A Comparison Study of a Generic Coupling Methodology for Modeling Wake Effects of Wave Energy Converter Arrays (original) (raw)
Related papers
HAL (Le Centre pour la Communication Scientifique Directe), 2012
Wave energy from ocean waves is absorbed by using Wave Energy Converters (WECs). In order to extract a considerable amount of wave power at a location, in a cost-effective way, large numbers of WECs have to be arranged in arrays using a particular geometric configuration. Interactions between the individual WECs ("near field effects") affect the overall power production of the array. In addition, the wave height reduction behind an entire WEC array ("far field effects") may affect other users in the sea, the environment or even the coastline. Several numerical studies on large WEC arrays have already been performed, but large scale experimental studies, focussing on "near-field" and "far-field" wake effects of large WEC arrays are not available in literature. Within the HYDRALAB IV FP7 European programme, the WECwakes research project has been introduced, in order to perform experiments on large arrays of point absorber WECs, using different geometric configurations and inter-WEC spacings. The selected facility is the Shallow Water Wave Basin of the Danish Hydraulic Institute (DHI), in Denmark. The results from the WECwakes experimental tests will be useful in the validation and extension of the recently developed numerical models, as well as in providing insight to optimizing the geometric configurations of WEC arrays for real applications. The latter, also, aims at cost-effective configurations of WEC arrays for power production, and at quantifying the related environmental impact. The present paper focuses on the preparation of the WECwakes project and the development of the used WEC models.
Physical modelling of wave energy converter arrays in a large-scale wave basin: the WECwakes project
Tests have been performed in the Shallow Water Wave Basin of DHI (Hørsholm, Denmark), on large arrays of up to 25 heaving point absorber type Wave Energy Converters (WECs), for a range of geometric layout configurations and wave conditions. WEC response and modification of the wave field have been measured to provide data for the understanding of WEC array interactions and for the evaluation of array interaction numerical models. Each WEC consists of a buoy with a diameter of 31.5 cm and power take-off is modelled by realizing friction based energy dissipation through damping of the WEC's motion. Wave gauges were located within and around the WEC array. Wave conditions studied include regular, polychromatic, long-and short-crested irregular waves. A rectilinear arrangement of WEC support structures has been employed such that several array configurations could be studied. The experimental arrangement and the obtained database are presented. Results have been obtained for power a...
Wave energy from ocean waves is absorbed by using Wave Energy Converters (WECs). In order to extract a considerable amount of wave power at a location, in a cost-effective way, large numbers of WECs have to be arranged in arrays using a particular geometric configuration. Interactions between the individual WECs ("near field effects") affect the overall power production of the array. In addition, the wave height reduction behind an entire WEC array ("far field effects") may affect other users in the sea, the environment or even the coastline. Several numerical studies on large WEC arrays have already been performed, but large scale experimental studies, focussing on "near-field" and "far-field" wake effects of large WEC arrays are not available in literature. Within the HYDRALAB IV FP7 European programme, the WECwakes research project has been introduced, in order to perform experiments on large arrays of point absorber WECs, using different geometric configurations and inter-WEC spacings. The selected facility is the Shallow Water Wave Basin of the Danish Hydraulic Institute (DHI), in Denmark. The results from the WECwakes experimental tests will be useful in the validation and extension of the recently developed numerical models, as well as in providing insight to optimizing the geometric configurations of WEC arrays for real applications. The latter, also, aims at cost-effective configurations of WEC arrays for power production, and at quantifying the related environmental impact. The present paper focuses on the preparation of the WECwakes project and the development of the used WEC models.
2017
Wave Energy Converters (WECs) are devices used to capture ocean energy into useable electricity. In order to produce a large amount of electricity at a competitive cost, arrays composed of large numbers of WECs will need to be deployed in the ocean. Due to hydrodynamic interaction between the WECs (near field effects), the geometric layout of the array is a key parameter in maximizing the overall array power production and minimizing far field array effects on the surrounding area and wave field. Consequently, it is essential to model both the near field and far field effects of a WEC array. Modeling both effects by employing a single numerical model that offers the desired precision at a reasonable computational cost, is, however, still a great challenge.
Renewable Energy, 2019
This research focuses on the numerical modeling of wave fields around (oscillating) structures such as wave energy converters (WECs), to study both near and far field WEC effects. As a result of the interaction between oscillating WECs and the incident wave field, additional wave fields are generated: the radiated and the diffracted wave field around each WEC. These additional wave fields, together with the incident wave field, make up the perturbed wave field. Several numerical methods are employed to analyse these wave fields around WECs. For example, for investigating wave-structure (wave-WEC) interactions, wave energy absorption and near field effects, the commonly used and most suitable models are based on Boundary Element Methods for solving the potential flow formulation, or models based on the Navier-Stokes equations. These models are here referred to as 'wave-structure interaction solvers'. On the other hand, for investigating far field effects of WEC farms in large areas, wave propagation models are most suitable and commonly employed. However, all these models suffer from a common problem; they cannot be used to model simultaneously both near and far field effects due to limitations. In this paper, a generic coupling methodology is presented, developed to combine the advantages of the above two approaches; (a) the approach of wave-structure interaction solvers, which are used to investigate near field effects because they can more correctly model wave energy absorption and the resulting wave fields induced by oscillating WECs or WEC farms. These solvers suffer from high computational cost and thus are mainly used for limited: (i) areas around WECs; (ii) number of WECs, and (b) the approach of wave propagation models, which are used for predicting far field effects and which can model the effect of WEC farms on the wave field and the shoreline in a costeffective manner, but usually cannot deliver high-fidelity results on wave energy absorption by the WECs.
Journal of Renewable and Sustainable Energy, 2015
Wave energy converters (WECs) extract energy from ocean waves and have the potential to produce a significant amount of electricity from a renewable resource. However, large “WEC farms” or “WEC arrays” (composed of a large number of individual WECs) are expected to exhibit “WEC array effects”. These effects represent the impact of the WECs on the wave climate at an installation site, as well as on the overall power absorption of the WEC array. Tests have been performed in the Shallow Water Wave Basin of DHI (Denmark) to study such “WEC array effects”. Large arrays of up to 25 heaving point absorber type WECs have been tested for a range of geometric layout configurations and wave conditions. Each WEC consists of a buoy with a diameter of 0.315 m. Power take-off was modeled by realizing friction based energy dissipation through damping of the WECs' motion. The produced database is presented: WEC response, wave induced forces on the WECs, and wave field modifications have been mea...
A Review of Numerical Modelling of Wave Energy Converter Arrays
Volume 7: Ocean Space Utilization; Ocean Renewable Energy, 2012
Large-scale commercial exploitation of wave energy is certain to require the deployment of wave energy converters (WECs) in arrays, creating ‘WEC farms’. An understanding of the hydrodynamic interactions in such arrays is essential for determining optimum layouts of WECs, as well as calculating the area of ocean that the farms will require. It is equally important to consider the potential impact of wave farms on the local and distal wave climates and coastal processes; a poor understanding of the resulting environmental impact may hamper progress, as it would make planning consents more difficult to obtain. It is therefore clear that an understanding the interactions between WECs within a farm is vital for the continued development of the wave energy industry. To support WEC farm design, a range of different numerical models have been developed, with both wave phase-resolving and wave phase-averaging models now available. Phase-resolving methods are primarily based on potential flo...
Laboratory Observations and Numerical Modeling of the Effects of an Array of Wave Energy Converters
Coastal Engineering Proceedings, 2012
This paper investigates the effects of wave energy converters (WECs) on water waves through the analysis of extensive laboratory experiments, as well as subsequent numerical simulations. Data for the analysis was collected during the WEC-Array Experiments performed at the O.H. Hinsdale Wave Research Laboratory at Oregon State University, in collaboration with Columbia Power Technologies, using five 1:33 scale point-absorbing WECs. The observed wave measurement and WEC performance data sets allowed for a direct computation of power removed from the wave field for a large suite of incident wave conditions and WEC array sizes. Using measured power absorption characteristics as a WEC parameterization for SWAN was developed. This parameterization was verified by comparison to the observational data set. Considering the complexity of the problem, the parameterization of WECs by only power absorption is a reasonable predictor of the effect of WECs on the far field.
2014
An industry standard wave modeling tool was utilized to investigate model sensitivity to input parameters and wave energy converter (WEC) array deployment scenarios. Wave propagation was investigated downstream of the WECs to evaluate overall near-and far-field effects of WEC arrays. The sensitivity study illustrated that both wave height and near-bottom orbital velocity were subject to the largest potential variations, each decreased in sensitivity as transmission coefficient increased, as number and spacing of WEC devices decreased, and as the deployment location moved offshore. Wave direction was affected consistently for all parameters and wave period was not affected (or negligibly affected) by varying model parameters or WEC configuration.