Impact of human interventions on tidal stream power: The case of Cádiz Bay

This work quantifies how human interventions can modify the tidal energy potential in a mesotidal estuary and if these variations can be used to increase the production of renewable energy at a highly altered bay. The analysis is applied to Cádiz Bay (Southern Spain), where important human interventions are developing, specifically a new port terminal and a 5 km long bridge. Due to these interventions, significant impacts on the bay hydrodynamics are expected. To assess the variations on the tidal energy resource after interventions, a three dimensional numerical model is used to obtain the bay hydrodynamics (Delft3D model). It was calibrated and validated against water levels and currents at tidal and sub-tidal scales using the results of two extensive field surveys. Two scenarios are defined, corresponding to the pre and post interventions situations. Results show that before interventions, only one area has the potential to locate a Tidal Energy Converter (TEC) array. However, after interventions a new area arise due to the increase of flow velocities induced by human modifications of the bay geometry. The energy potential is assessed for these two locations, and their efficiencies (potential energy per device) are obtained, indicating that after interventions the new TEC array is even more efficient than that of the pre interventions scenario, and an increase of 20% in the energy that can be potentially produced is obtained.