Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays (original) (raw)
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Analysis of the Impacts of Wave Energy Converter Arrays on the Nearshore Wave Climate
This study analyzes the impacts of offshore Wave Energy Converter (WEC) arrays on far-field waves and on nearshore wave-induced hydrodynamic forcing for a variety of array designs and incident wave conditions. The main objective of the study is to provide general conclusions on the nearshore impacts of WEC arrays in order to facilitate the assessment of future field test sites. The study utilizes the spectral wave model SWAN. Two array configurations are simulated, and WEC arrays are located either 5, 10, or 15 km offshore. Input conditions include parametric JONSWAP spectra with a range of offshore wave heights and periods. Trials are conducted with a directional wave field with the dominant direction being shore normal in all cases. Arrays are represented in SWAN through the external modification of the wave spectra at the device locations based on an experimentally-determined Power Transfer Function. Based on an analysis of existing field data, a new threshold for nearshore hydrodynamic impact is also established. The threshold represents an empirical relationship between radiation stress and longshore current magnitude. This threshold value is subsequently used as an indicator of when significant changes in the nearshore forcing are induced by WEC arrays. Results show that the changes in nearshore forcing parameters decrease as the distance between the array and the shore increases. Additionally, a more significant change in nearshore forcing parameters is seen in cases with larger input wave heights and periods and with low directional spread. The incident wave conditions, array configurations, and array locations that lead to nearshore impact are identified and assessed.
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.
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.
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.
2014
A modified version of an industry standard wave modeling tool was evaluated, optimized, and 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 wave direction and WEC device type were most sensitive to the variation in the model parameters examined in this study. Generally, the changes in wave height were the primary alteration caused by the presence of a WEC array. Specifically, WEC device type and subsequently their size directly resulted in wave height variations; however, it is important to utilize ongoing laboratory studies and future field tests to determine the most appropriate power matrix values for a particular WEC device and configuration in order to improve modeling results.
A review of hydrodynamic investigations into arrays of ocean wave energy converters
arXiv (Cornell University), 2015
Theoretical, numerical and experimental studies on arrays of ocean wave energy converter are reviewed. The importance of extracting wave power via an array as opposed to individual wave-power machines has long been established. There is ongoing interest in implementing key technologies at commercial scale owing to the recent acceleration in demand for renewable energy. To date, several reviews have been published on the science and technology of harnessing ocean-wave power. However, there have been few reviews of the extensive literature on ocean wave-power arrays. Research into the hydrodynamic modelling of ocean wave-power arrays is analysed. Where ever possible, comparisons are drawn with physical scaled experiments. Some critical knowledge gaps have been found. Specific emphasis has been paid on understanding how the modelling and scaled experiments are likely to be complementary to each other.
Wave Energy Converter (WEC) Array Effects on Wave Current and Sediment Circulation: Monterey Bay CA
2014
The goals of this study were to develop tools to quantitatively characterize environments where wave energy converter (WEC) devices may be installed and to assess effects on hydrodynamics and local sediment transport. A large hypothetical WEC array was investigated using wave, hydrodynamic, and sediment transport models and site-specific average and storm conditions as input. The results indicated that there were significant changes in sediment sizes adjacent to and in the lee of the WEC array due to reduced wave energy. The circulation in the lee of the array was also altered; more intense onshore currents were generated in the lee of the WECs. In general, the storm case and the average case showed the same qualitative patterns suggesting that these trends would be maintained throughout the year. The framework developed here can be used to design more efficient arrays while minimizing impacts on nearshore environments.
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...
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.