine arrangement. The shallow water equations are used to simulate flow through an idealised channel and an actuator disc model is used to represent a single row of tidal turbines as a line sink of momentum. Optimal turbine arrangements are then sought for different and increasingly realistic flow conditions. Results provide new and important insights into the dynamics of flow through partial-width arrays and suggest that arranging turbines unevenly within the flow cross-section can increase considerably their collective power output