Influence of sea-states description on wave energy production assessment (original) (raw)
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Influence of an Improved Sea-State Description on a Wave Energy Converter Production
Volume 5: Ocean Space Utilization; Polar and Arctic Sciences and Technology; The Robert Dean Symposium on Coastal and Ocean Engineering; Special Symposium on Offshore Renewable Energy, 2007
Sea-states are usually described by a single set of 5 parameters, no matter the actual number of wave systems they contain. We present an original numerical method to extract from directional spectra the significant systems constituting of a complex sea-state. An accurate description of the energy distribution is then given by multiple sets of parameters. We use these results to assess the wave climatology in the Bay of Biscay and to estimate the power harnessable in this area by a particular Wave Energy Converter, the SEAREV. Results show that the fine description of sea-states yields a better assessment of the instantaneous device response. The discrepancy between the classical and multi-sets descriptions show that the new one is preferable for the assessment of harnessable power and for device design.
Assessment of the Wave Energy Conversion Patterns in Various Coastal Environments
The main objective of the present work is to assess the performances of various WEC types that would operate in the nearshore. Three different groups of coastal environments were considered. They are: the western Iberian nearshore, two archipelagos (Canaries Islands and Madeira) and the sea environment. The most representative existent wave converters are evaluated in the analysis. In order to estimate the electric power expected in a certain location, the bivariate distributions of the occurrences corresponding to the sea states, defined by the significant wave height and the energy period, were designed in each coastal area. The wave data were provided by hindcast studies performed with numerical wave models or based on measurements. The transformation efficiency of the wave energy into electricity is evaluated via the load factor and also through an index defined as the ratio between the electric power estimated to be produced by each specific WEC and the expected wave power corresponding to the location considered. The work provides valuable information related to the effectiveness of various technologies for the wave energy extraction that would operate in different coastal environments. Moreover, the results can be extrapolated to other areas.
Evaluation of the Wave Energy Conversion Efficiency in Various Coastal Environments
Energies, 2014
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. In order to estimate the electric power production expected in a certain location, the bivariate distributions of the occurrences corresponding to the sea states, defined by the significant wave height and the energy period, were constructed in each coastal area. The wave data were provided by hindcast studies performed with numerical wave models or based on measurements. The transformation efficiency of the wave energy into electricity is evaluated via the load factor and also through the capture width, defined as the ratio between the electric power estimated to be produced by each specific wave energy converters (WEC) and the expected wave power corresponding to the location considered. Finally, by evaluating these two different indicators, comparisons of the performances of three WEC types (Aqua Buoy, Pelamis and Wave Dragon) in the three different groups of coastal environments considered have been also carried out. The work provides valuable information related to the effectiveness of various technologies for the wave energy extraction that would operate in different coastal environments.
Wave energy resource characterisation of the Atlantic Marine Energy Test Site
International Journal of Marine Energy
The Atlantic Marine Energy Test Site (AMETS), a grid connected test area for the deployment of full scale Wave Energy Converters (WECs), is being developed by the Sustainable Energy Authority of Ireland near Belmullet in Co. Mayo, Ireland. In this paper measured data provided by two wave buoys, positioned at a deepwater location (100 m depth) and an offshore location (50 m depth), are analysed in order to characterise the wave resource at the site. In particular, a distinction is made between which sea states occur with the most regularity and which wave conditions are the most significant for the capture of power. The spatial variation in the occurrence of important summary statistics between the deepwater and offshore sites is examined and the difference in incident wave power calculated. Finally, this paper compares conditions at the Belmullet site with those measured at the quarter scale test site in Galway Bay. An assessment on the degree of scalability between resource parameters relevant to WEC power production experienced at the two locations, as recommended by development protocols, is made and methods for comparing benign and exposed sites proposed.
Journal of Coastal Research, 2018
Wave energy is one of the marine renewable energy types, essential to achieve a sustainable development. Coastal countries need to know the wave energy potential along their coasts, so its contribution to the future electricity market is estimated. Spain has noticeable variations in its average wave climate, so it is essential to analyse numerous locations. For research purposes, wave energy potential is estimated based on data from the 15 Spanish State Port buoys currently in operation in deep waters. Because these buoys were set up at different times, with some moored around 2005, the sample between 2005 and 2015 is studied with the purpose of comparing results. REDEXT buoys, arranged from highest to lowest wave energy potential, are: Villano-Sisargas (56.84 kW/m), Cabo Silleiro (53.50 kW/m), Estaca de Bares (53.36 kW/m), Cabo de Peñas (39.66 kW/m), Bilbao-Vizcaya (39.09 kW/m), Gran Canaria (23.71 kW/m), Mahón (16.21 kW/m), Cabo de Begur (13.95 kW/m), Golfo de Cádiz (12.70 kW/m), Dragonera (10.16 kW/m), Cabo de Gata (8.43 kW/m), Cabo de Palos (8.17 kW/m), Tenerife Sur (6.93 kW/m), Tarragona (6.14 kW/m) and Valencia (5.42 kW/m). Some buoys were moored in the 1990s allowing an analysis to be made of how the average wave climate has changed over the last years. Furthermore, a study is undertaken analysing the feasibility of different wave energy converters, specifically Pelamis 750 kW, Oyster 300 kW, Aquabuoy 250 kW, and SSG 20,000 kW, in the 15 buoy locations. Energy production and the capacity factor of all devices for the 15 locations are calculated, obtaining as a result that the most suitable device for all the locations studied is Oyster, and the least suitable is SSG. All the results are shown in different comparative tables and figures, with a summary of the most emphasizing information in each buoy.
Wave Energy Resource Analysis for Use in Wave Energy Conversion
In order to correctly predict and evaluate the response of wave energy converters (WECs) an accurate representation of wave climate resource is crucial. This paper gives an overview of wave resource modeling techniques and applies a methodology to estimate the naturally available and technically recoverable resource in a given deployment site. The methodology was initially developed by the EPRI, which uses a modified Gamma spectrum to interpret sea state hindcast parameter data produced by NOAA’s Wavewatch III. This Gamma spectrum is dependent on the calibration of two variables relating to the spectral width parameter and spectral peakedness parameter. In this study, this methodology was revised by the authors to increase its accuracy in formulating wave length. The revised methodology shows how to assess a given geographic area’s wave resource based on its wave power density and total annual wave energy flux.
Planning and Development of Ocean Wave Energy Conversion
At the beginning of the 21st century, global environmental problems, including global warming, were attracting attention worldwide. In these circumstances, momentum is building across the world for the effective utilization of clean and renewable natural energy sources. The ocean is the world's largest collector and storage medium for solar energy. At the same time, it produces various forms of energy while interacting with the atmosphere. Wave energy is an indirect and condensed form of solar energy. Wave gathers their energy from the wind. Wave gather, store and transmit this energy thousands of kilometers with little loss. As long as sun shines, wave energy will never be depleted. It varies in intensity, but it is available throughout the day and year.
WorldWaves wave energy resource assessments from the deep ocean to the coast
2011
WorldWaves is a global wave and wind climate package developed through EU and industry sponsorship over many years. The offshore data incorporates global hindcast and operational wave and wind data from ECMWF, validated and calibrated with independent satellite and buoy data worldwide. These data, which may comprise full directional wave spectra time series, are used as boundary conditions to the latest version of the SWAN model for calculation of nearshore wave climate parameter and spectral time series and statistics. The WorldWaves methodology was originally developed in the late 1980s as part of a large wave energy resource mapping project being performed by OCEANOR at that time for SOPAC (South Pacific Geoscience Commission) in Fiji for many South Pacific island nations. Based on the WorldWaves global database, Fugro OCEANOR have created various high precision offshore wave energy resource and variability maps. In this paper some of the peculiarities of the global wave energy climate are discussed. Further, areas worldwide exhibiting a stable energy-rich wave climate are pinpointed as are areas with a favourable ratio of extreme to mean annual wave power density, a rough indicator of the economic potential of a site. Use of shallow water models such as SWAN together with short-term in-situ wave measurements (buoys) is generally needed at the feasibility stage for a proposed wave farm. At the pre-feasibility stage, the nearshore mapping of coastal wave energy resources is often required over larger areas (e.g., a country or state) and full SWAN modelling is usually too expensive. An alternative, utilising the offshore WorldWaves data together with nearshore satellite observations is a cost-effective alternative. This method is described © Proceedings of the 8th European Wave and Tidal Energy Conference, Uppsala, Sweden, 2009 and validated against nearshore buoy data on the US West Coast. The package will also be demonstrated live at the conference exhibition to interested parties.
A high resolution geospatial database for wave energy exploitation
Energy, 2014
The estimation of energy production of a given WEC (wave energy converter) at a given coastal site is the basis for correct decision-making regarding wave energy exploitation in a coastal region. Nevertheless, the procedure followed by the conventional approach to characterize the wave energy resource does not provide the required information to obtain an accurate estimate. In this work, this information is provided for the region with the greatest resource in the Iberian Peninsula, the Death Coast (NW Spain). For this purpose, a geospatial database is produced by using a methodology which involves the consideration of virtually the totality of the resource together with the implementation of a high resolution spectral numerical model. In addition, a Matlab-based toolbox called WEDGE (Wave Energy Diagram GEnerator) is implemented to access the database and automatically generate high resolution energy diagrams (or characterization matrices) of the wave energy resource at any coastal location within this region. In this way, a precise computation of energy production of any WEC at any site of interest can now be performed. Finally, the functionality of the database is shown through a case study of a recently proposed wave farm.
Energies
The efficiency of wave energy converters (WECs) is generally evaluated in terms of historical wave conditions that do not necessarily represent the conditions that those devices will encounter when put into operation. The main objective of the study is to assess the historical and near future efficiency and energy cost of two WECs (Aqua Buoy and Pelamis). A SWAN model was used to downscale the wave parameters along the NW coast of the Iberian Peninsula both for a historical period (1979–2005) and the near future (2026–2045) under the RCP 8.5 greenhouse scenario. The past and future efficiency of both WECs were computed in terms of two parameters that capture the relationship between sea states and the WEC power matrices: the load factor and the capture width. The wave power resource and the electric power capacity of both the WECs will decrease in the near future. The load factor for Aqua Buoy will decrease in the entire area, while it will remain unchanged for Pelamis in most of th...