Wave power

About: Wave power is a research topic. Over the lifetime, 2671 publications have been published within this topic receiving 41439 citations. The topic is also known as: wind wave energy & sea wave energy.

On the Dynamics of Wave-Power Devices

Abstract: The performance of a class of wave-power devices is studied theoretically by generalizing the known theory of ship dynamics with which there is good agreement with experiment. The extensions to the existing theory introduce the new features of asymmetry and articulation common to many proposed wave energy convertors. Results are presented for two different devices and a comparison is made between them. The performance calculations correlate very well with the available experimental evidence and moreover it would appear that the two types of device considered in this paper are comparable in their potential operating efficiencies if appropriate scales are chosen. The Salter duck and a two-pontoon system, semi-elliptical in cross section and hinged at its centre, constrained to move only in the mode in which energy is absorbed, appear to be equivalent. Both structures are designed such that when forced to move in their absorbing mode they generate waves in one preferred direction, the pontoon design relying on the use of a shallow horizontal breakwater in the rear of the moving structure whereas Salter has used a shorter deeper structure which looks almost cylindrical. When optimally loaded with a simple velocity-proportional damping applied externally, the performance of each system looks almost identical, with the pontoon being slightly better at the low frequency end. This parity is interesting and more general systems where the structures are free to move in many degrees of freedom must be examined. The reasons for this are apparent from calculated sea efficiencies of the devices. For the duck with a fixed centre and reactive loading, a 10 m diameter device may achieve an excellent performance over typical sea states, but if simple (velocity proportional) loading is used the diameter must increase to 15 m to give a comparable performance. If, however, the structure is free to move in other modes of motion with the same simple loading, then to achieve similar performance characteristics the structure has to be 30 m in diameter. Similar effects are found for the pontoon. Whereas an 80 m long two-pontoon system with a fixed rear section and simple loading will match to the sea conditions very well, a freely floating system with the same loading would need to be 120 m long to achieve a reasonable performance.

Free vibration and wave power reflection in Mindlin rectangular plates via exact wave propagation approach

Abstract: Reflection, propagation and energy analysis are crucially important in designing structures, especially plates. A thick plate is considered based on first order shear deformation theory. Wave Propagation Method (WPM) is employed to exactly derive resonant frequencies and wave power reflection from different classical boundary conditions. Firstly, the frequency results are compared with other literature to validate the exact proposed wave solution in the present work. Then, wave analysis and benchmark results for natural frequencies are presented for six different combinations of boundary conditions. The results indicate that the wave power reflection of thick rectangular plates is quite complicated and an incident wave of a specific type gives rise to other types of waves except for simply supported boundary conditions where the reflected wave power does not depend on the system parameters.

Evaluating the future efficiency of wave energy converters along the NW coast of the Iberian Peninsula

Abstract: The efficiency of wave energy converters (WECs) is generally evaluated in terms of historical wave conditions that do not necessarily represent the conditions that those devices will encounter when put into operation. The main objective of the study is to assess the historical and near future efficiency and energy cost of two WECs (Aqua Buoy and Pelamis). A SWAN model was used to downscale the wave parameters along the NW coast of the Iberian Peninsula both for a historical period (1979–2005) and the near future (2026–2045) under the RCP 8.5 greenhouse scenario. The past and future efficiency of both WECs were computed in terms of two parameters that capture the relationship between sea states and the WEC power matrices: the load factor and the capture width. The wave power resource and the electric power capacity of both the WECs will decrease in the near future. The load factor for Aqua Buoy will decrease in the entire area, while it will remain unchanged for Pelamis in most of the area, except north of 43.5° N. The capture width and cost of energy will increase for both devices. The methodology here applied can be easily applied to any device and coastal domain under different climate change scenarios.

The parameterization of wave-particle interactions in the Outer Radiation Belt

Abstract: We explore the use of mean-value empirical wave models in diffusion models of the Outer Radiation Belt. We show that magnetospheric wave power is not normally-distributed in time and that geomagnetic activity does not provide a deterministic proxy for the temporal variability of wave activity. Our findings indicate that current diffusion models significantly overestimate the action of wave particle interactions due to extremely low frequency and very low frequency waves in the magnetosphere. We suggest that other techniques such as stochastic parameterization will lead to a better characterization of sub-grid diffusion physics in the Outer Radiation Belt.