A new seawater low-head turbine for the OBREC

OBREC is a wave energy conversion system that utilizes the overtopping phenomenon. It operates by allowing waves to run over a ramp and enter a reservoir located above sea level within a breakwater. The wave energy is then converted into potential energy before being directed through a turbine to generate electrical energy. OBREC prototype is located in Naples harbour, Italy. The primary goal of the pilot project was to demonstrate the system's high-capacity factor, showcasing its ability to generate electricity even in a low-energy wave climate. Over the past 42 years, the average wave power at the site was found to be 1.8 kW/m. The system has proven to be reliable under severe wave conditions, with recorded wave heights exceeding 5 meters in the last five years. In ongoing monitoring activities conducted in real marine environments, a new set of power take-off equipment was installed in 2021, consisting of a propeller-type pico-turbine that was finalized in 2022. The performance and reliability of the entire structure were closely monitored during various stress tests, including start-stop cycles in the marine environment with different combinations of flow rate and hydraulic head. This paper focuses on the OBREC design including the development of the new turbine, task performed by means of numerical simulations. It also deals with the optimization of the hydraulic system and with the control of the electric generator, presenting some field results.