Development of an Innovative Hybrid Renewable Energy System for Coastal Protection at the Downdrift End of the Cotonou Groin Field

International audience Coastal erosion at the downdrift end of the Cotonou groin field threatens shoreline stability, infrastructure, and coastal activities in Benin. This study develops a preliminary conceptual design for a hybrid coastal-protection system integrating a submerged breakwater, a wave energy converter (WEC), a photovoltaic (PV) installation, and a hydraulic sediment-pumping unit for artificial beach nourishment. Representative wave, sediment, and solar-resource parameters for the eastern Cotonou coastline were compiled from available studies and applied in simplified engineering calculations. Under the adopted assumptions, the WEC generated an estimated 38.56 kW for a 5 m effective capture width, whereas the pumping unit required approximately 6.05 kW at a discharge of 0.05 m³/s and a 5 m head. The PV array, comprising 10 m² of panels with 17% efficiency, produced an estimated 8.84 kWh per day. The calculated WEC output therefore exceeds the hydraulic power demand under the selected design conditions, while the PV component may provide complementary energy during periods of reduced wave activity. However, its daily energy yield does not independently demonstrate continuous pump operation. The proposed concept links wave attenuation, renewable-energy conversion, and managed sediment redistribution within one coastal-protection framework. The assessment remains preliminary and requires site-specific hydrodynamic and morphodynamic modelling, structural-stability analysis, seasonal energy-yield simulation, storage design, environmental assessment, economic evaluation, and field validation before technical viability or operational effectiveness can be established.