A new hybrid type of ocean wave energy extraction system is introduced and numerical investigations of the extraction system are presented in this paper. The system consists of 3 components: floating cylinder, pendulum plates, and fixed vertical support with a function of self-controlling position. Because of a new system, hydrodynamic interaction behaviors due to each component has been not clearly clarified as well as pile-soil interaction due to those. From several parametric analyses of the system on wave and soil conditions, changes in mechanical responses of the system were examined. Before the parametric analysis of pile-soil interaction under hydrodynamic wave loading, numerical tests for ocean wave generation were conducted to verify the numerical wave-maker in the study. Numerical investigations, with respect to changes in the initial soil deformable modulus and the strength of soil, were then conducted. Through this study, it was shown that stresses in the column of the wave energy extraction system increase as the initial soil stiffness and the strength decrease.
Many countries have been paid attention to the ocean wave energy due to its infinite potential and pollution-free characteristics. Generally, wave energy converters (WECs) has low the energy conversion efficiency because ocean conditions are various and sensitively fluctuated over time. Until now, several types of WECs have been designed to enhance the energy conversion efficiency. According to Falcão (2010), WECs can be classified into three types: moving body, overtopping and oscillating water column (OWC) types. These WECs have different conversion mechanisms to generate the electricity, and positive and negative factors for the energy harvesting occur at the same time due to the mechanisms; for example, because the moving body type of WEC is directly exposed to wave, this causes relatively high conversion efficiency, but frequent breakdown. In particular, the existing systems have been experiencing several difficulties for generating the electricity continuously, due to offshore load, wave variability, and sea creatures. Thus, a new type of the wave energy harvesting system has been needed to overcome those difficulties of the conventional system.