The effects of array configuration on the hydro-environmental impacts of tidal turbines.

Abstract

Tidal stream turbines provide a technically viable means of generating electricity from a sustainable resource; however, economic viability will require the deployment of multiple devices in array formations in a manner analogous to wind farms. This research investigates the effect of the configuration of a tidal turbine array on the hydro-environmental impacts of the array such as changes in tidal flows and water surface levels. The Shannon Estuary, a highly energetic estuary on the west coast of Ireland with significant potential for tidal current energy extraction, was simulated using a depth integrated 2D hydro-environmental model, namely DIVAST. The numerical model was modified to incorporate the effects of energy extraction on the tidal regime and a multiple device array was simulated. Three different array configurations were examined with turbine spacings of 0.5, 2 and 5 rotor diameters. The model results demonstrate that energy extraction has an attenuation effect on the currents within the array while flow is accelerated around the array. Water surface elevations are also affected with a reduction in tidal range upstream of the array. The magnitude and extent of the observed impacts are greater for the smallest turbine spacing but were still significant for the larger spacings.