R&D highlights edition 2019

PROJECTS Delta infrastructure A n array of five tidal turbines was installed in the Eastern Scheldt Storm Surge Barrier in 2015. A range of research projects were initiated to investigate the impact of these turbines and to investigate the environmental impact of tidal energy extraction. The research questions were addressed as part of two research projects: DMEC (Dutch Marine Energy Centre) and OTP (Oosterschelde Tidal Power). Working with DelftUniversity of Technology and Tocardo (the turbine manufacturer), Deltares investigated the flow changes near the turbines. Other partners such as Utrecht University, Wageningen Marine Research and Imares focused on the impact of the tidal turbines on sea mammals. The combination of all the research provides us with an integral picture of the environmental impact of the tidal turbines. Large-scale and detailed hydraulic models were developed to investigate all these effects. The large-scale effects in the Eastern Scheldt were assessed with the Delft3D and WAQUA models, while nearfield flows close to the turbines were assessed with CFD simulations. Validation of those simulations on the basis of the available flows (before and after installation), power and thrust measurements showed that the numerical models accurately predicted the flow behaviour, power and thrust of the turbines. The models were used to analyse the impact on bed protection and the change in the discharge through the storm surge barrier. The tools developed during the studies were therefore adequate for an assessment of the impact of tidal turbines on flow velocities and turbulence, which are areas of concern for Rijkswaterstaat. The models and measurements showed that the effects of the tidal power plant in Gate Roompot 8 (operating in a limited head difference condition of -60/+80 cm) are fairlymild. To assess the impact of the turbines for an operational head difference of -90/+90 cm, additional simulations will be required to confirm that the barrier is not exposed to even the lowest risk. In addition to an assessment of the upscaling of the present tidal power plant to larger head differences, the hydraulic tools can also be used for the new tidal power plant that will be installed in Gate Roompot 10 and for the tidal power plant that could be built in the Brouwersdam. Contact: Anton de Fockert, Anton.deFockert@deltares.nl t +31 (0)6 469 111 71 Arnout Bijlsma, Arnout.Bijlsma@deltares.nl, t +31 (0)6 469 111 59 Further reading : O’Mahoney et al. (2019) Hydrodynamic impact and power production of tidal turbines in a storm surge barrier, EWTEC conference 2019 (submitted) 46 An array of five tidal turbines was installed in the Eastern Scheldt Storm Surge Barrier in 2015. A range of research projects were initiated to investigate the impact of these turbines and the environmental impact of tidal energy extraction. Tidal turbines in the simulations Flow patterns near the turbines for a head difference of 32 cm at low tide ENVIRONMENTAL IMPACT OF TIDAL POWER IN THE EASTERN SCHELDT STORM SURGE BARRIER