Showing papers on "Wave power published in 2006"

Plasma generation using high-power millimeter-wave beam and its application for thrust generation

Abstract: Propagation of an ionization front in the beam channel was observed after plasma was generated using a 170GHz millimeter-wave beam in the atmosphere. The propagation velocity of the ionization front was found to be supersonic when the millimeter-wave power density was greater than 75kWcm−2. The momentum coupling coefficient Cm, a ratio of the propulsive impulse to the input energy, was measured using conical and cylindrical thruster models. A Cm value greater than 350NMW−1 was recorded when the ionization front propagated with supersonic velocity.

Numerical and experimental modelling of a modified version of the Edinburgh Duck wave energy device

Abstract: This paper presents recent numerical studies conducted at The University of Edinburgh related to a modified version of the Edinburgh duck wave energy converter. Its purpose is seawater desalination rather than electricity production, but under the assumptions taken the results can be applied to both versions. From the design point of view, the key innovation is the change of the shape of the device. Wave energy can be converted into useful work by the same pitching motion by means of a circular cylinder with an offset axis of rotation without the front beak, allowing significant cost reduction. The results to be presented were obtained using the Boundary Element Method (BEM) package WAMIT, based on linear wave theory. The hydrodynamic behaviour of the device is assessed, allowing comparisons with experimental work on a 1:33 scale model. Full-scale figures are also presented. The influences of both the position of the axis of rotation and the submergence ratio are evaluated. A total of ten different config...

Wave power generator

Abstract: A machine and a process to produce compressed air by sea waves, using the weight of the floating platform with its fixture using its up and down movement to compress air in both directions to absorb the maximum energy of that wave in a direct drive bidirectional pump with a single piston wherein the kinetic energy and wave bouncy force is used to compress ambient air as stored energy. This unique arrangement doubles air volume for compression in both directions in any single wave curve, doubles the energy production in both upper and lower chambers of the pump and multiplies the “psi” based on the float thrust area against the size of the piston in the pump. The preferred embodiment can be used as a stand alone unit as well as in array formation for the desired output 24/7.

Wave Energy Conversion Linear Synchronous Permanent Magnet Generator

Abstract: This thesis studies the electric aspects of a linear synchronous permanent magnet generator. The generator is designed for use in a wave energy converter, which determines the fundamental requireme ...

Remarks on nonlinear relation among phases and frequencies in modulational instabilities of parallel propagating Alfvén waves

Abstract: . Nonlinear relations among frequencies and phases in modulational instability of circularly polarized Alfven waves are discussed, within the context of one dimensional, dissipation-less, unforced fluid system. We show that generation of phase coherence is a natural consequence of the modulational instability of Alfven waves. Furthermore, we quantitatively evaluate intensity of wave-wave interaction by using bi-coherence, and also by computing energy flow among wave modes, and demonstrate that the energy flow is directly related to the phase coherence generation. We first discuss the modulational instability within the derivative nonlinear Schrodinger (DNLS) equation, which is a subset of the Hall-MHD system including the right- and left-hand polarized, nearly degenerate quasi-parallel Alfven waves. The dominant nonlinear process within this model is the four wave interaction, in which a quartet of waves in resonance can exchange energy. By numerically time integrating the DNLS equation with periodic boundary conditions, and by evaluating relative phase among the quartet of waves, we show that the phase coherence is generated when the waves exchange energy among the quartet of waves. As a result, coherent structures (solitons) appear in the real space, while in the phase space of the wave frequency and the wave number, the wave power is seen to be distributed around a straight line. The slope of the line corresponds to the propagation speed of the coherent structures. Numerical time integration of the Hall-MHD system with periodic boundary conditions reveals that, wave power of transverse modes and that of longitudinal modes are aligned with a single straight line in the dispersion relation phase space, suggesting that efficient exchange of energy among transverse and longitudinal wave modes is realized in the Hall-MHD. Generation of the longitudinal wave modes violates the assumptions employed in deriving the DNLS such as the quasi-static approximation, and thus long time evolution of the Alfven modulational instability in the DNLS and in the Hall-MHD models differs significantly, even though the initial plasma and parent wave parameters are chosen in such a way that the modulational instability is the most dominant instability among various parametric instabilities. One of the most important features which only appears in the Hall-MHD model is the generation of sound waves driven by ponderomotive density fluctuations. We discuss relationship between the dispersion relation, energy exchange among wave modes, and coherence of phases in the waveforms in the real space. Some relevant future issues are discussed as well.

Prospects for Ocean Energy in Malaysia

Abstract: The ocean one of the most perpetual sources of energy and has already been exploited on a small scale. Some technologies are being developed to exploit the large potential of this energy source. This paper will focus on ocean energy as an alternative source in Malaysia. The current development of various devices to extract the ocean energy will be reviewed. Although technologies are currently being developed in the areas of tidal power, wave power, thermal energy gradient, current energy, winds and salinity gradient, not all of these are suitable for Malaysian sea areas. This paper surveys the available Malaysian oceanographic data and identifies the potential sources of energy.

Optimizing the Power Take Off of a Wave Energy Converter With Regard to the Wave Climate

Abstract: Considered as a source of renewable energy, wave is a resource featuring high variability at all time scales. Furthermore wave climate also changes significantly from place to place. Wave energy converters are very often tuned to suit the more frequent significant wave period at the project site. In this paper we show that optimizing the device necessitates accounting for all possible wave conditions weighted by their annual occurrence frequency, as generally given by the classical wave climate scatter diagrams. A generic and very simple wave energy converter is considered here. It is shown how the optimal parameters can be different considering whether all wave conditions are accounted for or not, whether the device is controlled or not, whether the productive motion is limited or not. We also show how they depend on the area where the device is to be deployed, by applying the same method to three sites with very different wave climate.

Wave period group statistics for real sea waves and wave energy extraction

Abstract: The paper describes the analyses of wave data recorded at various locations and water depths around northern Europe to determine the temporal characteristics of individual wave periods and other wave period statistics. These analyses show that, just as there are group characteristics for wave heights, there are similar, but less pronounced, characteristics for wave periods. This is observed in three separate sets of data from different locations in water depths of 18, 50, and 130 m. It is also found in time series simulated using random linear wave theory from a Jonswap spectrum. A simple, new statistic, R, is introduced that measures the rate of change in the wave period from one wave to the next. This is relevant to wave energy devices that may try to tune themselves to obtain optimum power output from each individual wave. The characteristics of this statistic and its variation with significant wave height, mean energy period, and spectral bandwidth have been examined for the three datasets and are dis...

Inventory of Canada’s Offshore Wave Energy Resources

Abstract: Global warming, the depletion of conventional energy reserves and the rising cost of electricity generation have sparked renewed interest in renewable wave energy within Canada and internationally. Significant advances in wave energy converters have been made in recent years, and there is a growing realization in many countries, particularly those in Europe, that these technologies will be ready for large scale deployments within the next five to ten years (ABP, 2004). Despite these recent developments, very little effort has been directed to quantifying and mapping wave energy resources in Canada in the past. This paper presents results from a recent study in which the wave energy resource in Canada’s Pacific and Atlantic waters is quantified by analysing a large quantity of data obtained from four sources: direct wave measurements; two wind-wave hindcasts of the North Atlantic; and a single hindcast of the Northeast Pacific. Each data source is described and the methods used to analyse the data sets are explained in detail. The derived wave power estimates, including their seasonal and spatial variability, are presented and discussed. Results obtained from the direct measurements and the wind-wave hindcasts are also compared. The paper also includes a review of the theoretical background required to estimate wave energy. The waters off Canada’s Pacific and Atlantic coasts are endowed with rich wave energy resources. The results presented here define the scale of these resources, as well as their significant spatial and seasonal variations.Copyright © 2006 by National Research Council of Canada

Wave power energy converter

Abstract: PROBLEM TO BE SOLVED: To provide a wave power energy converter improving the safety and life of the converter by leveling the variation of the energy conversion rate of a surface wave in one cycle and wire tension to suppress the maximal values thereof. SOLUTION: An energy storage means is composed of a tension pulley 9 and a support spring 10. A float 4 floating on the surface of water is vertically moved by the variation of water level by wave. When the float 4 is largely lowered by a strong surface wave of water, the tension f f is increased. When the tension f f is increased, the tension pulley 9 installed between a drive pulley 6 and a fixed pulley 7 is retracted downward against the force of the support spring 10 to store energy based on the tension f t . The energy is released when the surface of water is raised where effective wire tension is set at a negative value, converted into the energy of rotating motion, discharged and supplied to a generator 1 for power generation. COPYRIGHT: (C)2008,JPO&INPIT

Wave Spectral Bandwidth as a Measure of Available Wave Power

Abstract: A key requirement in the description of the performance of a wave energy converter is how the efficiency of power capture changes with the properties of the sea. This paper examines the effect of two generic power transfer functions (PTF) on power production from six simulated wave spectra. These were chosen to represent a series of wind, wind-swell mixed and swell dominated seas. The spread in energy within the sea state as defined by a variety of bandwidth parameters was examined to determine if there was a correlation between the width of the transfer function and the sea bandwidth. It was found that, for the ‘constant’ height PTF, the bandwidth parameter Bb (calculated using zeroth, minus-one and minus-two spectral moments) provided the best correlation. Customary bandwidths e and ν performed poorly. When the PTF was allowed to vary in height as well as width there was little improvement in correlation from the un-scaled results.Copyright © 2006 by ASME

Wave power plant for electricity generation has float movable up and down to create torque in rotating rod

Abstract: The wave power plant is arranged on the sea surface. It has a frame with a central horizontal rotating rod (4) and floats (10) on either side of it. Rotating arms (5, 6, 7, 8, 9) connect the floats to the rotating rod. When the wave causes the float to move up, it creates torque in the rotating rod in the direction of the rod's rotation. When the float is moved down, the same occurs.

Numerical Analysis on Wave Energy Absorption of OWC-type Wave Power Generation

Abstract: A numerical analysis is made to investigate the wave absorption efficiency of a OWC-type wave power generator. Energy absorption by an OWC(Oscillating Water Column) air-chamber is computed in regular waves, taking account of the oscillating surface-pressure, due to pressure drop, across the duct of the air chamber. The problem is formulated in the scope of potential theory and solved by the Localized Finite Element Method(LFEM), based on the classical variational principle. The efficiency of energy absorption is investigated by. changing wave conditions, sea-bottom slope and pressure drop coefficient.

Parameter variation and part-load efficiencies of wave energy conversion

Abstract: There are growing provisions to include ocean wave energy as an alternate renewable energy source. There are also several challenges that need to be addressed before the technology gains full engineering and market confidence. One of the main technical hurdles is the need to address part-load problems of wave energy converters resulting from bathymetric conditions and variations in wave parameters such as wave frequency and height. As such, the wave phenomenon is inherently variable in time and space. This is compounded by the fact that wave energy conversion devices are less efficient at part load. This paper discusses sources of part loads in wave energy conversion including their impact on system efficiency for a California weather scenario, also relating wave energy conversion techniques to part-load efficiencies.

Cross-Shore Internal Waves in Zanpa Coastal Region of Okinawa Island

Abstract: Comprehensive field observations were made to establish a baseline of the existing tidal current structure and internal wave phenomena in a coastal region. Water temperature distributions at different depths and vertical profiles of horizontal current were examined in detail. Time series of horizontal current and near-bottom temperature fluctuations are explained by internal wave theories following two-layer and continuous density distributions. Study results show the propagation of cross-shore internal waves in an area where bottom topography is characterized by near-critical slope. Near-bottom cold internal current that flowed toward the shore significantly influenced the water temperature distributions in the region. The vertical structure of east-west horizontal current showed that its transmission was consistent with the phase propagation of theoretically calculated internal waves.

A Generic Method for Determining WEC Power Conversion from a Random Sea

Abstract: This paper examines the calculation of the power delivered from a wave energy converter using a conventional frequency transfer function approach and compares this with an alternative analysis based on a “wave-by-wave” basis. This alternative method goes some way to estimating the power that a resonant device, capable of tuning, might extract from a random sea state. For the purposes of this paper the time series were synthesized from a range of spectra representative of unimodal and bimodal sea states. The calculated power from each method is compared. An initial examination of how the delivered power can be related to the bandwidth of the sea is also presented.

Reception apparatus and adaptive algorithm control method

Abstract: PROBLEM TO BE SOLVED: To use both a desired wave optimized adaptive algorithm and a spatial component suppressed adaptive algorithm while compensating for defects thereof. SOLUTION: A reception apparatus 1a with an array antenna includes: an MMSE control unit 17 for adaptively controlling reception waves arriving at antenna elements 10 using the desired wave optimized adaptive algorithm for optimizing the reception of a desired wave while utilizing a known signal; a desired wave power information acquisition unit 18 for acquiring desired wave power information indicating the power level of the desired wave from the reception waves; an unwanted wave power information acquisition unit 19 for acquiring unwanted wave power information indicating the power level of an unwanted wave included in the reception waves; and a use adaptive algorithm change unit 14 for changing, in accordance with the unwanted wave power information and the desired wave power information, the adaptive algorithm to be used for an adaptive control section 2a into the spatial component suppressed adaptive algorithm for suppressing spatial components constituting the reception waves in accordance with the power. COPYRIGHT: (C)2008,JPO&INPIT

Receiver and desired wave versus interference power ratio measurement method

Abstract: PROBLEM TO BE SOLVED: To calculate a desired wave versus interference power ratio by using a power value of a received signal for every antenna and to correctly discriminatte synchronization when communication can be established through proper phase control even in an initial state wherein the antennas at a transmitter side are not correctly controlled. SOLUTION: A demodulation section 200 demodulates symbols transmitted from two antennas to provide outputs of two demodulated symbols, square sections 321a, 321b respectively square the two demodulated symbols to calculate two power values, an adder section 322 summates the two power values to calculate a desired wave power, an ISCP calculation section 330 calculates an interference power from the two demodulated symbols, and a SIR calculation section 340 subtracts the interference wave power from the desired power to calculate the desired wave versus interference wave power ratio. COPYRIGHT: (C)2006,JPO&NCIPI

진동수주형 파력발전기의 에너지 흡수효율 해석

Abstract: A numerical analysis is made to investigate the wave absorption efficiency of a OWC-type wave power generator. Energy absorption by an OWC(Oscillating Water Column) air-chamber is computed in regular waves, taking account of the oscillating surface-pressure, due to pressure drop, across the duct of the air chamber. The problem is formulated in the scope of potential theory and solved by the Localized Finite Element Method(LFEM), based on the classical variational principle. The efficiency of energy absorption is investigated by changing wave conditions, sea-bottom slope and pressure drop coefficient.

Three phase AC sine wave electronic voltage regulator

Abstract: Present invention relates to a voltage regulator, especially a three phase alternating current sine wave electronic voltage controller It contains chopped wave, power switch k 1, k 2, flow current power switch 3, high frequency wave generation driving circuit PWM, chopped wave power switch k input end connected with power supply, output end connected with one input end of flow current power switch k 3, control end of chopped wave power k 1 connected with one output end of high frequency wave generation driving circuit PWM, input end of chopped wave power switch connected with power supply, output end connected with another input end of flow current power switch k 3, control end of chopped wave power switch k 2 connected with another output end of high frequency wave generation driving circuit PWM, the third input end of flow current power switch k connected with power supply, third control end connected with output end of high frequency wave generation driving circuit PWM Said invention has low cost and small volume advantage