Tidal turbine environmental impact and decision-making for shoreline management
Tidal stream energy is considered to be a very promising renewable alternative to traditional fossil fuels. However, there is a large gap in our understanding of the impacts of tidal stream energy devices, despite the growing interest in tidal stream energy exploitation.
Aiming to predict large scale impacts of tidal turbine farms, the current module, turbulence module, wave module and the sediment transport module of the Finite-Volume, primitive equation Community Ocean Model (FVCOM) are modified to simulate turbines in motion. The retarding force concept is employed in the current module, working as an additional body force exerted on the water to simulate the turbine induced water deceleration. Three terms are added into the MY-2.5 turbulence closure to model turbine related turbulence generation, dissipation and turbulence length-scale interference. The built-in feature ‘OBSTACLE’ of the wave module is used to simulate the reduction of wave height caused by the turbine. The enhanced sediment suspension due to the turbine in motion is represented by an additional bottom shear stress term, entraining an extra portion of sediment particles from the bed into the water. The system is tested against comprehensive measurements in a water flume experiment and results of Computational Fluid Dynamics (CFD) simulations. Upon the satisfactory choices of the coefficients, the platform is applied to a 15m scale idealized single turbine case as well as a regional scale case based on the realistic hydrodynamics off the Anglesey coast, north-west of Wales.
With regard to shoreline management, a brief introduction of a study is given, looking at how particulate-bound radioactive contaminants deposited on the salt marsh within the Ribble estuary redistribute under different marsh erosion and future climate scenarios.