Oscillating Water Columns and Other Types of Wave-Energy Converters

Oscillating water column (OWC) wave energy converters (WECs) are probably the simplest and most promising wave energy converters due to their good feasibility, reliability and survivability in practical wave energy conversions and also regarded as the most studied and developed when compared to other types of the wave energy converters. This research aims to develop a reliable numerical tool to assess the performance of the OWC wave energy converters, particularly in the primary wave energy conversion. In the numerical assessment tool, the hydrodynamics of the device and thermodynamics of the air chamber can be studied separately. However, for the complete dynamic system when a power takeoff (PTO) system is applied, these two dynamic systems are fully coupled in time-domain, in which the PTO can have a simple mathematical expression as the relation between the pressure difference across the PTO (the chamber pressure) and its flowrate through the PTO. And the application of a simple PTO pressure-flowrate relation very much simplifies the complicated aerodynamics and thermodynamics in the air turbine system so the whole dynamic system can be simplified. The methodology has been applied to a generic OWC device and the simulation results have been compared to the experimental data. It is shown that the developed numerical method is reliable in and capable of assessing the primary wave energy conversion of oscillating water columns.

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On the Array of Wave Energy Converters: The Case of the Coaxial-Duct OWC

Volume 11A: Honoring Symposium for Professor Carlos Guedes Soares on Marine Technology and Ocean Engineering ◽

10.1115/omae2018-78022 ◽

2018 ◽

Author(s):

J. C. C. Portillo ◽

J. C. C. Henriques ◽

R. P. F. Gomes ◽

L. M. C. Gato ◽

A. F. O. Falcão

Keyword(s):

Wave Energy ◽

Oscillating Water Column ◽

Economic Activities ◽

Energy Converter ◽

Diverse Range ◽

Wave Energy Converters ◽

Large Size ◽

New Findings ◽

Water Columns ◽

Oscillating Water Columns

This work focuses on the initial performance assessment of an array of coaxial-duct (CD) oscillating-water-columns (owc’s) with potential to be used as multipurpose platform for the creation of value in a diverse range of offshore economic activities. The coaxial-duct owc (CD-owc) is an axisymmetric oscillating-water-column wave energy converter that has been studied for both small-size and large-size applications. This work focuses on buoys of 12 meter diameter distributed in an array of five devices, rigidly attached to each other, to form a cluster of owc’s. The objective of the study is to assess the performance of the array with this configuration and estimate the effect of parameters such as distance between devices, various modes of movements, and other constraints on the overall power output of the array. Results of different cases are compared to the performance of an isolated device to determine the interference effect of other devices. Some results validate previous research conclusions and new findings on the behavior coaxial-duct owc are presented.

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Numerical Assessment of Onshore Wave Energy in France: Wave Energy, Conversion and Cost

Journal of Marine Science and Engineering ◽

10.3390/jmse8110947 ◽

2020 ◽

Vol 8 (11) ◽

pp. 947

Author(s):

Philippe Sergent ◽

Virginie Baudry ◽

Arnaud De Bonviller ◽

Bertrand Michard ◽

Jérémy Dugor

Keyword(s):

Wave Energy ◽

Atlantic Coast ◽

Production Costs ◽

Wave Energy Conversion ◽

Wave Energy Converters ◽

Cost Of Energy ◽

Numerical Assessment ◽

Depth Analysis ◽

Water Columns ◽

Oscillating Water Columns

There are few general analyses of the interest of onshore wave energy converters (onshore WEC) in terms of resources, efficiency and cost. The case of The Channel on the Atlantic coast of France is chosen here to illustrate the issues related to onshore WEC development. The paper presents a list of potential sites with their characteristics and a more in-depth analysis of a few sites. For four onshore WEC families, the production is given with a method of calculating the efficiency and economic analysis is carried out to estimate the energy cost at two selected sites. Annual wave power levels are maximum in Bayonne with 24 kW/m, and the lengths of useful dikes vary from 60 m in Molène up to 4000 m in Cherbourg. Wave reflection on the dike is an advantage in terms of energy production. The oscillating flaps constitute the systems with the highest efficiency, and the float systems have the lowest levelized cost of energy (LCoE), followed closely by the oscillating flaps. Oscillating water columns and overtopping systems have nearly five times these LCoEs. With mass production, costs of oscillating floats and flaps will approach those of other renewable energies such as solar and wind power.

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