Showing papers on "Wave power published in 2012"
TL;DR: In this article, the mean annual power absorption of a selection of eight Wave Energy Converters (WECs) with different working principles is derived based on numerical modeling. But, despite very different working principle and dimensions, power performance of the selected devices vary much less than the average power absorption.
578 citations
TL;DR: Justifying continued development and large-scale deployment of Wave Energy Converters requires quantification of the potential resource, and existing estimates do not provide insight into potential future markets, i.e. the location of the resource.
476 citations
TL;DR: In this article, a hindcast study with surface winds from the Final Global Tropospheric Analysis (FNL) provides 10 years of spectral wave data for a thorough examination of the wave resource around the world.
250 citations
TL;DR: Nearshore OWSCs are serious contenders in the mix of wave power technologies, and Aquamarine Power's 315 kW Oyster 1 prototype is described, which was deployed at the European Marine Energy Centre in August 2009.
Abstract: Oscillating wave surge converters (OWSCs) are a class of wave power technology that exploits the enhanced horizontal fluid particle movement of waves in the nearshore coastal zone with water depths of 10–20 m. OWSCs predominantly oscillate horizontally in surge as opposed to the majority of wave devices, which oscillate vertically in heave and usually are deployed in deeper water. The characteristics of the nearshore wave resource are described along with the hydrodynamics of OWSCs. The variables in the OWSC design space are discussed together with a presentation of some of their effects on capture width, frequency bandwidth response and power take-off characteristics. There are notable differences between the different OWSCs under development worldwide, and these are highlighted. The final section of the paper describes Aquamarine Power’s 315 kW Oyster 1 prototype, which was deployed at the European Marine Energy Centre in August 2009. Its place in the OWSC design space is described along with the practical experience gained. This has led to the design of Oyster 2, which was deployed in August 2011. It is concluded that nearshore OWSCs are serious contenders in the mix of wave power technologies. The nearshore wave climate has a narrower directional spread than the offshore, the largest waves are filtered out and the exploitable resource is typically only 10–20% less in 10 m depth compared with 50 m depth. Regarding the devices, a key conclusion is that OWSCs such as Oyster primarily respond in the working frequency range to the horizontal fluid acceleration; Oyster is not a drag device responding to horizontal fluid velocity. The hydrodynamics of Oyster is dominated by inertia with added inertia being a very significant contributor. It is unlikely that individual flap modules will exceed 1 MW in installed capacity owing to wave resource, hydrodynamic and economic constraints. Generating stations will be made up of line arrays of flaps with communal secondary power conversion every 5–10 units.
189 citations
TL;DR: In this paper, the authors developed a methodology that integrates both tasks seamlessly and guarantees the accurate computation of the power performance of a WEC installed at a site of interest; it involves a large dataset of deepwater records and the implementation of a high-resolution, nested spectral model, which is used to propagate 95% of the total offshore wave energy to the WEC site.
129 citations
TL;DR: In this paper, the third-generation wave model WAVEWATCH-III was used to simulate the wave field of the East China Sea and South China Sea from January 1988 to December 2009, with wind input of CCMP wind field.
Abstract: In this paper, the third-generation wave model WAVEWATCH-III (WW3) was used to simulate the wave field of the East China Sea and South China Sea from January 1988 to December 2009, with wind input of CCMP wind field. Then, the wind energy density and wave energy density were calculated by using the simulated 22-years wave-field data and CCMP data. By synthetically considering the size of energy density, the frequency of energy level and the stability of energy density, the resources of wind energy and wave energy in the East China Sea and South China Sea were analyzed and regionalized. The result can be a guide to searching location of wind & wave power plant.
115 citations
TL;DR: In this article, the authors evaluate the wave power resources around the Madeira Islands and show that the efficiency of the wave energy conversion appears to be highly dependent on the distribution of wave energy along the sea states.
106 citations
TL;DR: In this article, the effect of the wave amplitude on diffusion coefficients was investigated and it was shown that as the amplitude increases, the bounce-averaged quasi-linear diffusion coefficients become invalid.
Abstract: [1] Quasi-linear bounce-averaged diffusion coefficients for interactions between electrons and parallel propagating whistler waves in a dipole field are compared with test particle simulations. We solve equations of motion for a large number of electrons interacting with waves with a Gaussian distribution of wave power. For broadband and small amplitude waves, which are assumed by the quasi-linear analysis, our test particle simulation results agree well with quasi-linear theory predictions. We then demonstrate the effect of the wave amplitude on diffusion coefficients. We show that as the amplitude increases, the bounce-averaged quasi-linear diffusion coefficients become invalid. Critical wave amplitudes for the breakdown of the bounce-averaged diffusion coefficients for a range of energies and pitch angles are calculated for the set of wave parameters we used. Finally, we investigate the effect of wave bandwidth on bounce-averaged diffusion coefficients. Consistent with a previous theoretical prediction, bounce-averaged quasi-linear diffusion coefficients are still valid for narrowband waves, as long as the wave amplitude is small. When the amplitude of the narrowband wavefield increases, nonlinear effects such as phase-bunching and trapping become dominant and correspondingly quasi-linear theory becomes invalid. Our results demonstrate the validity of applying quasi-linear theory to interactions between electrons and small amplitude plasma waves in the radiation belt.
87 citations
TL;DR: It is finally shown that the log-Normal assumption can be seen as acceptable, even though it may be refined in the future, for the probabilistic forecasting of the wave energy flux, based on a log-normal assumption for the shape of predictive densities.
87 citations
TL;DR: In this article, the authors investigate wave power along the northern coasts of the Gulf of Oman and find that the most energetic waves are provided by the southeast Indian Ocean monsoon from June to August.
87 citations
TL;DR: In this article, the potential for energy generation was assessed based on six-hourly data from a third generation wave model (SWAN) covering the period 1995-2009, and the results were validated with buoy measurements and wave energy and power was calculated with numerical hindcast data.
TL;DR: In this article, the performance of three different types of wave energy converter (WEC) has been evaluated spatially for Australian coastal regions using Australian Renewable Energy Atlas wave energy data.
TL;DR: A decision-support tool is developed to assist siting wave energy facilities, which allows the user to balance the need for profitability of the facilities with the need to minimize conflicts with other ocean uses, and shows that the maximum combined economic benefit from wave energy and other uses is likely to be realized.
Abstract: Many hope that ocean waves will be a source for clean, safe, reliable and affordable energy, yet wave energy conversion facilities may affect marine ecosystems through a variety of mechanisms, including competition with other human uses. We developed a decision-support tool to assist siting wave energy facilities, which allows the user to balance the need for profitability of the facilities with the need to minimize conflicts with other ocean uses. Our wave energy model quantifies harvestable wave energy and evaluates the net present value (NPV) of a wave energy facility based on a capital investment analysis. The model has a flexible framework and can be easily applied to wave energy projects at local, regional, and global scales. We applied the model and compatibility analysis on the west coast of Vancouver Island, British Columbia, Canada to provide information for ongoing marine spatial planning, including potential wave energy projects. In particular, we conducted a spatial overlap analysis with a variety of existing uses and ecological characteristics, and a quantitative compatibility analysis with commercial fisheries data. We found that wave power and harvestable wave energy gradually increase offshore as wave conditions intensify. However, areas with high economic potential for wave energy facilities were closer to cable landing points because of the cost of bringing energy ashore and thus in nearshore areas that support a number of different human uses. We show that the maximum combined economic benefit from wave energy and other uses is likely to be realized if wave energy facilities are sited in areas that maximize wave energy NPV and minimize conflict with existing ocean uses. Our tools will help decision-makers explore alternative locations for wave energy facilities by mapping expected wave energy NPV and helping to identify sites that provide maximal returns yet avoid spatial competition with existing ocean uses.
TL;DR: In this article, a method for assessing the captured wave power for a device from its power capture response is presented, where a measured or calculated linear power-capture response of the device is combined with wave spectrum to compute the average captured power function.
Abstract: In developing a wave energy converter (WEC), assessing and rating the device is a difficult, but important issue. Conventionally, a large scaled device (maybe large enough for accommodating a power takeoff (PTO) system) or prototype device is needed to be tested in wave tanks or in seas in different wave conditions so that a power matrix for the device can be defined using scaling or interpolation/extrapolation methods. Alternatively, a pure numerical simulation in time-domain may be used for assessing the power capture capacities of wave energy devices. For the former, it is convincing, but can be especially difficult in the early stages of development, when small scaled models are normally used; and for the latter, the pure numerical simulation may not be very reliable and convincing, especially when the dynamic problem is very complicated. In this paper, a method for assessing the captured wave power for a device from its power capture response is presented. In the proposed method, a measured or calculated linear power capture response of the device is combined with wave spectrum to compute the average captured power function. Once the average captured power function is obtained, the overall average captured power corresponding to the wave state can be easily calculated. If a linear power capture response is obtained from a model test, the power assessment based on this proposed method can be very convincing and reliable. To illustrate the application of the proposed method, an example of a fully linear dynamic system, including the linear hydrodynamics of the floating structure and a linear power takeoff, is considered. For such a system, the frequency-domain analysis can be employed to obtain the performance of the floating device under waves and the power takeoff system. The hydrodynamic performance of the wave energy converter is then used to define the power capture response and to calculate the average captured power functions in different sea states. Then, the captured power of the device in different sea states, i.e, the power matrix, can be calculated, and accordingly, the device can be assessed and rated. To validate the proposed method, a time-domain analysis is also performed for a cross-check. In the time-domain analysis, the hydrodynamic coefficients and responses are first assessed in frequency-domain, and then transformed into the relevant terms by means of impulse response functions for establishing the time-domain (TD) equation. By comparing the results from frequency-domain and time-domain analyses of irregular waves, it can be concluded that the proposed wave energy capture assessment method can be used in assessing or rating the device.
TL;DR: The hydrodynamic principles common to many wave power converters are reviewed via two representative systems and a simple theory is given for a two-dimensional array of small buoys in well-separated rows parallel to a coast.
Abstract: The hydrodynamic principles common to many wave power converters are reviewed via two representative systems The first involves one or more floating bodies, and the second water oscillating in a fixed enclosure It is shown that the prevailing basis is impedance matching and resonance, for which the typical analysis can be illustrated for a single buoy and for an oscillating water column We then examine the mechanics of a more recent design involving a compact array of small buoys that are not resonated Its theoretical potential is compared with that of a large buoy of equal volume A simple theory is also given for a two-dimensional array of small buoys in well-separated rows parallel to a coast The effects of coastline on a land-based oscillating water column are examined analytically Possible benefits of moderate to large column sizes are explored Strategies for broadening the frequency bandwidth of high efficiency by controlling the power-takeoff system are discussed
TL;DR: In this article, the theoretical analysis of an alternative oscillating water column type wave energy converter is presented, where the problem geometry differs from earlier two dimensional studies by a modification on the front wall where the surface piercing barrier is replaced with a fully submerged barrier with a gap.
TL;DR: In this paper, the authors considered the case of a floating wave energy converter, consisting of a floater rigidly connected to a fully submerged vertical (acceleration) tube open at both ends.
TL;DR: In this paper, the authors investigated the impacts of including 500 MW of wave power into Ireland's electricity generation portfolio in the year 2020 and showed that in general the inclusion of wave energy has a negligible effect on wholesale electricity prices, reduces total system cost in Ireland and can increase CO2 emissions on the island of Ireland under certain carbon price assumptions.
TL;DR: In this article, the authors used a database of chorus power spectral density observations from the PWI Sweep Frequency Receiver (SFR) on the Polar spacecraft to generate separate distributions of wave occurrence rate and magnetic field amplitude as a function of space and geomagnetic activity.
Abstract: [1] Determining the global distribution of chorus wave power in the off-equatorial region (i.e., magnetic latitude λ > 15°) is a crucial component of understanding the contribution of chorus to radiation belt acceleration and loss. In this paper we use a database of chorus power spectral density observations from the Plasma Wave Instrument (PWI) Sweep Frequency Receiver (SFR) on the Polar spacecraft to generate separate distributions of wave occurrence rate and magnetic field amplitude as a function of space and geomagnetic activity. Previous studies focused on a band-integrated and time-averaged data product to characterize the global distribution of wave power. Using a slightly different technique, we first estimate the wave amplitude from the peak wave power spectral density for times when chorus is observed. The mean wave amplitude at a given location is then multiplied by the wave occurrence rate to yield the time-averaged amplitude. We present the spatial distributions of wave occurrence rate, mean amplitude, and time-averaged amplitude in the region of maximum statistics, λ > 15° and R = 4−8 RE. We find that waves of significant amplitude (>10 pT) can be observed in all local time sectors, but significant wave occurrence (>20%) is confined to the dawn and noon local time sectors. Wave mean and time-averaged amplitudes are also highest in the dawn and noon sectors. The spatial extent of regions with high time-averaged amplitude is primarily defined by regions of high occurrence rate. Time-averaged amplitudes exceeding ∼6 pT are observed up to a magnetic latitude of 40° at dawn and 50° at noon, while at midnight and dusk the time-averaged amplitude tends to be below that value. We also examine the geomagnetic and solar wind dependence of the spatial distribution of wave occurrence, mean amplitude, and time-averaged amplitude. In the off-equatorial region (λ > 15°), wave amplitude and occurrence on the nightside increase dramatically during disturbed geomagnetic and solar wind conditions. In contrast, waves on the dayside occur over a wider range of activity, and even during quiet conditions, mean and time-averaged amplitudes at noon significantly exceed amplitudes at midnight for disturbed times. In the dusk sector, observation of waves is mostly limited to quiet conditions, and during those times, mean amplitudes at dusk exceed those at midnight and approach amplitudes observed in the dawn sector. Parallel investigation of the independent variability of occurrence and amplitude provides a more complete picture of the chorus wave environment, particularly for application to modeling radiation belt dynamics on both short and long time scales.
TL;DR: In this paper, the authors quantitatively evaluate the wave climate variations of the northwestern Pacific and the Taiwan Waters based on long-term wave data base, and they adopted the Man-Kendall Non-Parametric Test and the Hilbert Huang EMD method to analyze the longterm wave variation trends, showing that the wave height experienced climbing trends during 1976-1985 and 1997-2006, and a descending trend during 1985-1997.
TL;DR: Some basic theory is presented that leads to predictions of distensibility and bulge wave speed in a pressurized compound rubber and fabric tube, including the effects of inelastic sectors in the circumference, longitudinal tension and the surrounding fluid.
Abstract: Laboratory measurements of the performance of the Anaconda are presented, a wave energy converter comprising a submerged water-filled distensible tube aligned with the incident waves. Experiments were carried out at a scale of around 1:25 with a 250 mm diameter and 7 m long tube, constructed of rubber and fabric, terminating in a linear power take-off of adjustable impedance. The paper presents some basic theory that leads to predictions of distensibility and bulge wave speed in a pressurized compound rubber and fabric tube, including the effects of inelastic sectors in the circumference, longitudinal tension and the surrounding fluid. Results are shown to agree closely with measurements in still water. The theory is developed further to provide a model for the propagation of bulges and power conversion in the Anaconda. In the presence of external water waves, the theory identifies three distinct internal wave components and provides theoretical estimates of power capture. For the first time, these and other predictions of the behaviour of the Anaconda, a device unlike almost all other marine systems, are shown to be in remarkably close agreement with measurements.
Journal Article•
TL;DR: In this paper, a methodology is developed for generating WEC array power time series that can be used for wave power utility integration purposes and demonstrate that significant smoothing of the total wave power output from an array can be expected.
Abstract: Ocean wave power is characterized by high power density, and wave forecasts can predict incident wave energy days in advance. These qualities make ocean wave power a promising renewable energy source. In the near future, utility-scale wave energy conversion arrays will likely be installed. However, little is currently known on the impact of large wave energy conversion (WEC) facilities on utility operation and planning. In this paper, a methodology is developed for generating WEC array power time series that can be used for wave power utility integration purposes. Sample results show that the methodology produces first-order approximations of WEC array outputs and demonstrate that significant smoothing of the total wave power output from an array can be expected.
Book•
28 Mar 2012
TL;DR: In this article, a WEC carrying a gyroscope-based energy conversion system harvests power proportionally to the square of the wave frequency, which can keep a spinning top in a quasi vertical position.
Abstract: Wave Power: how to produce clean electric energy from sea waves. Thousands of patents have been filed, hundreds of devices have been studied and tested in labs and tens of prototypes of Wave Energy Converters (WECs) have been deployed to the sea successfully harvesting wave power. The main research work has been carried out for the oceans, the most relevant source of wave energy. Closed seas, like the Mediterranean Sea, have smaller energy availability, but they have a particular feature: short waves. Short waves have higher frequency and can activate a WEC in a very effective way. For instance a WEC carrying a gyroscope-based energy conversion system harvests power proportionally to the square of the wave frequency. Gyroscopic effects can keep a spinning top in a quasi vertical position, guide airplanes, stabilize ships and, with some different architecture and strategy, harvest energy from sea waves!
TL;DR: A range of problems and theories will be introduced that will build towards a new wave energy converter (WEC) concept, with the acronym ‘ROTA’ standing for resonant over-topping absorber, and it is shown that a coupled resonant effect can be realized by inserting a water tank into a WEC, and this idea forms the basis of the ROTA device.
Abstract: In this article, a range of problems and theories will be introduced that will build towards a new wave energy converter (WEC) concept, with the acronym 'ROTA' standing for resonant over-topping absorber. First, classical results for wave power absorption for WECs constrained to operate in a single degree of freedom will be reviewed and the role of resonance in their operation highlighted. Emphasis will then be placed on how the introduction of further resonances can improve power take-off characteristics by extending the range of frequencies over which the efficiency is close to a theoretical maximum. Methods for doing this in different types of WECs will be demonstrated. Coupled resonant absorbers achieve this by connecting a WEC device equipped with its own resonance (determined from a hydrodynamic analysis) to a new system having separate mass/spring/damper characteristics. It is shown that a coupled resonant effect can be realized by inserting a water tank into a WEC, and this idea forms the basis of the ROTA device. In essence, the idea is to exploit the coupling between the natural sloshing frequencies of the water in the internal tank and the natural resonance of a submerged buoyant circular cylinder device that is tethered to the sea floor, allowing a rotary motion about its axis of attachment.
Patent•
23 Feb 2012
TL;DR: In this paper, a wave power generating system was proposed to drive a generator using the tidal motion and wave energy of the tide to produce electrical energy. But it was not shown how to transfer the motive energy of a wave to a power-transmission shaft.
Abstract: The present invention relates to a wave power generating apparatus which drives a generator using the tidal motion and wave energy of the tide to produce electrical energy. More particularly, the present invention relates to a wave power generating apparatus which generates power by transferring rotating force to a power-transmission shaft when a float moves upward by means of the upward and downward motion of a wave, and which generates power by transferring the motive energy of the float produced by the lateral force of the wave.
TL;DR: In this article, the authors used the performance characteristics of wave energy converters (WEC), resource measurements along Australia's southern coastline and global resource estimates to model projections of the future uptake of WEC globally and in Australia, and found that the majority of projected WEC installations are in the state of Victoria, which has relatively high demand and currently highly-emissions intensive sources of generation compared to states with better wave resources.
TL;DR: In this article, a model based on linear potential theory and idealized non-diffracting machines is proposed to predict wave power conversion from arbitrary arrays of oscillating water columns.
01 Jan 2012
TL;DR: In this article, the authors compared the balancing costs of a diversified system including wind and wave power productions with a system based only on wind power, and showed that when wave converters are combined balancing costs keep low, 45% lower than for wind turbines.
Abstract: There is usually a cost associated to the integration of non-fully predictable renewables in electricity markets. This cost, named balancing cost, covers the difference between the bid to the dayahead electricity market and the actual power produced. The objective of the paper is comparing the balancing costs of a diversified system including wind and wave power productions with a system based only on wind power. As a result, the paper estimates the balancing costs of wave converters, which are compared with the current balancing costs of wind turbines. The opportunities of a combined wave and wind scenario compared to the only-wind scenario are examined. The study is based on day-ahead forecasts and on real-time theoretical power productions from wave converters and wind turbines, throughout a 5month autumn and winter period, at Hanstholm, Denmark. Results show balancing costs of wave converters are 35 to 47% smaller than those brought by wind turbines. When wave converters are combined balancing costs keep low, 45% lower than for wind turbines. Finally, a diversified scenario of wind and wave technologies brings balancing costs 35 to 45% down compared to the only-wind scenario. Beyond the technical benefits of diversified scenarios, the paper identifies an economic benefit of combining wind and wave power productions.
17 Sep 2012
TL;DR: In this paper, an investigative study on developing wave energy technology in the Gulf of Mexico (GOM) is presented, where the characteristics and conditions of GOM such as weather, wave climate, and activity of the oil industry were assessed first for possible development of wave energy.
Abstract: This article presents an investigative study on developing wave energy technology in the Gulf of Mexico (GOM). The characteristics and conditions of GOM such as weather, wave climate, and activity of the oil industry were assessed first for possible development of wave energy. The linear wave theory was then reviewed to identify methods to estimate wave power. Using wave data recorded from several stations in the GOM, methods used to estimate the wave energy were verified. Based on the findings, the potential in the GOM for implementing wave energy technology was confirmed. It is expected that the wave energy captured from the GOM can provide a considerable portion of power required by operating the oil platforms in that area.