The present paper aims at investigating the efficiency properties of a cylindrical WEC placed in front of a vertical, surface piercing, breakwater of infinite length. A theoretical model is presented based on the linearized velocity potential, the image theory and the matched axisymmetric eigenfunction expansion formulations. The WECs under examination are the heaving absorber and the oscillating water column device. From the present analysis it is demonstrated that the absorbed wave power by the examined WECs in front of a vertical wall is strongly affected by the geometrical parameters of the converters and their mechanical components, and these should be considered when designing the WEC-breakwater system so as to increase its wave power efficiency.


Ocean waves have vast energy potential. However, harnessing the wave power is more complex than the process of converting other renewable energy sources like wind or sun into electricity. Wave conditions (i.e., wave heights and wave frequencies) can vary wildly over time and from an installation location to another. As a result, the wave energy sector is focusing on developing efficient solutions capable to withstand the demanding environmental conditions in the installation areas. In this respect, various Wave Energy Converters (WECs) characterized by different working principles, i.e., modes of power absorption, have been proposed and designed (McCormick, 1981; Pelc and Fujita, 2002; Falnes, 2007) with the oscillating water column devices (OWCs) and the heaving WECs (heaving absorbers) representing the most advanced device types (Magagna, et al., 2016).

To increase the efficiency of a WEC several parameters have been up to date examined. Representative examples are: (a) the optimization of the WEC's geometrical characteristics, in the scope of harnessing maximum wave energy at the installation location; (b) the optimization of the WEC's characteristics with respect to their mechanical components, to withstand the demanding environmental conditions, as well as to reduce the energy losses associated with the transformation of the wave power into electricity; and (c) the installation of WECs close to other near- or on- shore maritime structures such as a breakwater; a harbor or a pier, so as to use the already developed electric grid, reducing in parallel the WECs' environmental impact (Konispoliatis and Mavrakos, 2013; Mavrakos and Konispoliatis 2012; Konispoliatis et al., 2020; Mustapa et al., 2017).

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