Category Archives: Resource Assessment

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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Spatial Multi Criteria Analysis For the Determination of Areas with High Potential Wave Energy


K. N. Abdul Maulud, W. H. M. Wan Mohtar, and O. A. Karim – Jurnal Teknologi, December 2013

Abstract

The strategic geographical location of Malaysia, with at least 60% of its shores are bordered with ocean, has high potential to sustain the country’s energy supply by harnessing energy from wave. However, the oceans stretch of which is suitable for wave energy generation needs to be accurately determined, with the sensitive and protected areas are taken into account. This study describes the methodology and more developed approach to determine the area not only with high wave energy but also its legality. Continue reading

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Estimate of the tidal stream power resource of the Pentland Firth


Scott Draper, Thomas A.A. Adcock, Alistair G.L. Borthwick, and Guy T. Houlsby – Renewable Energy, March 2014

Abstract

The Pentland Firth is arguably the best-known candidate site for tidal stream power extraction worldwide. In this paper we estimate the maximum power that can be extracted by placing tidal stream power devices across the Pentland Firth and/or the individual sub-channels formed by the islands of Swona, Stroma and the Pentland Skerries. Using a depth-averaged numerical model, for the entire Firth we find that approximately 4.2 GW of power may be extracted, and this agrees reasonably well with predictions from an existing theoretical model. In contrast, for the sub-channels there is no single value to describe the power potential, but rather a range of power estimates because the extracted power from one sub-channel depends on the operation (or otherwise) of tidal devices placed in parallel sub-channels, or in series along the Firth. Continue reading

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Power extraction from tidal channels – Multiple tidal constituents, compound tides and overtides


Thomas A.A. Adcock and Scott Draper – Renewable Energy, March 2014

Abstract

Many candidate sites for tidal stream power extraction are tidal channels, and the power that can be generated from these sites will be directly related to the amplitude and phase of the principal tidal constituents driving flow through the channel. This paper investigates this interaction between energy extraction and tidal constituents, and also the effect that power extraction may have on harmonics of the principal constituents (i.e. compound tides and overtides). Continue reading

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Wave energy resource assessment for a breakwater-integrated oscillating water column plant at Porto, Portugal


J.C.C. Henriques, J.J. Cândido, M.T. Pontes, and A.F.O. Falcão – Energy, November 2013

Abstract

The objective of this paper is to present the wave energy resource assessment having in view the construction of an OWC (oscillating water column) to be integrated into a new breakwater at the mouth of the Douro River in Porto (northern Portugal). The paper starts with the evaluation of the offshore wave energy resource from measured data. This is followed by the wave transformation from offshore conditions to the plant location in about 11 m water-depth. Such transformation was carried out using an inverse-ray refraction model that is described in detail. As expected, the wave power level is lower, whereas the wave energy period is higher, at the plant coastal site as compared with deep water conditions. The average wave direction rotates from approximately NW offshore to nearly West at the plant location, and the directional spread becomes smaller, which are effects of refraction as the waves propagate in waters of decreasing depth.

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Assessment of the impacts of tidal stream energy through high-resolution numerical modeling


V. Ramos, R. Carballo, M. Álvarez, M. Sánchez, and G. Iglesias – Energy, November 2013

Abstract

When planning the installation of a tidal farm, the disturbances on the marine environment associated with its operation must be studied in detail. The objectives of this paper are to assess the impacts on the hydrodynamics (water level and flow velocity) and to determine how these impacts can alter the tidal resource. For this purpose, a high-resolution model of Ria de Ribadeo (NW Spain) is used to describe the potential effects resulting from the operation of two prospective tidal farms. Two different scenarios of extracted power from the flow (high and low) are analyzed. Overall, it is found that the impact on the water level is negligible, but that on the flow velocity is significant. The velocity is reduced upstream and downstream the farm, and increased beside it. These effects are enhanced in the scenario with the higher power extraction. Finally, these modifications in the flow pattern alter the available energy density at the tidal turbine, with a reduction of 21% and 12% for the high and low levels of power extraction, respectively.

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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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Wave electricity production in Italian offshore: A preliminary investigation


Silvia Bozzi, Renata Archetti, and Giuseppe Passonic – Renewable Energy, February 2014

Abstract

In this paper the feasibility of wave energy exploitation off the Italian coasts is investigated. At this aim, the energy production and the performance characteristics of three of the most promising and documented wave energy converters (AquaBuOY, Pelamis and Wave Dragon) are estimated for two of the most energetic Italian locations. The sites are Alghero, on the western coast of Sardinia and Mazara del Vallo, on the Sicily Strait and they have respectively an average annual wave power of 10.3 kW/m and 4 kW/m, and an available annual wave energy of 90 MWh/m and 35 MWh/m. Continue reading

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The Impact of Tidal Stream Turbines on Circulation and Sediment Transport in Muskeget Channel, MA


Aradea R. Hakim, Geoffrey W. Cowles, and James H. Churchill – Marine Technology Society Journal, August 2013

Abstract

The Finite-Volume Community Ocean Model (FVCOM) is configured to evaluate the potential impact of the proposed Muskeget Tidal Energy Project on circulation and sediment transport in the surrounding region. The extraction of tidal kinetic energy from the water column is modeled by augmenting the momentum equations with additional drag terms parameterized using local flow velocities and parameters specific to the installed turbine farm. Model-computed power output compares well with estimates based on velocities derived from a shipboard acoustic Doppler current profiler (ADCP). Total extracted power from the proposed installations during a spring ebb tide represents roughly 9% of the natural power in the deep section of the channel and 30% of the natural tidal dissipation in the turbine installation region. Due to this low level of extraction, turbine installations at the proposed transects result in relatively minor differences in the tidal current magnitude (2.5%), water level (0.8%), sediment flux (0.6%), and bed level (9%). Computations also indicate that the proposed installation generates minimal impacts to the tidal harmonics (3.3% change in amplitude and 1-min delay in phase) and tide-induced depth-averaged residual currents (2.8%). Model-computed extraction at increased levels is associated with greater perturbations to the natural conditions.

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Theoretical Assessment of Ocean Current Energy Potential for the Gulf Stream System


Xiufeng Yang, Kevin Haas, Hermann M. Fritz – Marine Technology Society Journal, August 2013

Abstract

The Gulf Stream system features some of the fastest and most persistent currents in the Atlantic Ocean and has long been identified as a promising target for renewable ocean current energy. This study investigates the theoretical energy potential of ocean currents for the Gulf Stream system. A simplified analytical model is calibrated and utilized to represent the quasi-geostrophic balance in the North Atlantic subtropical circulation. The effect of turbines is included in the model as additional turbine drag force. The energy equation in the system is derived and analyzed both locally and basin-wide. Basin-wide, energy production from surface wind stress is balanced by energy dissipation from natural friction and turbines. However, the pressure gradient is playing an important role in redistributing the energy in the local energy balance. It is found that increasing turbine drag does not necessarily increase total energy dissipation from turbines. The maximum energy dissipation by turbines is estimated to be approximately 44 GW, although electrical power output will be significantly reduced due to various engineering and technological constraints. The turbine drag has significant impact on the circulation system. The reduction of energy and volume fluxes in the circulation is featured for different levels of turbine drag. It is found that residual energy flux along the western boundary can be significantly reduced under the peak energy dissipation by turbines, while reduction of volume flux is less extreme.

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