Environmental impact of tidal power in the Eastern Scheldt Storm Surge Barrier

The research questions have been adressed in the framework of the research projects: DMEC (Dutch Marine Energy Centre) and OTP (Oosterschelde Tidal Power). Together with the TU Delft and Tocardo (turbine manufacturer), Deltares investigated the changed flow behaviour near the turbines, while other partners like the university of Utrecht, WMR and Imares focussed on the impact of the tidal turbines on sea mammals. The combination of all research gives an integral view on the impact of the tidal turbines on the enviroment.

To be able to investige all these effects, large scale and detailed hydraulic models were created. The large scale effects in the Eastern Scheldt have been assessed by the use of Delft3D and WAQUA models, while the nearfield flow behaviour near the turbines has been assessed by means of CFD simulations. These simulations have been been valided against the available flow (prior and after installation), power and thrust measurements. This validation showed that the numerical models were able to accurately predict the flow behaviour, the power and the thrust of the tubines. With these models, the impact on the bed protection and the change in discharge trough the Storm Surge Barrier was analysed.

So the tools developed in the investigations were adequate to address the impact of tidal turbines on the various aspects of flow velocities and turbulence for which Rijkswaterstaat expressed its concern. The models and measurements showed that the effects of the tidal power plant in Gate Roompot 8 (operating under a limited head difference condition of -60/+80 cm) are fairly mild. To assess the impact of the turbines for an operational head difference of -90/+90 cm, additional simulations are required to confirm that there is not the smallest risk involved for the barrier.

Besides an assessment on the upscaling of the present tidal power plant to larger head differences, the hydraulic tools can be used as well for the new tidal power plant that will be installed in Gate Roompot 10 and for the tidal power plant that might be built in the Brouwersdam.