Category Archives: Resource Characterization

Evaluation of the Wave Energy Conversion Efficiency in Various Coastal Environments


Eugen Rusu – Energies, June 2014

Abstract

The main objective of the present work was to assess and compare the wave power resources in various offshore and nearshore areas. From this perspective, three different groups of coastal environments were considered: the western Iberian nearshore, islands and an enclosed environment with sea waves, respectively. Some of the most representative existent wave converters were evaluated in the analysis and a second objective was to compare their performances at the considered locations, and in this way to determine which is better suited for potential commercial exploitation. Continue reading

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The role of tidal asymmetry in characterizing the tidal energy resource of Orkney


Simon P. Neill, M. Reza Hashemi, and Matt J. Lewis – Renewable Energy, August 2014

Abstract

When selecting sites for marine renewable energy projects, there are a wide range of economical and practical constraints to be considered, from the magnitude of the resource through to proximity of grid connections. One factor that is not routinely considered in tidal energy site selection, yet which has an important role in quantifying the resource, is tidal asymmetry, i.e. variations between the flood and ebb phases of the tidal cycle. Here, we present theory and develop a high-resolution three-dimensional ROMS tidal model of Orkney to examine net power output for a range of sites along an energetic channel with varying degrees of tidal asymmetry. Since power output is related to velocity cubed, even small asymmetries in velocity lead to substantial asymmetries in power output. We also use the 3D model to assess how tidal asymmetry changes with height above the bed, i.e. representing different device hub heights, how asymmetry affects turbulence properties, and how asymmetry is influenced by wind-driven currents. Finally, although there is minimal potential for tidal phasing over our study site, we demonstrate that regions of opposing flood- versus ebb-dominant asymmetry occurring over short spatial scales can be aggregated to provide balanced power generation over the tidal cycle.

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Spatial variability of waves within a marine energy site using in-situ measurements and a high resolution spectral wave model


I. Ashton, J.C.C. Van-Nieuwkoop-McCall, H.C.M. Smith, and L. Johanning – Energy, January 2014

Abstract

A high resolution spectral wave model is used to quantify the spatial wave climate on geographical scales relevant to intra-site variability for marine renewable energy installations. For the first time, results are compared to in-situ data from an array of four floating wave buoys, and demonstrate the ability of the spectral wave model SWAN (Simulating WAves Nearshore) to resolve spatial differences in the wave climate. Examination of the model source terms highlights bottom friction and refraction as the primary processes contributing to the observed differences across the site. Continue reading

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Method for identification of Doppler noise levels in turbulent flow measurements dedicated to tidal energy


Jean-Baptiste Richard, Jim Thomson, Brian Polagye, Jochen Bard – International Journal of Marine Energy, December 2013

Abstract

Acoustic Doppler sensors used for flow measurements at energetic tidal sites present an inherent “Doppler noise” in the measured signal, varying with hardware configuration and flow conditions. At scales comparable to the sensors’ sampling frequencies, the corresponding perturbations notably contaminate the signal, and cannot be corrected in the time series. Continue reading

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Wave and offshore wind energy on an island


M. Veigas, R. Carballo, and G. Iglesias – Energy for Sustainable Development, December 2013

Abstract

The island of Fuerteventura, a UNESCO Biosphere Reserve in the Atlantic Ocean, aims to develop renewable energy sources, in particular wave and offshore wind energy, to reduce its carbon footprint. In this context, the objectives of this work are: (i) to assess the wave and offshore wind resources around the island; and (ii) to determine the area or areas that are best suited for their exploitation, taking into account the resource assessment and other conditioning factors such as the bathymetry, distance to the coastline and ports, and offshore zoning prescribed by the authorities. Continue reading

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Wave resource assessment in Oregon and southwest Washington, USA


Gabriel García-Medina, H. Tuba Özkan-Haller, and Peter Ruggiero – Renewable Energy, April 2014

Abstract

Detailed wave energy resource assessments are necessary for the planning and design of wave energy converters. The waves in the U.S. Pacific Northwest have been identified as very energetic making this coast potentially suitable for wave energy harvesting. Several efforts to harvest this resource are under way in this region, however no long term, high resolution description of the resource is presently available. Here, the results of a 7 year hindcast are presented at a 30 arc-second resolution using the numerical models WAVEWATCH III and SWAN. Continue reading

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On validating numerical hydrodynamic models of complex tidal flow


Kester Gunn and Clym Stock-Williams – International Journal of Marine Energy, November 2013

Abstract

The construction of numerical hydrodynamic models is an important task for offshore renewable energy development, in particular for tidal current farms. An accurate understanding of the spatial variation in resource is necessary for optimally locating fixed measurement devices and turbines, as well as planning site operations.

This work presents a comprehensive methodology for the validation of numerical models in two and three dimensions. First, alternative methods practised in the literature for both time-domain and frequency-domain comparison are assessed and compared. Next, certain novel extended methods are presented for the validation of 3D data, which is not often attempted in the literature. In particular, the shear profiles encountered in real high-velocity sites do not often follow the traditional logarithmic laws, so a new parameterisation is presented and tested.

Finally, acoustic Doppler profiler (ADP) data are analysed and used in a case study validation exercise of a 3D hydrodynamic model of the Fall of Warness in the Orkney Islands, UK. Conclusions are drawn about the validity of the model, as well as the methodology applied.

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A suitable metocean hindcast database for the design of Marine energy converters


Edwige Boudière, Christophe Maisondieu, Fabrice Ardhuin, Mickaël Accensi, Lucia Pineau-Guillou, and Jérémy Lepesqueur – International Journal of Marine Energy, November 2013

Abstract

Resource assessment as well as characterisation of site climatologies for the design of Marine Energy Converters requires data bases allowing an accurate description of the environmental forcing, especially waves and sea-states, on a high resolution grid. As a support to its research activities related to the development of marine renewable energies, Ifremer is building a specific hindcast data set for the assessment of sea-states climatologies. The main features of this database, built running an up-to-date configuration of the WaveWatch III® wave model on an unstructured grid extending from the South of the North Sea to the Bay of Biscay are presented here. Attention is given to the parameterization and forcing as well as the specific output data sets and validation processes.

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Resource Mapping at Tidal Energy Sites


Michael Palodichuk, Brian Polagye, and Jim Thomsom – Oceanic Engineering, July 2013

Abstract

Station keeping, a vessel-based spatial surveying method for resolving details of the hydrokinetic resource, is presented in the context of the general methodology and also for the specific case of a survey conducted in northern Admiralty Inlet, Puget Sound, WA, in June 2011. The acoustic Doppler current profiler (ADCP) measurements collected during the June 2011 survey were part of a broader effort to characterize the resource at this location before tidal turbine installation. Continue reading

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Wave energy conditions in the western French coast


Marta Gonçalves, Paulo Martinho, and C. Guedes Soares – Renewable Energy, February 2014

Abstract

This paper presents a numerical study of the wave energy distribution in the western French coast, in particular in its pilot zone, as part of an European project, aiming to characterize the wave energy in the Atlantic coast of Europe. For this study two third generation state of the art models are used. A generation model, WAVEWATCH III is used to generate waves for the entire North Atlantic basin, so as to properly account for the swell that arrives at the location and a transformation model, SWAN, models the evolution of the waves in the French coast, as a result of wind forcing.

The model results are validated with measured data from three buoys for three-year period between 1998 and 2000. A good agreement was observed between the measurements and the calculated parameters. Descriptive statistics are presented, which give an idea of the variability of the resources.

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