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Special Issue "Energy from the Ocean - Wave and Tidal Energy"

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A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (31 January 2013)

Special Issue Editor

Guest Editor
Prof. Dr. John Ringwood (Website)

Centre for Ocean Energy Research (COER), National University of Ireland (NUI) Maynooth, Maynooth, Co. Kildare, Ireland
Phone: +353 1 708 4766
Interests: wave and tidal energy; modeling and control of wave energy devices; energy forecasting; fault diagnostics and prognostics; techno-economic optimisation

Special Issue Information

Dear Colleagues,

While offshore wind is receiving a degree of penetration, with a number of schemes in situ or at the planning stage, wave and tidal (current) energy lags behind, due to a number of technical issues, many of which relate to operation in the marine environment. One of the main issues relates to the immaturity of the wave and tidal industries, however, with little convergence on the design of such devices and the optimal operation modes. This special issue invites papers that cover technological advances and innovations in wave and tidal energy. Topics of interest for this issue include, but are not limited to the following areas:

  • Novel device design (ideally to include some preliminary performance results)
  • Combined wave/current devices
  • Hydrodynamic and full-system modelling of wave and tidal energy systems
  • Power systems and grid compliance
  • Resource assessment, modelling and forecasting
  • Control systems and optimal operational strategies
  • Wave and tidal current energy farms – configurations, connection and mooring
  • Novel deployment, maintenance and decommissioning strategies
  • Economic evaluation and optimisation of wave and tidal energy systems
  • Environmental, legislative and social issues

Prof. Dr. John Ringwood
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs).

Published Papers (18 papers)

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Research

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Open AccessArticle Experimentally Based Model to Size the Geometry of a New OWC Device, with Reference to the Mediterranean Sea Wave Environment
Energies 2013, 6(9), 4696-4720; doi:10.3390/en6094696
Received: 5 June 2013 / Revised: 1 July 2013 / Accepted: 19 August 2013 / Published: 9 September 2013
Cited by 6 | PDF Full-text (1795 KB) | HTML Full-text | XML Full-text
Abstract
This note presents the Seabreath wave energy converter, basically a multi-chamber floating oscillating water column device, and the lumped model used to size its chambers, the ducts and the turbine. The model is based on extensive testing carried out in the wave [...] Read more.
This note presents the Seabreath wave energy converter, basically a multi-chamber floating oscillating water column device, and the lumped model used to size its chambers, the ducts and the turbine. The model is based on extensive testing carried out in the wave flume of the University of Padova using fixed and floating models with a dummy power take off and indirect measurement of the produced power. A map with the available energy in the Mediterranean Sea is also proposed, showing possible ideal application sites. The Seabreath is finally dimensioned for a quarter scale test application in the Adriatic Sea, with a 3 kW turbine, and a capacity factor of 40%. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Design of a Novel Experimental Facility for Testing of Tidal Arrays
Energies 2013, 6(8), 4117-4133; doi:10.3390/en6084117
Received: 2 May 2013 / Revised: 11 July 2013 / Accepted: 22 July 2013 / Published: 12 August 2013
Cited by 1 | PDF Full-text (1609 KB) | HTML Full-text | XML Full-text
Abstract
In order to obtain the maximum amount of energy from tidal stream extraction devices, deployment in large arrays should be studied. The area of seabed with favorable conditions is fairly limited; therefore layout spacing has to be optimized. In this paper a [...] Read more.
In order to obtain the maximum amount of energy from tidal stream extraction devices, deployment in large arrays should be studied. The area of seabed with favorable conditions is fairly limited; therefore layout spacing has to be optimized. In this paper a feasibility study for a novel experimental facility, suitable for the testing of an array of tidal devices, is presented. To avoid space and scale limitations of towing tanks, testing is proposed to be performed in large lakes or calm seas using a self-propelled vessel, which will carry an array of devices with variable spacing, creating relevant speed differences and measuring their performance and loading. Using hydrodynamic scaling laws, an appropriate size for test turbines and the range of vessel speed was determined to fulfill experimental requirements. Computational fluid dynamic simulations, using the actuator disc method, have suggested a suitable turbine array configuration to resemble real application conditions. A simplified model of the vessel was analyzed using the finite elements method to determine the main scantlings. The hull resistance calculated by empirical formulae was found to be negligible compared to the resistance of the tested turbine. It was confirmed that turbine size and speed determined by scaling laws are also reasonable from a propulsion point of view. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Comparison of the Experimental and Numerical Results of Modelling a 32-Oscillating Water Column (OWC), V-Shaped Floating Wave Energy Converter
Energies 2013, 6(8), 4045-4077; doi:10.3390/en6084045
Received: 11 March 2013 / Revised: 1 July 2013 / Accepted: 8 July 2013 / Published: 8 August 2013
Cited by 3 | PDF Full-text (12498 KB) | HTML Full-text | XML Full-text
Abstract
Combining offshore wind and wave energy converting apparatuses presents a number of potentially advantageous synergies. To facilitate the development of a proposed floating platform combining these two technologies, proof of concept scale model testing on the wave energy converting component of this [...] Read more.
Combining offshore wind and wave energy converting apparatuses presents a number of potentially advantageous synergies. To facilitate the development of a proposed floating platform combining these two technologies, proof of concept scale model testing on the wave energy converting component of this platform has been conducted. The wave energy component is based on the well-established concept of the oscillating water column. A numerical model of this component has been developed in the frequency domain, and the work presented here concerns the results of this modelling and testing. The results of both are compared to assess the validity and usefulness of the numerical model. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Discrete Displacement Hydraulic Power Take-Off System for the Wavestar Wave Energy Converter
Energies 2013, 6(8), 4001-4044; doi:10.3390/en6084001
Received: 14 May 2013 / Revised: 28 June 2013 / Accepted: 15 July 2013 / Published: 7 August 2013
Cited by 12 | PDF Full-text (5365 KB) | HTML Full-text | XML Full-text
Abstract
The Wavestar Wave Energy Converter (WEC) is a multiple absorber concept, consisting of 20 hemisphere shaped floats attached to a single platform. The heart of the Wavestar WEC is the Power Take-Off (PTO) system, converting the wave induced motion of the floats [...] Read more.
The Wavestar Wave Energy Converter (WEC) is a multiple absorber concept, consisting of 20 hemisphere shaped floats attached to a single platform. The heart of the Wavestar WEC is the Power Take-Off (PTO) system, converting the wave induced motion of the floats into a steady power output to the grid. In the present work, a PTO based on a novel discrete displacement fluid power technology is explored for the Wavestar WEC. Absorption of power from the floats is performed by hydraulic cylinders, supplying power to a common fixed pressure system with accumulators for energy smoothing. The stored pressure energy is converted into electricity at a steady pace by hydraulic motors and generators. The storage, thereby, decouples the complicated process of wave power absorption from power generation. The core for enabling this PTO technology is implementing a near loss-free force control of the energy absorbing cylinders. This is achieved by using special multi-chambered cylinders, where the different chambers may be connected to the available system pressures using fast on/off valves. Resultantly, a Discrete Displacement Cylinder (DDC) is created, allowing near loss free discrete force control. This paper presents a complete PTO system for a 20 float Wavestar based on the DDC. The WEC and PTO is rigorously modeled from incident waves to the electric output to the grid. The resulting model of +600 states is simulated in different irregular seas, showing that power conversion efficiencies above 70% from input power to electrical power is achievable for all relevant sea conditions. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
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Open AccessArticle Modeling of a Point Absorber for Energy Conversion in Italian Seas
Energies 2013, 6(6), 3033-3051; doi:10.3390/en6063033
Received: 27 March 2013 / Revised: 31 May 2013 / Accepted: 15 June 2013 / Published: 20 June 2013
Cited by 16 | PDF Full-text (689 KB) | HTML Full-text | XML Full-text
Abstract
In the present paper, we investigate the feasibility of wave electricity production in Italian seas by the deployment of the Seabased wave energy converter (WEC). A numerical model of the coupled buoy-generator system is presented, which simulates the behavior of the wave [...] Read more.
In the present paper, we investigate the feasibility of wave electricity production in Italian seas by the deployment of the Seabased wave energy converter (WEC). A numerical model of the coupled buoy-generator system is presented, which simulates the behavior of the wave energy converter under regular waves of different wave heights and periods. The hydrodynamic forces, including excitation force, radiation impedance and hydrostatic force, are calculated by linear potential wave theory, and an analytical model is used for the linear generator. Two buoys of different radii are considered to explore the effect of buoy dimension on energy conversion and device efficiency. The power output is maximized by adding a submerged object to the floating buoy, in order to bring the system into resonance with the typical wave frequencies of the sites. The simulation results show a very good agreement with the published data on the Seabased WEC. The model is used to estimate energy production at eight Italian offshore locations. The results indicate that the degree of utilization of the device is higher than 20% at the two most energetic Italian sites (Alghero and Mazara del Vallo) and that it can be considerably increased if the floating body is connected to a submerged object, thanks to the resonant behavior of the WEC. In this case, the degree of utilization of the device would be higher than 40% at most of the study sites, with the highest value at Mazara del Vallo. The work enlarges the perspective, to be confirmed by experimental tests and more accurate numerical modeling, on clean electric power production from ocean waves in the Italian seas. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Can Tidal Current Energy Provide Base Load?
Energies 2013, 6(6), 2840-2858; doi:10.3390/en6062840
Received: 11 March 2013 / Revised: 31 May 2013 / Accepted: 3 June 2013 / Published: 14 June 2013
Cited by 2 | PDF Full-text (7195 KB) | HTML Full-text | XML Full-text
Abstract
Tidal energy belongs to the class of intermittent but predictable renewable energy sources. In this paper, we consider a compact set of geographically diverse locations, which have been assessed to have significant tidal stream energy, and attempt to find the degree to [...] Read more.
Tidal energy belongs to the class of intermittent but predictable renewable energy sources. In this paper, we consider a compact set of geographically diverse locations, which have been assessed to have significant tidal stream energy, and attempt to find the degree to which the resource in each location should be exploited so that the aggregate power from all locations has a low variance. An important characteristic of the locations chosen is that there is a good spread in the peak tidal flow times, though the geographical spread is relatively small. We assume that the locations, all on the island of Ireland, can be connected together and also assume a modular set of tidal turbines. We employ multi-objective optimisation to simultaneously minimise variance, maximise mean power and maximise minimum power. A Pareto front of optimal solutions in the form of a set of coefficients determining the degree of tidal energy penetration in each location is generated using a genetic algorithm. While for the example chosen the total mean power generated is not great (circa 100 MW), the case study demonstrated a methodology that can be applied to other location sets that exhibit similar delays between peak tidal flow times. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Characteristics of the Operational Noise from Full Scale Wave Energy Converters in the Lysekil Project: Estimation of Potential Environmental Impacts
Energies 2013, 6(5), 2562-2582; doi:10.3390/en6052562
Received: 5 February 2013 / Revised: 10 May 2013 / Accepted: 14 May 2013 / Published: 21 May 2013
Cited by 4 | PDF Full-text (1716 KB) | HTML Full-text | XML Full-text
Abstract
Wave energy conversion is a clean electric power production technology. During operation there are no emissions in the form of harmful gases. However there are unsolved issues considering environmental impacts such as: electromagnetism; the artificial reef effect and underwater noise. Anthropogenic noise [...] Read more.
Wave energy conversion is a clean electric power production technology. During operation there are no emissions in the form of harmful gases. However there are unsolved issues considering environmental impacts such as: electromagnetism; the artificial reef effect and underwater noise. Anthropogenic noise is increasing in the oceans worldwide and wave power will contribute to this sound pollution in the oceans; but to what extent? The main purpose of this study was to examine the noise emitted by a full scale operating Wave Energy Converter (WEC) in the Lysekil project at Uppsala University in Sweden. A minor review of the hearing capabilities of fish and marine mammals is presented to aid in the conclusions of impact from anthropogenic sound. A hydrophone was deployed to the seabed in the Lysekil research site park at distance of 20 and 40 m away from two operational WECs. The measurements were performed in the spring of 2011. The results showed that the main noise was a transient noise with most of its energy in frequencies below 1 kHz. These results indicate that several marine organisms (fish and mammals) will be able to hear the operating WECs of a distance of at least 20 m. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Stochastic Rating of Storage Systems in Isolated Networks with Increasing Wave Energy Penetration
Energies 2013, 6(5), 2481-2500; doi:10.3390/en6052481
Received: 27 March 2013 / Revised: 24 April 2013 / Accepted: 25 April 2013 / Published: 15 May 2013
Cited by 7 | PDF Full-text (1012 KB) | HTML Full-text | XML Full-text
Abstract
The future success of wave energy in the renewable energy mix depends on the technical advancements of the specific components and systems, on the grid access availability and, ultimately, on the economical profitability of the investment. Small and remote islands represent an [...] Read more.
The future success of wave energy in the renewable energy mix depends on the technical advancements of the specific components and systems, on the grid access availability and, ultimately, on the economical profitability of the investment. Small and remote islands represent an ideal framework for wave energy exploitation, due both to resource availability and to the current high cost of electricity that mostly relies on diesel generation. Energy storage can be the enabling technology to match the intermittent power generation from waves to the energy needs of the local community. In this paper real data from La Palma, in the Canary Islands, are used as a basis for the considered test case. As a first step the study quantifies the expected power production from Wave Energy Converter (WEC) arrays, based on data from the Lifesaver point absorber developed by Fred. Olsen. Then, a stochastic optimization approach is applied to evaluate the convenience of energy storage introduction for reducing the final cost of energy and to define the corresponding optimal rating of the storage devices. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Modeling Evaluation of Tidal Stream Energy and the Impacts of Energy Extraction on Hydrodynamics in the Taiwan Strait
Energies 2013, 6(4), 2191-2203; doi:10.3390/en6042191
Received: 7 February 2013 / Revised: 13 April 2013 / Accepted: 14 April 2013 / Published: 18 April 2013
Cited by 4 | PDF Full-text (1535 KB) | HTML Full-text | XML Full-text
Abstract
Tidal stream speeds in straits are accelerated because of geographic and bathymetric features. For instance, narrow channels and shallows can cause high tidal stream energy. In this study, water level and tidal current were simulated using a three-dimensional semi-implicit Eulerian-Lagrangian finite-element model [...] Read more.
Tidal stream speeds in straits are accelerated because of geographic and bathymetric features. For instance, narrow channels and shallows can cause high tidal stream energy. In this study, water level and tidal current were simulated using a three-dimensional semi-implicit Eulerian-Lagrangian finite-element model to investigate the complex tidal characteristics in the Taiwan Strait and to determine potential locations for harnessing tidal stream energy. The model was driven by nine tidal components (M2, S2, N2, K2, K1, O1, P1, Q1, and M4) at open boundaries. The modeling results were validated with the measured data, including water level and tidal current. Through the model simulations, we found that the highest tidal currents occurred at the Penghu Channel in the Taiwan Strait. The Penghu Channel is an appropriate location for the deployment of a tidal turbine array because of its deep and flat bathymetry. The impacts of energy extraction on hydrodynamics were assessed by considering the momentum sink approach. The simulated results indicate that only minimal impacts would occur on water level and tidal current in the Taiwan Strait if a turbine array (55 turbines) was installed in the Penghu Channel. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Evaluation of a Model for Predicting the Tidal Velocity in Fjord Entrances
Energies 2013, 6(4), 2031-2051; doi:10.3390/en6042031
Received: 29 January 2013 / Revised: 29 March 2013 / Accepted: 30 March 2013 / Published: 9 April 2013
Cited by 2 | PDF Full-text (2691 KB) | HTML Full-text | XML Full-text
Abstract
Sufficiently accurate and low-cost estimation of tidal velocities is of importance when evaluating a potential site for a tidal energy farm. Here we suggest and evaluate a model to calculate the tidal velocity in fjord entrances. The model is compared with tidal [...] Read more.
Sufficiently accurate and low-cost estimation of tidal velocities is of importance when evaluating a potential site for a tidal energy farm. Here we suggest and evaluate a model to calculate the tidal velocity in fjord entrances. The model is compared with tidal velocities from Acoustic Doppler Current Profiler (ADCP) measurements in the tidal channel Skarpsundet in Norway. The calculated velocity value from the model corresponded well with the measured cross-sectional average velocity, but was shown to underestimate the velocity in the centre of the channel. The effect of this was quantified by calculating the kinetic energy of the flow for a 14-day period. A numerical simulation using TELEMAC-2D was performed and validated with ADCP measurements. Velocity data from the simulation was used as input for calculating the kinetic energy at various locations in the channel. It was concluded that the model presented here is not accurate enough for assessing the tidal energy resource. However, the simplicity of the model was considered promising in the use of finding sites where further analyses can be made. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Optimal Constant DC Link Voltage Operation of a Wave Energy Converter
Energies 2013, 6(4), 1993-2006; doi:10.3390/en6041993
Received: 6 February 2013 / Revised: 21 March 2013 / Accepted: 22 March 2013 / Published: 8 April 2013
Cited by 8 | PDF Full-text (3537 KB) | HTML Full-text | XML Full-text
Abstract
This article proposes a simple and reliable damping strategy for wave powerfarm operation of small-scale point-absorber converters. The strategy is based on passiverectification onto a constant DC-link, making it very suitable for grid integration of the farm.A complete model of the system [...] Read more.
This article proposes a simple and reliable damping strategy for wave powerfarm operation of small-scale point-absorber converters. The strategy is based on passiverectification onto a constant DC-link, making it very suitable for grid integration of the farm.A complete model of the system has been developed in Matlab Simulink, and uses real sitedata as input. The optimal constant DC-voltage is evaluated as a function of the significantwave height and energy period of the waves. The total energy output of the WEC is derivedfor one year of experimental site data. The energy output is compared for two cases, onewhere the optimal DC-voltage is determined and held constant at half-hour basis throughoutthe year, and one where a selected value of the DC-voltage is kept constant throughout theyear regardless of sea state. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
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Open AccessArticle Experimental Update of the Overtopping Model Used for the Wave Dragon Wave Energy Converter
Energies 2013, 6(4), 1961-1992; doi:10.3390/en6041961
Received: 5 February 2013 / Revised: 15 March 2013 / Accepted: 26 March 2013 / Published: 3 April 2013
Cited by 3 | PDF Full-text (2255 KB) | HTML Full-text | XML Full-text
Abstract
An overtopping model specifically suited for Wave Dragon is needed in order to improve the reliability of its performance estimates. The model shall be comprehensive of all relevant physical processes that affect overtopping and flexible to adapt to any local conditions and [...] Read more.
An overtopping model specifically suited for Wave Dragon is needed in order to improve the reliability of its performance estimates. The model shall be comprehensive of all relevant physical processes that affect overtopping and flexible to adapt to any local conditions and device configuration. An experimental investigation is carried out to update an existing formulation suited for 2D draft-limited, low-crested structures, in order to include the effects on the overtopping flow of the wave steepness, the 3D geometry of Wave Dragon, the wing reflectors, the device motions and the non-rigid connection between platform and reflectors. The study is carried out in four phases, each of them specifically targeted at quantifying one of these effects through a sensitivity analysis and at modeling it through custom-made parameters. These are depending on features of the wave or the device configuration, all of which can be measured in real-time. Instead of using new fitting coefficients, this approach allows a broader applicability of the model beyond the Wave Dragon case, to any overtopping WEC or structure within the range of tested conditions. Predictions reliability of overtopping over Wave Dragon increased, as the updated model allows improved accuracy and precision respect to the former version. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Experimental Study Related to the Mooring Design for the 1.5 MW Wave Dragon WEC Demonstrator at DanWEC
Energies 2013, 6(4), 1863-1886; doi:10.3390/en6041863
Received: 28 January 2013 / Revised: 22 March 2013 / Accepted: 25 March 2013 / Published: 2 April 2013
Cited by 3 | PDF Full-text (627 KB) | HTML Full-text | XML Full-text
Abstract
The paper presents the results of an experimental study identifying the response of a 1.5 MW Wave Dragon to extreme conditions typical of the DanWEC test center. The best strategies allowing for a reduction in the extreme mooring tension have also been [...] Read more.
The paper presents the results of an experimental study identifying the response of a 1.5 MW Wave Dragon to extreme conditions typical of the DanWEC test center. The best strategies allowing for a reduction in the extreme mooring tension have also been investigated, showing that this is possible by increasing the surge natural period of the system. The most efficient strategy in doing this is to provide the mooring system with a large horizontal compliance (typically in the order of 100 s), which shall be therefore assumed as design configuration. If this is not possible, it can also be partly achieved by lowering the floating level to a minimum (survivability mode) and by adopting a negative trim position. The adoption of the design configuration would determine in a 100-year storm extreme mooring tensions in the order of 0.9 MN, 65% lower than the worst case experienced in the worst case configuration. At the same time it would lead to a reduction in the extreme motion response, resulting in heave and pitch oscillation heights of 7 m and 19° and surge excursion of 12 m. Future work will numerically identify mooring configurations that could provide the desired compliance. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Evaluation of Various Technologies for Wave Energy Conversion in the Portuguese Nearshore
Energies 2013, 6(3), 1344-1364; doi:10.3390/en6031344
Received: 7 December 2012 / Revised: 6 February 2013 / Accepted: 18 February 2013 / Published: 5 March 2013
Cited by 40 | PDF Full-text (1127 KB) | HTML Full-text | XML Full-text
Abstract
The objective of the present work is to perform an evaluation of the performance provided by various technologies for wave energy conversion in the Portuguese continental coastal environment. The wave climate in the target area is first analyzed using the results from [...] Read more.
The objective of the present work is to perform an evaluation of the performance provided by various technologies for wave energy conversion in the Portuguese continental coastal environment. The wave climate in the target area is first analyzed using the results from three years of simulations with a wave prediction system based on numerical models. Based on the above data, diagrams for the bivariate distributions of the sea states occurrences, defined by the significant wave height and the energy period, are designed for both winters and whole years. On this basis, the output of five different technologies for the conversion of wave energy is assessed in some relevant locations from the Portuguese nearshore. According to the results obtained, the Portuguese continental coastal environment appears to be appropriate for the wave energy extraction. At the same time, the present work shows that the output of the wave energy conversion devices does not depend only on the average wave energy but is also dependent on the distribution of the wave energy among the sea states of different periods. For this reason, a good agreement between the characteristics of the power matrices of the wave energy converters operating in a certain place and the diagrams for the bivariate distributions of the sea states occurrences corresponding to the considered location represents a key issue in selecting the most appropriate technology for wave energy conversion. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
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Open AccessArticle Tidal Current Energy Resources off the South and West Coasts of Korea: Preliminary Observation-Derived Estimates
Energies 2013, 6(2), 566-578; doi:10.3390/en6020566
Received: 20 November 2012 / Revised: 4 January 2013 / Accepted: 17 January 2013 / Published: 24 January 2013
Cited by 4 | PDF Full-text (1202 KB) | HTML Full-text | XML Full-text
Abstract
In this study we estimate the prospective tidal current energy resources off the south and west coasts of Korea and explore the influence of modeling tidal current energies based on 15-day versus month-long data records for regimes with pronounced perigean/apogean influences. The [...] Read more.
In this study we estimate the prospective tidal current energy resources off the south and west coasts of Korea and explore the influence of modeling tidal current energies based on 15-day versus month-long data records for regimes with pronounced perigean/apogean influences. The tidal current energy resources off southern and western Korea were calculated using 29-day in situ observation data from 264 stations. The resultant annual energy densities found at each station were categorized into six groups, with a greater percentage of sites falling into the lower-energy groups: 1.1% for >10 MWh·m−2; 2.7% for 5 to 10 MWh·m−2; 6.8% for 3 to 5 MWh·m−2; 9.1% for 2 to 3 MWh·m−2 and 80.3% for <2 MWh·m−2. Analysis shows that the greatest concentration of high annual energy densities occurs in the Jeonnam Province coastal region on the western tip of southwest Korea: 23 MWh·m−2 at Uldolmok, 15 MWh·m−2 at Maenggol Sudo, 9.2 MWh·m−2 at Geocha Sudo and 8.8 MWh·m−2 at Jaingjuk Sudo. The second highest annual energy density concentration, with 16 MWh·m−2, was found in Gyudong Suro, in Gyeonggi Province’s Gyeonggi Bay. We then used data from the 264 stations to examine the effect of perigean and apogean influences on tidal current energy density evaluations. Compared to derivations using month-long records, mean annual energy densities derived using 15-day perigean spring-neap current records alone overestimate the annual mean energy by around 10% whereas those derived using only the apogean records underestimate energy by around 12%. In particular, accuracy of the S2 contribution to the energy density calculations is significantly affected by use of the 15-day data sets, compared to the M2 component, which is relatively consistent. Further, annual energy density estimates derived from 29-day records but excluding the N2 constituent underestimate the potential resource by about 5.4%. Results indicate that one month of data is required to accurately estimate tidal current energy in regimes showing pronounced perigean and apogean differences in spring-neap tidal current patterns and that inclusion of the N2 constituent in calculations is preferable. This finding has widespread applicability for green energy resource assessments, for example, in regions of the Unites States Atlantic coast and in New Zealand. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessArticle Non Breaking Wave Forces at the Front Face of Seawave Slotcone Generators
Energies 2012, 5(11), 4779-4803; doi:10.3390/en5114779
Received: 17 September 2012 / Revised: 1 November 2012 / Accepted: 16 November 2012 / Published: 19 November 2012
Cited by 15 | PDF Full-text (1351 KB) | HTML Full-text | XML Full-text
Abstract
The Seawave Slotcone Generator (WAVEnergy SAS, 2003) is a wave energy converter based on the overtopping principle. Although it has been effectively researched during the last decade, no design tool has been supplied to estimate the hydrodynamic loads the waves exert on [...] Read more.
The Seawave Slotcone Generator (WAVEnergy SAS, 2003) is a wave energy converter based on the overtopping principle. Although it has been effectively researched during the last decade, no design tool has been supplied to estimate the hydrodynamic loads the waves exert on its front face. In this article a set of well reliable 3D experiments has been re-analyzed, in order to get indications on possible calculation methods. It is shown that the Japanese design tools for monolithic sea dikes may be reasonably adapted to the present case. Finally a new approach is presented, which is based on the so called momentum flux principle; the resulting predictive equation fits the experimental data remarkably well. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)

Review

Jump to: Research

Open AccessReview A Political, Economic, Social, Technology, Legal and Environmental (PESTLE) Approach for Risk Identification of the Tidal Industry in the United Kingdom
Energies 2013, 6(10), 5023-5045; doi:10.3390/en6105023
Received: 8 July 2013 / Revised: 14 August 2013 / Accepted: 4 September 2013 / Published: 27 September 2013
Cited by 6 | PDF Full-text (239 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a comprehensive analysis of renewable and especially tidal energy through a political, economic, social, technology, legal and environmental (PESTLE) analysis approach and by reviewing the most up to date relevant literature. The study focuses on the United Kingdom given [...] Read more.
This paper presents a comprehensive analysis of renewable and especially tidal energy through a political, economic, social, technology, legal and environmental (PESTLE) analysis approach and by reviewing the most up to date relevant literature. The study focuses on the United Kingdom given the favourable environmental resources for such technologies; the number of different design concepts that are currently under development as well as the research funding that has been invested over the last few years. Findings of the analysis identify the risks and multiple stakeholders involved at all stages of the tidal energy projects development from the conceptualization of the design, right through to decommissioning. Many of the stakeholders present benefits to the tidal developers through funding, incentives and knowledge sharing, but at the same time they also present potential risks to the future of projects. This is mostly down to different approaches of the most important aspect of tidal energy that needs to be considered, making it hard for technologists and developers to equally address all requirements. From this research it can be concluded that several of these risks can be mitigated early on providing that particular stakeholders are involved at the correct stage of a project. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)
Open AccessReview 2002–2012: 10 Years of Research Progress in Horizontal-Axis Marine Current Turbines
Energies 2013, 6(3), 1497-1526; doi:10.3390/en6031497
Received: 30 November 2012 / Revised: 13 February 2013 / Accepted: 26 February 2013 / Published: 6 March 2013
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Abstract
Research in marine current energy, including tidal and ocean currents, has undergone significant growth in the past decade. The horizontal-axis marine current turbine is one of the machines used to harness marine current energy, which appears to be the most technologically and [...] Read more.
Research in marine current energy, including tidal and ocean currents, has undergone significant growth in the past decade. The horizontal-axis marine current turbine is one of the machines used to harness marine current energy, which appears to be the most technologically and economically viable one at this stage. A number of large-scale marine current turbines rated at more than 1 MW have been deployed around the World. Parallel to the development of industry, academic research on horizontal-axis marine current turbines has also shown positive growth. This paper reviews previous research on horizontal-axis marine current turbines and provides a concise overview for future researchers who might be interested in horizontal-axis marine current turbines. The review covers several main aspects, such as: energy assessment, turbine design, wakes, generators, novel modifications and environmental impact. Future trends for research on horizontal-axis marine current turbines are also discussed. Full article
(This article belongs to the Special Issue Energy from the Ocean - Wave and Tidal Energy)

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