Optimization of the Wavecat Wave Energy Converter

Abstract

The development of efficient, reliable Wave Energy Converters (WECs) is a prerequisite for wave energy to become a commercially viable energy source. Intensive research is currently under way on a number of WECs, among which WaveCat©—a new WEC recently patented by the University of Santiago de Compostela. In this sense, this paper describes the WaveCat concept and its ongoing development and optimization. WaveCat is a floating WEC intended for operation in intermediate water depths (50–100 m). Like a catamaran, it consists of two hulls—from which it derives its name. The difference with a conventional catamaran is that the hulls are not parallel but convergent; they are joined at the stern, forming a wedge in plan view. Physical model tests of a 1:30 model were conducted in a wave tank using both regular and irregular waves. In addition to the waves and overtopping rates, the model displacements were monitored using a non-intrusive system. The results of the physical model tests will be used to validate the 3D numerical model, which in turn will be used to optimize the design of WaveCat for best performance under a given set of wave conditions.

Study on Wave Overtopping Discharge Affected by Guiding Wall Angle of Wave Dragon Device Using FLOW-3D Software

“…In a reservoir above sea level, an overtopping system collects incident waves of seawater before releasing it back into the water through turbines. Oblique overtopping is a mechanism that describes how overtopping happens slowly when waves pass between the hulls and makes a relatively modest angle with the overtopped structure [29]. Based on the device's current wave condition (H_s, T_p) and freeboard crest Rc (ramp crest height above mean water level, MWL), water overtopping into the pool (Q_overtop).…”

Physical Modelling of the Effect on the Wave Field of the WaveCat Wave Energy Converter

“…The focus of this article the WaveCat, with the concept drawing shown in Figure 1, is an offshore, floating WEC operating on the principle of oblique overtopping to collect water [35,36]. Waves impinge at an angle along its inner hull before cascading into reservoirs.…”

Laboratory Tests in the Development of WaveCat

“…The device was kept at a constant starting freeboard of 200 mm throughout all tests to establish a benchmark with which to begin the optimisation of the device. Previous proof of concept work [27][28][29] used a freeboard of 40 mm, reducing to 30 mm at the aft reservoir. As tests progress and tanks collect overtopping water the device freeboard will naturally vary therefore the device was expected to behave differently for each value of H s as smaller values would result in fewer waves during a test that could breach the freeboard threshold and overtop.…”

“…Following initial tests of a 1:30 model [27][28][29] a new version of the WaveCat model was built at the University of Plymouth at the same scale, Figure 2, for extended tests. The main dimensions of the model are length of 3 m, height of 0.6 m and maximum width of 0.4 m. The main section of the model was manufactured from aluminium, with the tanks and top mounted wave deflector fabricated from polypropylene sheet.…”