One of the most abundant energy sources exists in this world is the ocean wave energy. By far, it has shown to be the most clean, renewable, predicted energy and has raised the potential to compete with the current use of non-renewable energy sources. Recent research conducted on wave energy invention has opened a new dimension to slowly reduce the dependency on fossil fuel by introducing new technology on the renewable world but relatively lacking in economical aspect. This review brings the latest status on integration of wave energy device with other marine facilities, which is the breakwater structure that may possibly aid to cost sharing. Most researches done on this field highlighted countries experiencing rough sea condition and focused less on countries with medium wave condition as faced by the Asian continent. The potential for energy extraction and wave dissipation for medium wave condition will be discussed in this review by considering several aspects including reliability, effectiveness and performance. Finally, this review shows that the integration opens up a new dimension to acknowledge the technology harnessing ocean wave, especially for the Asian countries experiencing medium wave condition.

Wave energy device and breakwater integration: A review

The 2nd full-scale shoreline Oscillating Water Column (OWC) wave energy device to be constructed in the UK, LIMPET, has been completed on the island of Islay, Scotland. The LIMPET device comprises a rectangular inclined OWC that ducts the generated airflow through two contra-rotating Well’s turbines, each coupled to a 250kW induction generator giving the device a 500kW maximum power output. This paper serves to provide an overview of the LIMPET device from conception to the current status and the initial operational experiences of running the plant.

Overview and Initial Operational Experience of the LIMPET Wave Energy Plant

Comparison of LIMPET contra-rotating wells turbine with theoretical and model test predictions

The Oscillating Wave Surge Converter (OWSC) is a novel shoreline or near-shore wave energy converter. The concept has developed from an analysis of the performance of the LIMPET shoreline oscillating water column. This analysis showed that the hydrodynamics of shoreline wave energy converters are highly non-linear and that they have a qualitatively different response to similar devices that are sited in deeper water. In particular, the water particle motion in shallow water is predominantly horizontal, with elongated wave troughs and heightened wave peaks. The OWSC is designed to couple strongly with the horizontal particle motion, permitting large amplitudes of motion of the working surface whilst minimising energy losses in associated water particle motions. The OWSC consists of a paddle rotating about a horizontal axis above the water surface and perpendicular to the direction of wave propagation. The paddle hangs at the mouth of a gully, effectively forming a 'water column' between the paddle and gully back wall. Thus, the OWSC is similar to the Japanese 'Pendulor' system; however the OWSC uses resonance of the water column rather than harbour resonance as its operating principle. A limited study of geometric parameters using a two-dimensional wave-tank model has been performed. Results from these experiments have shown that the 'water column' has an effect on the paddle dynamics and OWSC performance, with the OWSC having a higher power capture than both a shoreline oscillating water column (OWC) and Pendulor in shallow water. The potential for the OWSC in the shoreline and near-shore regions is also discussed, with implications for construction costs and the price for electricity generated by the OWSC. Potential control strategies for the OWSC are also discussed, together with their likely effect on operation and performance.

The oscillating wave surge converter

Aerodynamic conversion of ocean power from wave to wire

The design, construction and subsequent operation of the 75kW oscillating water column wave power plant on the Isle of Islay has provided a significant insight into the practicality of wave power conversion. The development of wave power plant poses a significant design and construction challenge for not only civil but also mechanical and electrical engineers. The plant mus withstand the immense forces imposed during storms, yet efficiently convert the slow cyclic motion of waves into a useful energy source such as electricity and so so at a price competitive with other forms of generation. In addition, the hostile marine environment hampers the construction process and the variability of the wave resource poses problems for electrical control and grid integration. Many sceptics consider wave power conversion to be too difficult, too expensive and too variable to justify the effort and expense necessary to develop this technology. However, the authors contend that with modular wave power systems developed from the practical experience gained with the Islay plant, wave power is a viable technology is still at the early stages of development and will require the construction of number of different prototypes before there is extensive commercial exploitation.

T.J.T. Whittaker

Papers

The islay wave power project: an engineering perspective.