ABSTRACT
The objective of this study is to discuss the hydrodynamic performance of a wave energy converter using floating panels. A scale model was built in the laboratory at Hohai University, and then was employed to investigate the performance of developed wave energy device. In the physical model, the water surface fluctuation, motion of floating panels and the voltage output of the dynamos are simultaneously measured. Wave reflection coefficient and the energy output can be estimated directly using these measurements. Experimental results show that the present device is effective in controlling the wave energy and reducing the threat to the coastal area. When subjected to longer waves, the average output power and conversion efficiency of the WEC can be up to 0.65 W and 2.73%, respectively. Moreover, it is found that the load of the energy device should be carefully designed to match the local wave climate, in order to obtain the best energy conversion efficiency.
Water waves in the ocean hold enormous potential for pollution-free electricity generation and hydrogen production (Clement et al., 2002) It is favored by more and more people due to its wide distribution and other merits. As of now, hundreds of patents have been issued to harness the wave energy or improve WECs' performance (Falcão, 2010; Bahaj, 2011). According to the location, these devices can be classified to either shoreline, nearshore, or offshore ones (Cruz, 2008). Among those categories, shoreline devices have been developed since the early stage of WEC research due to the convenience for installation and maintenance as they are usually fixed or embedded in the shoreline. Meanwhile, the shoreline WECs are chosen also because they are close to the utility network and have good survivability under extreme weather.
Over the years, abundant researches have been carried out on the development of shoreline WECs and some of them have progressed significantly with a promising energy conversion, e.g., Limpet (Alcorn and Beattie, 1998), Seawave Slot-Cone Generator (Vicinanza and Frigaard, 2008), and Tapchan (Tjugen, 1995). However, due to the relatively high costs compared to fossil energy, shoreline wave power devices are still some way from commercialization. To make the cost of wave energy conversion more competitive, kinds of solutions have been proposed and studied in recent years. Among them, one remarkable choice is to combine WECs with other coastal structures, such as sea walls and breakwaters, which may share construction and maintenance costs and avoid extra sea area fees. For example, Huang et al., (2011) investigated the oscillating water columns inside a U-tube which is built on a floating platform in laboratory tests. The moving water inside the U-tube is utilized to extract wave power with the help of a generator when the floating system is subjected to regular waves. Similarly, Peng et al. (2011) presented a WEC making use of the waveinduced motion of a Floating Breakwater (FB). A series of physical model experiments were carried out to verify the practicability and reliability of the proposed device. In addition, Peng et al. (2018) proposed a float-type shoreline wave energy converter coupled with a breakwater. The configuration and hydrodynamic performance of the WEC was discussed via an experimental manner and the developed WEC is proved to be effective in dissipating the incident wave energy, especially for longer waves, and be able to extract wave energy at a meaningful rate from regular waves. More recently, Zhao et al. (2019) proposed an integrated breakwater-WEC system, which was composed of an array of heaving oscillating buoy and a fixed breakwater. Detailed experiments were undertaken to investigate the heave-responseamplitude operator, the wave force on the WEC devices and the transmission coefficient of the breakwater-WEC system.
