A hierarchy of approaches for the optimal design of tidal turbine farms

From conception to construction, the process by which tidal turbine farms are scoped and designed (and even optimised – which is the focus here) is multi-layered. The industrial designer requires tools of varying fidelities working on multiple scales, depending on the task at hand. In this paper a hierarchy of modelling approaches is proposed and some examples demonstrated. For site-scoping and resource assessment, the continuum approach enables multiple farms to be considered and optimised over a large geographic area. This is demonstrated for four farms in the Pentland Firth, Scotland. For detailed design, three-dimensional CFD codes allow flow around a turbine to be fully resolved and the physical processes closely modelled. In between, and informed by these extremes, are array design tools whereby each turbine is individually represented and the flow over the domain is calculated with the non-linear shallow water equations. In a test example, the positions of 78 turbines in a farm located in the Inner Sound of the Pentland Firth, Scotland is optimised with a resulting 25% improvement in power extracted. A holistic approach to the design process is also presented which seeks to design with the maximisation of developer’s profit – rather than power extracted as the ultimate goal. Keywords; Tidal farm optimisation, farm design, computational modelling, tidal turbines.