Monthly Archives: June 2012

Energy extraction from ocean currents and waves: Mapping the most promising locations


A Ordonez Undergraduate, Arizona State University, June 2012


Abstract
Concerns about fossil fuel supplies and an ever-increasing demand for energy have prompted the search for alternative power sources. One option is the ocean, a power-dense and renewable source of energy; but its capacity to meet human energy demands is poorly understood. While raw wave energy resources have been investigated at many scales, little is known about where and how much power can be extracted. Even less is known about the energy available in ocean currents, especially on a global scale. This study assessed where significant amounts of energy in ocean waves and currents are available for human use. Global wave and current energy were calculated from model data and mapped. To assess the recoverable energy around the United States, population and marine protected area data were combined with technical specifications for the Pelamis and SeaGen energy convertors, and the dollar values of the energy were estimated. The results suggest that promising amounts of wave and current energy are available both globally and around the United States. Potential locations for wave and current energy farms appear to exist on the Pacific, Atlantic, and Gulf Coasts of the U.S. Further research in this area may lead to greater support for developing, testing, and deploying ocean energy converter technology.

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Multi-arrayed tidal current energy farm and the integration method of the power transportation


CH Jo, KH Lee, JH Lee, C Nichita – 2012 International Symposium on Power Electronics, Electrical Drives, Automation, and Motion, June  2012

Abstract
Ocean energy resources are attractive renewable supply options for Korea being surround by ocean. Also having very strong tidal current speeds, there are many suitable sites for the application of TCP (Tidal Current Power) on the west and south coastal region in Korea with the maximum current speed of up to 6.5m/s. Not like other renewable energy sources, TCP is the high reliable and predictable and continuous energy source as the current pattern and speed can be predicted throughout the year. Since the large scale tidal current farm consists of many units of the turbine devices, the interaction effect is very important in power production. Also the power integration method in ocean energy has of very important issue. In this paper, the interaction effect and the power connection methods for each turbine unit and the integration method for 200MW tidal current farm are conceptually introduced with the offshore power integration platform

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An overview of hydraulic systems in wave energy application in China


D Zhang, W Li, Y Lin, J Bao – Renewable and Sustainable Energy Reviews, September 2012

Abstract
Wave energy is being increasingly regarded in China as a major and promising resource. There are many different ways to convert wave energy to electricity and some other energy. Hydraulic systems are used most widely in some of them to realize this conversion. An overview of hydraulic systems in wave energy application as well as the relevant technologies in China is given in this article. Some basic principles are presented, assessment and advices are shown for each category. Some suggestions of the outlook of hydraulic systems in wave energy application are also given.

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Modeling Waves in Open Coastal Areas and Harbors with Phase-Resolving and Phase-Averaged Models


E Rusu, CG Soares – Journal of Coastal Research, June 2012

Abstract
A wave-prediction system based on spectral models was validated against in situ measurements in the Portuguese continental nearshore and is now operational. As a final extension of this system, the present article describes the implementation and validation of high-resolution wave models. In this connection, the objective of the present work was to evaluate the performance of such models in different coastal environments. The first target was an open coastal area located in the central part of the Portugal continental. An evaluation of the two state-of-the-art phase-resolving wave models, REFDIF1 and FUNWAVE, was carried out, and the results are compared with those from a field experiment. The second target area was the port of Leixões in the north of the Portuguese continental coast. A high-resolution SWAN computational domain that included the harbor area, was implemented and connected to the modeling system that provides ocean forcing. To provide a more realistic picture of the wave conditions inside the harbor area, the FUNWAVE model was also coupled to the wave-prediction system. Comparisons between the results provided by the two wave models provide a better image of the reliability and limitations of both models at the entrance and inside the harbor area.

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Filed under Modeling, Resource Characterization

Wave energy converter control by wave prediction and dynamic programming


G Li, G Weiss, M Mueller, S Townley, MR Belmont – Renewable Energy, June 2012

Highlights
► We investigate constrained optimal control of sea wave energy converters. ► The objective is to maximize energy take-off while minimizing the risk of damage. ► The optimal control problem is analyzed using Pontryagin’s minimum principle. ► Dynamic programming is employed to resolve the on-line optimization problem. ► Simulation result shows at least a two-fold increase in energy output.

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Synchronized control of cross-flow-water-turbine-based twin towers


M Vallet, I Munteanu, AI Bratcu, S Bacha, D Roye – Renewable Energy, June 2012

Highlights
► A system composed of cross-flow-water-turbine-based twin vertical towers is studied. ► The angular position synchronization of the two towers is ensured by control action. ► This approach is similar to the phase-locked loop techniques used in electronics. ► Real-time experiments on a power hardware-in-the-loop simulator have been carried out. ► The results sustain the reliability and effectiveness of the approach.

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Filed under Instrumentation, System Development

Modeling Waves in Open Coastal Areas and Harbors with Phase-Resolving and Phase-Averaged Models


E Rusu, CG Soares – Journal of Coastal Research, June 2012

Abstract
A wave-prediction system based on spectral models was validated against in situ measurements in the Portuguese continental nearshore and is now operational. As a final extension of this system, the present article describes the implementation and validation of high-resolution wave models. In this connection, the objective of the present work was to evaluate the performance of such models in different coastal environments. The first target was an open coastal area located in the central part of the Portugal continental. An evaluation of the two state-of-the-art phase-resolving wave models, REFDIF1 and FUNWAVE, was carried out, and the results are compared with those from a field experiment. The second target area was the port of Leixões in the north of the Portuguese continental coast. A high-resolution SWAN computational domain that included the harbor area, was implemented and connected to the modeling system that provides ocean forcing. To provide a more realistic picture of the wave conditions inside the harbor area, the FUNWAVE model was also coupled to the wave-prediction system. Comparisons between the results provided by the two wave models provide a better image of the reliability and limitations of both models at the entrance and inside the harbor area.

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Filed under Modeling, Resource Characterization

Experimental study of interactions between multi-directional focused wave and vertical circular cylinder, Part I: Wave run-up


J Li, Z Wang S Liu – Coastal Engineering, June 2012

Highlights
► We studied the multi-directional focused wave run-up on a vertical cylinder. ► We investigated the impacts of wave parameters on the wave run-up. ► The focused wave run-up increased as wave steepness, frequency bandwidth increased. ► A unidirectional wave can generate larger wave run-up than a multidirectional wave. ► The wave parameters also impacted the wave run-up distribution around the cylinder.

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Filed under Modeling

Modelling the economic impacts of 500MW of wave power in Ireland


JP Deane, G Dalton, BPÓ Gallachóir – Energy Policy, June 2012

Highlights
► We modelled the Irish Electricity Market in 2020 with and without 500 MW of wave energy. ► The inclusion of wave energy did not have a significant impact on system marginal prices. ► The inclusion of wave energy reduced total costs in the system relative to a wind only scenario. ► REFIT tariff remains an essential financial support for the nascent wave energy industry.

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Filed under Economics

Calibration and Validation of a FAST Floating Wind Turbine Model of the DeepCwind Scaled Tension-Leg Platform


GM Stewart, MA Lackner, AN Robertson, J Jonkman, A Goupee 22nd International Offshore and Polar Engineering Conference – June 2012

Abstract
…a 1/50th-scale floating wind turbine atop a tension-leg platform (TLP) was designed based on Froude scaling by the University of Maine under the DeepCwind Consortium…Analysis was conducted to validate FAST for modeling the dynamics of this floating system through comparison of FAST simulation results to wave tank measurements. First, a full-scale FAST model of the as-tested scaled configuration of the system was constructed, and this model was then calibrated through comparison to the static load, free-decay, regular wave only, and wind-only tests. Part of the calibration process included modifying the airfoil properties of the wind turbine blades to more accurately characterize the aerodynamic performance achieved in the tests. The FAST model was also modified to better represent the structural response data by introducing additional platform damping and stiffness terms. Next, the calibrated FAST model was compared to the combined wind and wave tests to validate the coupled hydrodynamic and aerodynamic predictive performance. Limitations of both FAST and the data gathered from the tests are discussed in this paper.

 

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Filed under Modeling