Wave energy in Italian seas : hydroelectric modeling of a point absorber with a directly driven tubular linear generator

In this work a point absorber wave energy converter, directly driven by a tubular linear generator is designed and modeled. The device consists in a floating body, capturing energy from the incident waves, and a tubular linear generator placed on the sea bottom and connected to the buoy via a rope. The aim of this work is to design and model a device suitable for the Italian wave climates. Eight study sites are considered: Alghero, Mazara del Vallo, Ponza, La Spezia, Crotone, Monopoli, Catania and Ortona. At these sites wave climate data is available from the National wave metric network (RON).The mathematical model of the wave energy converter takes into account the coupling between the hydrodynamic and electromagnetic components. As the wave energy resource shows a strong variability over the Italian locations considered, different generators are designed with a nominal power of 6, 10 and 20 kW. As the electric generator influences the motion of the moving body, several cylindrical buoys are considered for each linear generator. A sensitivity analysis of the influence of the buoy geometry on the power output is carried out. The performance and the electricity production of different buoy-generator configurations is calculated for the eight study sites. The results are synthesized by performance indicators such as annual energy output, capacity factor and capture width. For each study site the most suitable device configuration is determined on the basis of a global performance indicator. Finally, the work explores the possibility to enhance the amplitude response of the device by a passive strategy, which reduces the natural frequency of the system and so allows to achieve the resonance condition.