Power Take Off Damping Optimisation With Regard to Wave Climate

2004 ◽  
Author(s):  
Gaelle Duclos ◽  
Aurelien Babarit ◽  
Alain H. Clement
Keyword(s):  
Wave Energy ◽  
Vertical Motion ◽  
Simple Wave ◽  
Wave Climate ◽  
Optimal Parameters ◽  
Energy Converter ◽  
Wave Energy Converters ◽  
Classical Wave ◽  
Project Site ◽  
Wave Conditions

Considered as a source of renewable energy, wave is a resource which exhibit high variability at all time scales. Furthermore wave climate also changes significatively from place to place. Wave energy converters are very often tuned to suit the more frequent significant wave period of the project site. In this paper we show that optimizing the device necessitates to account for all possible wave conditions weighted by their occurrence frequency, as generally given by the classical wave climate scatter diagrams. Instead of a real device, a generic and very simple wave energy converter was considered here. We show how the optimal parameters can be different considering whether all wave conditions are accounted for or not, whether the device is controlled or not, whether the vertical motion is limited or not. We also show how they depend on the area where the device is to be deployed, by applying the same method to three very different sites.

scholarly journals Optimizing the Power Take Off of a Wave Energy Converter With Regard to the Wave Climate

2005 ◽  
Vol 128 (1) ◽  
pp. 56-64 ◽  
Author(s):  
Gaelle Duclos ◽  
Aurelien Babarit ◽  
Alain H. Clément
Keyword(s):  
Wave Energy ◽  
Simple Wave ◽  
Wave Climate ◽  
Wave Energy Converter ◽  
Optimal Parameters ◽  
Energy Converter ◽  
Wave Energy Converters ◽  
Classical Wave ◽  
Project Site ◽  
Wave Conditions

Considered as a source of renewable energy, wave is a resource featuring high variability at all time scales. Furthermore wave climate also changes significantly from place to place. Wave energy converters are very often tuned to suit the more frequent significant wave period at the project site. In this paper we show that optimizing the device necessitates accounting for all possible wave conditions weighted by their annual occurrence frequency, as generally given by the classical wave climate scatter diagrams. A generic and very simple wave energy converter is considered here. It is shown how the optimal parameters can be different considering whether all wave conditions are accounted for or not, whether the device is controlled or not, whether the productive motion is limited or not. We also show how they depend on the area where the device is to be deployed, by applying the same method to three sites with very different wave climate.

scholarly journals Experimental Investigation of the Mooring System of a Wave Energy Converter in Operating and Extreme Wave Conditions

2020 ◽  
Vol 8 (3) ◽  
pp. 180 ◽  
Author(s):  
Sergej Antonello Sirigu ◽  
Mauro Bonfanti ◽  
Ermina Begovic ◽  
Carlo Bertorello ◽  
Panagiotis Dafnakis ◽  
...  
Keyword(s):  
Wave Energy ◽  
Careful Analysis ◽  
Wave Energy Converter ◽  
Extreme Wave ◽  
Energy Converter ◽  
Correct Operation ◽  
Wave Energy Converters ◽  
Rotational Joint ◽  
Wave Conditions ◽  
The University

A proper design of the mooring systems for Wave Energy Converters (WECs) requires an accurate investigation of both operating and extreme wave conditions. A careful analysis of these systems is required to design a mooring configuration that ensures station keeping, reliability, maintainability, and low costs, without affecting the WEC dynamics. In this context, an experimental campaign on a 1:20 scaled prototype of the ISWEC (Inertial Sea Wave Energy Converter), focusing on the influence of the mooring layout on loads in extreme wave conditions, is presented and discussed. Two mooring configurations composed of multiple slack catenaries with sub-surface buoys, with or without clump-weights, have been designed and investigated experimentally. Tests in regular, irregular, and extreme waves for a moored model of the ISWEC device have been performed at the University of Naples Federico II. The aim is to identify a mooring solution that could guarantee both correct operation of the device and load carrying in extreme sea conditions. Pitch motion and loads in the rotational joint have been considered as indicators of the device hydrodynamic behavior and mooring configuration impact on the WEC.

scholarly journals The Effect of a Wave Energy Farm Protecting an Aquaculture Installation

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2109 ◽  
Author(s):  
Dina Silva ◽  
Eugen Rusu ◽  
C. Guedes Soares
Keyword(s):  
Wave Energy ◽  
Positive Impact ◽  
Wave Climate ◽  
Coastal Protection ◽  
Wave Energy Converters ◽  
The North ◽  
Wave Conditions ◽  
Offshore Aquaculture ◽  
Wave Farm ◽  
The Impact

This paper assesses the impact of a farm of wave energy converters on a nearby offshore aquaculture installation and on the nearshore dynamics. The coastal area targeted is Aguçadoura, located in the north of Portugal, where the world’s first wave farm operated in 2008. The study is focused mainly on the evaluation of the sheltering effect provided by the wave farm to the aquaculture cages. Furthermore, the possible impact on the coastal wave climate of such an energy park is also evaluated. These objectives are accomplished by performing simulations, corresponding to the wave conditions, which are more often encountered in that coastal environment. The SWAN model (Simulating WAves Nearshore) was adopted for this. Various transmission scenarios are considered to account for the impact of different types of wave converter farms on the downwave conditions. The results show that such a wave energy park might have a clear positive impact on the wave conditions fish farm installed downwave and it might also have a beneficial influence on shoreline dynamics from the perspective of coastal protection.

Optimization of Mooring Configuration Parameters of Floating Wave Energy Converters

2011 ◽  
Author(s):  
Pedro C. Vicente ◽  
Anto´nio F. O. Falca˜o ◽  
Paulo A. P. Justino
Keyword(s):  
Wave Energy ◽  
Oil And Gas ◽  
Wave Energy Converter ◽  
Domain Model ◽  
Floating Point ◽  
Mooring System ◽  
Energy Converter ◽  
Energy Devices ◽  
Wave Energy Converters ◽  
Energy Converters

Floating point absorbers devices are a large class of wave energy converters for deployment offshore, typically in water depths between 40 and 100m. As floating oil and gas platforms, the devices are subject to drift forces due to waves, currents and wind, and therefore have to be kept in place by a proper mooring system. Although similarities can be found between the energy converting systems and floating platforms, the mooring design requirements will have some important differences between them, one of them associated to the fact that, in the case of a wave energy converter, the mooring connections may significantly modify its energy absorption properties by interacting with its oscillations. It is therefore important to examine what might be the more suitable mooring design for wave energy devices, according to the converters specifications. When defining a mooring system for a device, several initial parameters have to be established, such as cable material and thickness, distance to the mooring point on the bottom, and which can influence the device performance in terms of motion, power output and survivability. Different parameters, for which acceptable intervals can be established, will represent different power absorptions, displacements from equilibrium position, load demands on the moorings and of course also different costs. The work presented here analyzes what might be, for wave energy converter floating point absorber, the optimal mooring configuration parameters, respecting certain pre-established acceptable intervals and using a time-domain model that takes into account the non-linearities introduced by the mooring system. Numerical results for the mooring forces demands and also motions and absorbed power, are presented for two different mooring configurations for a system consisting of a hemispherical buoy in regular waves and assuming a liner PTO.

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

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.

scholarly journals Loads on a Point-Absorber Wave Energy Converter in Regular and Focused Extreme Wave Events

2020 ◽  
Author(s):  
Eirini Katsidoniotaki ◽  
Edward Ransley ◽  
Scott Brown ◽  
Johannes Palm ◽  
Jens Engström ◽  
...  
Keyword(s):  
Wave Energy ◽  
Wave Train ◽  
Offshore Structures ◽  
Wave Energy Converter ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Energy Converter ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Extreme Loads

Abstract Accurate modeling and prediction of extreme loads for survivability is of crucial importance if wave energy is to become commercially viable. The fundamental differences in scale and dynamics from traditional offshore structures, as well as the fact that wave energy has not converged around one or a few technologies, implies that it is still an open question how the extreme loads should be modeled. In recent years, several methods to model wave energy converters in extreme waves have been developed, but it is not yet clear how the different methods compare. The purpose of this work is the comparison of two widely used approaches when studying the response of a point-absorber wave energy converter in extreme waves, using the open-source CFD software OpenFOAM. The equivalent design-waves are generated both as equivalent regular waves and as focused waves defined using NewWave theory. Our results show that the different extreme wave modeling methods produce different dynamics and extreme forces acting on the system. It is concluded that for the investigation of point-absorber response in extreme wave conditions, the wave train dynamics and the motion history of the buoy are of high importance for the resulting buoy response and mooring forces.

Experimental study on the performance of a floating array-point-raft wave energy converter under random wave conditions

2019 ◽  
Vol 139 ◽  
pp. 538-550 ◽  
Author(s):  
Shaohui Yang ◽  
Hongzhou He ◽  
Hu Chen ◽  
Yongqing Wang ◽  
Hui Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Random Wave ◽  
Energy Converter ◽  
Wave Conditions

scholarly journals A New Solution for Sea Wave Energy Harvesting, the Proposal of an Ironless Linear Generator

2020 ◽  
Vol 8 (2) ◽  
pp. 93 ◽  
Author(s):  
Domenico Curto ◽  
Alessia Viola ◽  
Vincenzo Franzitta ◽  
Marco Trapanese ◽  
Fabio Cardona
Keyword(s):  
Wave Energy ◽  
Magnetic Force ◽  
Vertical Motion ◽  
Small Islands ◽  
Sea Waves ◽  
Energy Converter ◽  
Energy Potential ◽  
Linear Generator ◽  
Three Phase ◽  
Sea Wave

The paper investigates an innovative ironless linear generator, installable inside a wave energy converter, in order to produce electricity from sea waves. This energy source is considered strategic for the future, especially in small islands; however, this technology is still far from the commercial phase. Considering the wave energy potential of the Mediterranean Sea, a first prototype of the electrical linear generator was realized at the Department of Engineering of Palermo University. This machine can be run by a two-floating buoys system, able to produce a linear vertical motion. The main goal of this paper is the investigation of the advantages and the disadvantages of the utilization of steel materials to realize the stator of linear generators. Thus, starting from the prototype, the authors analyzed the effects produced by the replacement of steel in the stator with a non-magnetic material. For comparison, the authors evaluated the amplitude of no-load voltages, using a three-phase connection scheme, and the amplitude of the magnetic force produced by the interaction of magnets with the stator. Both aspects were evaluated through numerical simulations and mathematical models.

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