Experimental investigation of a novel adjustable-slope onshore overtopping wave energy converter for coastal protection and energy generation

Wave Energy Converters (WECs) are increasingly being proposed for hybrid coastal infrastructure, offering both renewable energy generation and coastal protection to reduce the high Levelized Cost of Electricity (LCoE) associated with wave energy. Onshore overtopping-type WECs offer a promising pathway to address both challenges by functioning as dual-purpose coastal infrastructure. However, existing designs cannot adapt to seasonal or interannual changes in wave climate due to their fixed geometry. This study experimentally investigates the hydrodynamic performance of a novel onshore overtopping-type WEC featuring an adjustable slope designed to balance energy generation and wave run-up reduction. A series laboratory tests were conducted under regular and irregular wave conditions for three slope angles (20°, 30°, and 37°) to investigate how slope geometry influences wave run-up, overtopping discharge, and hydraulic power potential. The results demonstrate that slope angle is the primary control on the structure’s dual functionality. Gentler slopes produced higher normalized run-up and overtopping discharge, enhancing hydraulic power potential, whereas steeper slopes reduced run-up, providing superior coastal protection. The 20° configuration exhibited the highest overtopping efficiency and power potential, while the 37° slope produced the lowest overtopping. The intermediate 30° slope achieved a balanced response, representing a compromise between energy capture and shoreline protection. The ability to vary slope angle provides an adaptive mechanism to prioritize energy generation under moderate sea states and protection under storm conditions. This study offers a promising proof-of-concept for adaptive, multifunctional coastal structures capable of transforming wave energy from a hazard into a resource.