Use of investor-accepted regional-scale hydrodynamic modelling software to estimate tidal stream energy resources and effects of resource exploitation

Abstract

Regional-scale numerical hydrodynamic modelling is increasing in importance for estimating the tidal stream energy resource that is available in any given location, and for predicting the environmental effects of exploiting that resource. However, the state-of-the-art models that are commonly used in academia are not always trusted by investors or regulators, and are hence of limited value to commercial site developers. In this work two commercially-available modelling suites that are widely used in industry — MIKE and Delft3D — are used to simulate the effects of tidal farms in the Pentland Firth, Scotland. The optimum methodology with each software package is explored, and their predictions compared. It is concluded that they are suitable for the broad-scale predictions for which they are intended, but should not be relied upon alone for fine detail. A flaw is identified in the approach to tidal turbine representation at very high resolutions, relating to the estimation of upstream velocity, which leads to inaccuracy of up to 15%. A correction is implemented and tested. A similar approach in a third model code, FVCOM, is used to estimate the power available from the Goto Islands, Japan, and to study the interactions of parallel channels when energy is extracted. It is found that the multiple channels in Goto do not behave in the same way as the multiple channels of the Pentland Firth, and a possible explanation for this is discussed. Finally, the techniques developed in earlier chapters are combined in the development of a new MIKE 3 model of Lashy Sound, Orkney, and the use of this to estimate the maximum theoretical power yield from this channel.