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A series of quantitative analyses were performed to identify the wave properties and potential, by means of records collected from an offshore buoy in North-West Ireland. Based on the data collected, a series of quantitative analyses was conducted to determine the dominant wind directions and wave properties on an annual basis. In addition, the wave power is computed based on relevant wave heights and periods, and the Pierson-Moskowitz spectral model was used to generate the maximum wave energy spectra for each year. The results show that waves with wave powers of around 100 kW/m were mostly approaching eastward at a rather narrow frequency. In order to compare the relative capture width and the power absorption capacity of three floating structures, the Wave Dragon, Board Net Breakwater, and Cylindrical Floating Breakwater are analyzed. Also outlined is the impact of the transmission coefficient on the effectiveness of wave energy converters (WEC) throughout the energy harvesting process. This was accomplished by fusing information from three distinct field investigations and experimental research with four different wave transmission coefficient models. The results show that as the wave steepness increases, the transmission coefficient decreases and the hydrodynamic performance of wave energy converters increases. Also, it is found that the hydrodynamic efficiency of wave energy converters is higher in summer than in winter, and the Wave Dragon is the most efficient wave energy converter in regard to relative capture width and power absorption. [ABSTRACT FROM AUTHOR]

Hydrodynamic tools reveal information as to the behaviour of a device in the presence of waves but provide little information on how to improve or optimise the device. With no recent work on the transfer of power (energy flux) from a wave field through the body surface of a wave energy converter (WEC), we introduce the energy flux method to map the flow of power. The method is used to develop an open-source tool to visualise the energy flux density on a WEC body surface. This energy flux surface can also be used to compute the total power capture by integrating over the surface. We apply the tool to three WEC classes: a heaving cylinder, a twin-hulled hinged barge, and pitching surge devices. Using the flux surfaces, we investigate power efficiency in terms of power absorbed to power radiated. We visualise the hydrodynamic consequence of sub-optimal damping. Then, for two pitching surge devices with similar resonant peaks, we reveal why one device has a reduced power performance in a wave spectrum compared to the other. The results show the effectiveness of the energy flux method to predict power capture compared to motion-based methods and highlight the importance of assessing the flux of energy in WECs subjected to different damping strategies. Importantly, the tool can be adopted for a wide range of applications, from geometry optimisation and hydrodynamic efficiency assessment to structural design. [ABSTRACT FROM AUTHOR]

Global Climate Models (GCMs) are very essential and crucial for projecting future climate scenarios under different greenhouse gas emissions, incorporating uncertainties in the global warming projections. The present study evaluates the seasonal performance of 32 Coupled Model Intercomparison Project Phase 5 (CMIP5) models obtained from the Coordinated Ocean Wave Climate Project phase 2 (COWCLIP 2.0) in simulating the global and regional wave power (WP) from 1979 to 2004 using historical data, and comparing them against the ERA5 reanalysis. Three skill metrics, such as Root Mean Square Error (RMSE), Interannual Variability Skill (IVS), and M-Score were used to assess the model performance across three clusters (CSIRO, JRC, and IHC). In addition, Intra-seasonal and probability distribution is also employed to determine the cluster's performance, including individual models. The IHC cluster, employing statistical techniques, exhibited the lowest RMSE and highest M-Score values with the least variation among models over the global as well as regional ocean basins such as the North Atlantic (NA), North Pacific (NP), Indian Ocean (IO), and Pacific Ocean (PO. Results from intra-seasonal variability and probability distribution indicate that the IHC cluster demonstrates the most stable performance in simulating intra-seasonal variability of WP as compared to other clusters. [ABSTRACT FROM AUTHOR]

Wave energy converters (WECs) integrated into breakwaters present a promising solution for combining coastal protection with renewable energy generation, addressing both energy demands and environmental concerns. Additionally, this integration offers cost-sharing opportunities, making the overall investment more economically viable. This study explores the potential of a hinged point-absorber WEC, specifically designed as a floating hinged half-sphere, by assessing the device's power output and comparing two different breakwater configurations. To evaluate the device's performance, a comprehensive numerical and experimental approach was adopted. Numerical simulations were carried out using a radiation-diffraction model, a time domain tool for analyzing wave–structure interactions. These simulations predicted average power outputs of 25 kW for sloped breakwaters and 18 kW for vertical breakwaters located at two strategic sites: the Port of Leixões and the mouth of the Douro River in Portugal. To validate these predictions, a 1:14 scale model of the WEC was constructed and subjected to testing in a wave–current flume, replicating different sea-state conditions. The experimental results closely aligned with the numerical simulations, demonstrating a good match in terms of relative error and relative amplitude operator (RAO). This alignment confirms the reliability of the predictive model. These findings support the potential of integrating WECs into breakwaters, contributing to port energy self-sufficiency and decarbonization. [ABSTRACT FROM AUTHOR]

The decarbonization goals of each country necessitate the utilization of renewable resources, with photovoltaic (PV) and wind turbine (WT) generators being the most common forms. However, spatial constraints, especially on islands, can hinder the expansion of PV and WT installations. In this context, wave energy emerges as a viable supplementary renewable source. Islands are candidate regions to accommodate wave power resources due to their abundant wave potential. While previous studies have explored the wave energy potential of the Aegean Sea, they have not focused on the electricity production and techno-economic aspects of wave power facilities in this area. This paper aims to fill this knowledge gap by conducting a comprehensive techno-economic analysis to evaluate the feasibility of deploying an offshore wave power facility in the Aegean Sea, Greece. The analysis includes a detailed sensitivity assessment of CAPEX and OPEX variability, calculating key indicators like LCOE and NPV to determine the economic viability and profitability of wave energy investments in the region. Additionally, the study identifies hydraulic efficiency and CAPEX thresholds that could make wave power more competitive compared with traditional energy sources. The techno-economic analysis is conducted for a 45 MW offshore floating wave power plant situated between eastern Crete and Kasos—one of the most wave-rich areas in Greece. Despite eastern Crete's promising wave conditions, the study reveals that with current techno-economic parameters—CAPEX of 7 million EUR/MW, OPEX of 6%, a 20-year lifetime, and 25% efficiency—the wave energy in this area yields a levelized cost of energy (LCOE) of 1417 EUR/MWh. This rate is significantly higher than the prevailing LCOE in Crete, which is between 237 and 300 EUR/MWh. Nonetheless, this study suggests that the LCOE of wave energy in Crete could potentially decrease to as low as 69 EUR/MWh in the future under improved conditions, including a CAPEX of 1 million EUR/MW, an OPEX of 1%, a 30-year lifetime, and 35% hydraulic efficiency for wave converters. It is recommended that manufacturing companies target these specific thresholds to ensure the economic viability of wave power in the waters of the Aegean Sea. [ABSTRACT FROM AUTHOR]

The maritime industry is a major source of greenhouse gas (GHG) emissions, largely due to ships running on fossil fuels. Transitioning to hydrogen-powered marine transportation in the Mediterranean Sea requires the development of a network of hydrogen refueling stations across the region to ensure a steady supply of green hydrogen. This paper explores the technoeconomic viability of harnessing wave energy from the Mediterranean Sea to produce green hydrogen for hydrogen-powered ships. Four promising island locations—near Sardegna, Galite, Western Crete, and Eastern Crete—were selected based on their favorable wave potential for green hydrogen production. A thorough analysis of the costs associated with wave power facilities and hydrogen production was conducted to accurately model economic viability. The techno-economic results suggest that, with anticipated cost reductions in wave energy converters, the levelized cost of hydrogen could decrease to as low as 3.6 €/kg, 4.3 €/kg, 5.5 €/kg, and 3.9 €/kg for Sardegna, Galite, Western Crete, and Eastern Crete, respectively. Furthermore, the study estimates that, in order for the hydrogen-fueled ships to compete effectively with their oil-fueled counterparts, the levelized cost of hydrogen must drop below 3.5 €/kg. Thus, despite the competitive costs, further measures are necessary to make hydrogen-fueled ships a viable alternative to conventional diesel-fueled ships. [ABSTRACT FROM AUTHOR]

The maritime industry is a major source of greenhouse gas (GHG) emissions, largely due to ships running on fossil fuels. Transitioning to hydrogen-powered marine transportation in the Mediterranean Sea requires the development of a network of hydrogen refueling stations across the region to ensure a steady supply of green hydrogen. This paper explores the technoeconomic viability of harnessing wave energy from the Mediterranean Sea to produce green hydrogen for hydrogen-powered ships. Four promising island locations—near Sardegna, Galite, Western Crete, and Eastern Crete—were selected based on their favorable wave potential for green hydrogen production. A thorough analysis of the costs associated with wave power facilities and hydrogen production was conducted to accurately model economic viability. The techno-economic results suggest that, with anticipated cost reductions in wave energy converters, the levelized cost of hydrogen could decrease to as low as 3.6 €/kg, 4.3 €/kg, 5.5 €/kg, and 3.9 €/kg for Sardegna, Galite, Western Crete, and Eastern Crete, respectively. Furthermore, the study estimates that, in order for the hydrogen-fueled ships to compete effectively with their oil-fueled counterparts, the levelized cost of hydrogen must drop below 3.5 €/kg. Thus, despite the competitive costs, further measures are necessary to make hydrogen-fueled ships a viable alternative to conventional diesel-fueled ships.

AbstractThe focus is now on sustainable development, which is inevitable without harnessing renewable energy sources. The fundamental element in wind wave generation is the interaction between air and sea which helps in momentum exchange between atmosphere and ocean. The Indian coastline is under a dynamic wave climate with the action of wind. Indian landmass has two tropical basins, the Bay of Bengal and the Arabian Sea, which have tremendous potential to tap renewable energy. The variations in wave climate due to dynamic-wind have to be assessed. Hindcast data obtained from Global Climate Models help us in the long-term analysis of wind and wave climate. In an attempt to explore the renewable energy potential along the Indian coast, a numerical wave model is developed using MIKE 21 SW module to assess the wind and wave climate. A gridded global wind speed dataset from ECMWF called ERA-Interim wind speed data of 38 years (1981 to 2018) is used as input for the numerical model. The dataset and numerical model performance were validated against in-situ measurements. The results showed amongst the locations studied off Goa, Karnataka, Kerala, Tamil Nadu, and Andhra Pradesh had good potential to extract offshore wind energy using offshore wind turbines.

Coastal storms can cause erosion and flooding of coastal areas, often accompanied by significant social-economic disruption. As such, storm characterisation is crucial for an improved understanding of storm impacts and thus for coastal management. However, storm definitions are commonly different between authors, and storm thresholds are often selected arbitrarily, with the statistical and meteorological independence between storm events frequently being neglected. In this work, a storm identification algorithm based on statistically defined criteria was developed to identify independent storms in time series of significant wave height for high wave energy environments. This approach proposes a minimum duration between storms determined using the extremal index. The performance of the storm identification algorithm was tested against the commonly used peak-over-threshold. Both approaches were applied to 40 and 70-year-long calibrated wave reanalyses datasets for Western Scotland, where the intense and rapid succession of extratropical storms during the winter makes the identification of independent storm events notably challenging. The storm identification algorithm provides results that are consistent with regional meteorological processes and timescales, allowing to separate independent storms during periods of rapid storm succession, enabling an objective and robust storm characterisation. Identifying storms and their characteristics using the proposed algorithm allowed to determine a statistically significant increasing long-term trend in storm duration, which contributes to the increase in storm wave power in the west of Scotland. The coastal storm identification algorithm is found to be particularly suitable for high-energy, storm-dominated coastal environments, such as those located along the main global extratropical storm tracks. [ABSTRACT FROM AUTHOR]

Hydrodynamic tools reveal information as to the behaviour of a device in the presence of waves but provide little information on how to improve or optimise the device. With no recent work on the transfer of power (energy flux) from a wave field through the body surface of a wave energy converter (WEC), we introduce the energy flux method to map the flow of power. The method is used to develop an open-source tool to visualise the energy flux density on a WEC body surface. This energy flux surface can also be used to compute the total power capture by integrating over the surface. We apply the tool to three WEC classes: a heaving cylinder, a twin-hulled hinged barge, and pitching surge devices. Using the flux surfaces, we investigate power efficiency in terms of power absorbed to power radiated. We visualise the hydrodynamic consequence of sub-optimal damping. Then, for two pitching surge devices with similar resonant peaks, we reveal why one device has a reduced power performance in a wave spectrum compared to the other. The results show the effectiveness of the energy flux method to predict power capture compared to motion-based methods and highlight the importance of assessing the flux of energy in WECs subjected to different damping strategies. Importantly, the tool can be adopted for a wide range of applications, from geometry optimisation and hydrodynamic efficiency assessment to structural design.

The decarbonization goals of each country necessitate the utilization of renewable resources, with photovoltaic (PV) and wind turbine (WT) generators being the most common forms. However, spatial constraints, especially on islands, can hinder the expansion of PV and WT installations. In this context, wave energy emerges as a viable supplementary renewable source. Islands are candidate regions to accommodate wave power resources due to their abundant wave potential. While previous studies have explored the wave energy potential of the Aegean Sea, they have not focused on the electricity production and techno-economic aspects of wave power facilities in this area. This paper aims to fill this knowledge gap by conducting a comprehensive techno-economic analysis to evaluate the feasibility of deploying an offshore wave power facility in the Aegean Sea, Greece. The analysis includes a detailed sensitivity assessment of CAPEX and OPEX variability, calculating key indicators like LCOE and NPV to determine the economic viability and profitability of wave energy investments in the region. Additionally, the study identifies hydraulic efficiency and CAPEX thresholds that could make wave power more competitive compared with traditional energy sources. The techno-economic analysis is conducted for a 45 MW offshore floating wave power plant situated between eastern Crete and Kasos—one of the most wave-rich areas in Greece. Despite eastern Crete’s promising wave conditions, the study reveals that with current techno-economic parameters—CAPEX of 7 million EUR/MW, OPEX of 6%, a 20-year lifetime, and 25% efficiency—the wave energy in this area yields a levelized cost of energy (LCOE) of 1417 EUR/MWh. This rate is significantly higher than the prevailing LCOE in Crete, which is between 237 and 300 EUR/MWh. Nonetheless, this study suggests that the LCOE of wave energy in Crete could potentially decrease to as low as 69 EUR/MWh in the future under improved conditions, including a CAPEX of 1 million EUR/MW, an OPEX of 1%, a 30-year lifetime, and 35% hydraulic efficiency for wave converters. It is recommended that manufacturing companies target these specific thresholds to ensure the economic viability of wave power in the waters of the Aegean Sea.

The hybrid system of solar and wind is very useful in your day-to-day life. The various sources generally we are using likes sun energy, wave power generation, hydropower generation, tidewater power energy, and thermal gradient energy sources. This type of energy source is readily available in the environment and can consume maximum power from the actual solar panels and windmills. In this paper, we are using solar energy by using photovoltaic cells, and wind energy by using windmills generator. Solar and wind energy are cost-effective and easy to use. It can be used in mobile phones, Laptops, Daily Home appliances, and various types of lighting loads, which can be the best energy sources for urban, and rural, areas. As day by day, the electricity consumption is increased, because the demand has been increased day by day. We have to switch to other renewable energy sources and use the electricity from these sources. Power-Voltage and Current-Voltage characteristics of solar cell panels were accomplished at different values of irradiance and temperature levels of solar panels. [ABSTRACT FROM AUTHOR]

The focus is now on sustainable development, which is inevitable without harnessing renewable energy sources. The fundamental element in wind wave generation is the interaction between air and sea which helps in momentum exchange between atmosphere and ocean. The Indian coastline is under a dynamic wave climate with the action of wind. Indian landmass has two tropical basins, the Bay of Bengal and the Arabian Sea, which have tremendous potential to tap renewable energy. The variations in wave climate due to dynamic-wind have to be assessed. Hindcast data obtained from Global Climate Models help us in the long-term analysis of wind and wave climate. In an attempt to explore the renewable energy potential along the Indian coast, a numerical wave model is developed using MIKE 21 SW module to assess the wind and wave climate. A gridded global wind speed dataset from ECMWF called ERA-Interim wind speed data of 38 years (1981 to 2018) is used as input for the numerical model. The dataset and numerical model performance were validated against in-situ measurements. The results showed amongst the locations studied off Goa, Karnataka, Kerala, Tamil Nadu, and Andhra Pradesh had good potential to extract offshore wind energy using offshore wind turbines. [ABSTRACT FROM AUTHOR]

The direct drive Permanent Magnet Linear Generator (PMLG)-based Ocean Wave Energy Converters (OWECs) produce variable A.C. voltage. In this article, the variable A.C. voltage is converted into a variable D.C. voltage by a standard rectifier. After that, a buck–boost inverter is used to produce constant amplitude A.C. voltage at the load end. The buck–boost inverter, implemented here, operates in three modes: buck, boost, and buck–boost. Furthermore, a switching algorithm is developed to generate reference A.C. voltage. Systematic design of power converter, small-signal analysis, and PWM control strategy are discussed. The simulation results and results from a laboratory prototype are presented to support the theoretical concepts. [ABSTRACT FROM AUTHOR]

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Reliable access to drinking water and electricity can be a challenge, especially on islands. In this paper, desalination systems powered stand-alone by renewable energy sources are discussed, with a focus on wave power for the Swedish island Gotland. The objective is to evaluate the opportunity of using wave power for a desalination system on Gotland. The method includes assessing the electricity generation from a wave power park to power a desalination plant. The results show that the desalination plant would require 350 MWh annually, whereas the wave power plant could deliver 1891 MWh, supporting that it is technically feasible for a wave power park installed off the coast of Gotland to power a desalination plant.

This study investigated the historical and future wave power potential in the Gulf of Guinea (GoG) with the aim of identifying high-density wave energy locations for potential exploitation. To estimate wave power density (WPD) for three time periods (past: 1979–2005, mid-century: 2026–2050, and end-century: 2081–2100), we utilized significant wave height and mean wave period obtained from eight General Circulation Models. Using an ensemble of these WAVEWATCH III simulated datasets, we calculated WPD and assessed overall and seasonal trends, projecting changes under Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Results revealed higher potential WPD in the western GoG, particularly near the coast, with increased values offshore. Spatially, WPD change rates varied widely (−0.021 to 0.039 kW/m per year), suggesting both positive and negative trends, though generally low. Projections indicated a potential increase from 0.5 to 1.0 kW/m by the end of the century. The estimated potential power for harvesting exceeded 14,000 MW, with offshore regions showing better wave converter performance. This study concludes that GoG's wave energy is a promising renewable resource, offering a potential solution to future power needs and contributing to regional greenhouse gas emission mitigation.

In this work, an oscillating water column (OWC) device is considered placed in front of a V-shaped vertical breakwater. The idea conceived, is based on the amplified wave power absorption due to the wave interactions originating from the presence of the breakwater. A theoretical analysis is presented in the realm of linear potential theory, based on the solution of proper diffraction, and radiation problems in the frequency domain, using the eigenfunction expansion method, the method of images, and the multiple scattering approach. Optimum absorption efficiency is examined taking into consideration the characteristics of the power take off (PTO) system and the air compressibility. Numerical results are presented and discussed in terms of the expected power absorption. The effect of the distance between the OWC and the vertical walls, the breakwater's forming angle, and the wave heading angle, is examined to demonstrate the enhanced absorption ability of the device. It is concluded that the device's efficiency is strongly dependent on the position of the OWC in front of the walls, as well as the angle of the wave impact, and should be taken into account when determining the optimum device parameters for maximization of its performance. [ABSTRACT FROM AUTHOR]

There is a growing interest in extracting marine renewable energy and contributing in this way to the green road towards a low-carbon future. From this perspective, the Iberian nearshore represents a coastal environment with very high potential. In this context, the objective of the work proposed herewith is to perform a joint evaluation of the wave and wind power along the west Iberian coastal environment. The analysis is structured in two time intervals. The first is the 20-year period (2001–2020), for which the ERA5 wind data have been considered. The second 20-year period (2026–2045) corresponds to the near future and in this case, wind data provided by the climate model RCA4 (Rossby Centre regional atmospheric model, version 4) have been processed and analysed, corresponding to the climate scenario RCP4.5. (Representative Concentration Pathway). The same two periods have been considered for the evaluation of wave power. In this case simulations with spectral phase averaged model SWAN (Simulating WAves Nearshore) have been performed. This wave modelling system was implemented for the entire North Atlantic basin and focused on the west Iberian coastal environment. Finally, the results also indicate that there is a good synergy between wind and wave power in the west Iberian nearshore. As a conclusion, the development of joint wind–wave projects along the west Iberian coastal environment represents a viable direction for the near future. Especially, the Northwestern part of the Iberian nearshore has a very good potential both in terms of wave and wind energy.

The present study analyses the trend and variability in wave parameters (wave height and wave period) and wave power (WP) in the North Indian Ocean (NIO). The impact of climatic modes such as El‐Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on the WP of NIO has been investigated using the European Centre for Medium‐Range Weather Forecasts reanalysis datasets (ERA5) for the period 1959–2021. It is observed that along the west coast of India (WCI), the coastal WP increased from south to north during summer whereas, in winter and other seasons the WP increased from north to south. Instead, along the east coast of India (ECI), WP is higher on the north than the south, always. The annual WP climatology along the Indian coasts reveals that WP potential is higher along/adjacent to WCI than the ECI. It was observed that the total significant wave height (SWH) WP anomalies during normal and positive IOD (pIOD) events are mainly dominated by swell WP, whereas during El Niño and combined ENSO‐IOD events, dominated by wind seas. During the peak of pure El‐Niño, the SWH WP shows a basin‐wide increase in WP anomalies. However, during summer, SWH WP showed increasing trends over Bay of Bengal. It is evident from the composite analysis that annual averaged WP anomalies are decreasing in normal, pure pIOD and combined events, but El‐Niño is found to increase the WP anomalies over the Arabian Sea in the region north of 20°N. The present study advocates that a detailed analysis of WP along the Indian coastal regions is beneficial to the renewable energy industries to utilize this as an important energy resource. [ABSTRACT FROM AUTHOR]

This study presents a new wave energy converter that operates in two phases. During the first phase, wave energy is stored, raising a mass up to a design height. During the second phase, the mass goes down. When going down, it compresses air that moves a turbine that drives an electrical generator. Because of this decoupling, generators that move much faster than seawater can be used. This allows using "off-the-shelf" electrical generators. The performance of the proposed design was evaluated via simulations. As the device operates in two phases, a different simulation model was built for each phase. The mass-rising simulation model assumes regular waves. The simulation results suggest that energy harvesting is near the theoretical maximum. Mass falling is braked by air compression. Simulations of this system showed oscillatory behavior. These oscillations are lightly damped by the drag against the walls and air. These oscillations translate into generated power. Therefore, smoothing is needed to avoid perturbing the grid. A possible solution, in the case of farms comprising dozens of these devices, is to delay the generation among individual devices. In this manner, the combined generation can be significantly smoothed. [ABSTRACT FROM AUTHOR]

Mechanisms that control marsh edge erosion include wind‐generated waves, vegetation productivity, land use and land change, and geotechnical properties of sediments. However, existing models for predicting marsh edge evolution focus primarily on edge retreat rates as a function of wave energy while accounting for other controlling factors as empirical constants. This simplification arises from a lack of high‐frequency monitoring of marsh evolutions. In particular, marsh erosion is timescale dependent, and conducting field observations on short temporal and spatial scales could elucidate the progression of erosion, which may improve marsh erosion predictive models. This study developed and validated a near‐continuous camera and erosion pin monitoring system to document marsh edge erosion at a high frequency (i.e., daily) in Terrebonne Bay, Louisiana. This was supplemented with daily wave power to explore the relationships between daily erosion and wave power. Long‐term average erosion rates derived from satellite and aerial imagery from 1989 through 2019 compare similarly to rates derived from longer‐term site visits (i.e., monthly) at approximately 2.2 m/yr. High‐magnitude erosion events (>20 cm/day) are driven by a buildup in wave energy over a 7‐day time period coupled with a strong 1‐day wave event, indicating a gradual reduction in marsh edge resistance with continued wave attack. Long‐term erosion monitoring methods, including monthly field visits, provide results that align well with previously reported relationships between wave power and erosion. High‐frequency measurements, however, illustrate that the previously published trends smooth over the large‐magnitude short‐term erosion events, potentially obscuring the physical processes of marsh edge erosion. For example, satellite and aerial imagery provide a long period of record, but they may underestimate the average annual erosion rate in the region, the effect of which may become exasperated over the varying temporal scales considered in coastal planning efforts across the USA and worldwide. [ABSTRACT FROM AUTHOR]

Wave Energy is a type of renewable energy that uses the power of waves to generate electricity, and it is the largest estimated global resource form of ocean energy. This study deals with various techniques of wave power and focuses on the present scenario in the world and its potentiality in Bangladesh. The analysis of parameters of wave height, wavelength, and wave period; indicates the bright prospects of wave power in Bangladesh. [ABSTRACT FROM AUTHOR]

Integrating point absorber wave energy converters (PAWECs) and an offshore floating wind platform provide a cost-effective way of joint wind and wave energy exploitation. However, the coupled dynamics of the complicated hybrid system and its influence on power performance are not well understood. Here, a frequency-domain-coupled hydrodynamics, considering the constraints and the power output through the relative motion between the PAWECs and the semi-submersible platform, is introduced to optimize the size, power take-off damping, and layout of the PAWECs. Results show that the annual wave power generation of a PAWEC can be improved by 30% using a 90° conical or a hemispherical bottom instead of a flat bottom. Additionally, while letting the PAWECs protrude out the sides of the triangular frame of the platform by a distance of 1.5 times the PAWEC radius, the total power generation can be improved by up to 18.2% without increasing the motion response of the platform. The PAWECs can reduce the resonant heave motion of the platform due to the power take-off damping force. This study provides a reference for the synergistic use of wave and wind energy. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate long-term wave power (Pwave) trends over the Mediterranean Sea using innovative and classical trend analysis techniques, considering the annual and seasonal means. For this purpose, the data were selected for the ERA5 reanalysis with 0.5° × 0.5° spatial resolution and 1 h temporal resolution during 60 years between 1962 and 2021. Spatial assessment of the annual and seasonal trends was first performed using the innovative trend analysis (ITA) and Mann–Kendall (MK) test. To obtain more detailed information, innovative polygon trend analysis (IPTA), improved visualization of innovative trend analysis (IV-ITA), and star graph methods were applied to annual, seasonal, and monthly mean Pwave at 12 stations selected. The results allow us to identify an increasing trend above the 10% change rate with the innovative method and above the 95% confidence level with the Mann–Kendall test in mean wave power in the Levantine basin and the Libyan Sea at all timescales. The use of various innovative methods offered similar results in certain respects and complemented each other. [ABSTRACT FROM AUTHOR]

In this research, the evaluation of Ghana’s wave energy potential was presented based on the ERA5 monthly averaged data on single levels from 1979 to 2020 from European Centre for Medium-Range Weather Forecast (ECMWF). The data obtained which was the Significant Wave Height and Wave Period were used to calculate the Average Wave Power and Energy. The total wave power crossing the three divisions of Ghana’s coastline has been calculated to be 7215 MW. The calculated wave energy available was compared to the Annual Energy Demand of Ghana. The calculated value gives a clear picture that wave energy can be another renewable energy source in Ghana. This was done relying on data from a third-generation spectral wave model to simulate the wave conditions which were used to analyse the potential of the wave-generated energy of the selected coastal areas in Ghana.

In this article, the effectiveness of an U-shaped “oscillating water column wave energy converter device (OWC-WEC)” is investigated in a two-layer fluid system. To solve the BVP, the “dual boundary element method” (DBEM) is employed. Further, the response of shape parameters on the effectiveness of OWC-WEC is studied in “surface mode” (SM) and “internal mode” (IM), respectively. It is seen that in the surface mode, the variation in the efficiency curve as a consequence of the change in chamber’s length and the lip wall’s draft adopt a similar resonating pattern as in single layer fluid. Furthermore, negligible change is appeared in the efficiency curve due to the change in density ratios in SM mode. Moreover, for smaller and moderate wavenumbers, the variation in the efficiency curve due to the various chamber length, draft of the lip wall and density ratios in internal mode shows highly oscillatory behavior. In addition, this oscillatory behavior vanishes in the short-wave zone.

The switchless reluctance motor’s non-permanent magnet structure design ensures its high reliability in the marine environment; thus, it is a feasible solution for the generator of a sea wave power generation system. However, the corresponding thrust density and efficiency remain insufficient. This study focused on a new type of flat linear switched reluctance motor (LSRM), using the finite element software to establish a structural model, and optimized the design with the goal of improving the efficiency and energy density. The entropy method was adopted for sensitivity stratification to objectively select weights to avoid the influence of subjectively selected different proportional weights on the optimization results. Based on the entropy method, the sensitivity of different structural parameters was stratified, and the simulated annealing algorithm, response surface method, and single parameter scanning method were combined for optimization. Finally, the optimal structural size parameters of the motor were determined. Based on the two-dimensional finite element method, to simulate the electromagnetic performance of the reluctance motor under different operating conditions, such as thrust, loss, and efficiency, changes in motor performance before and after optimization were compared to verify the high power generation efficiency and energy density of the optimized linear motor.

This study investigates the annual average efficiency of the duct OWC-WEC in the regional irregular waves conditions. The OWC device is situated over a wrinkled bottom For the incident wave spectrum, the Bretschneider spectrum is used for the regional wave condition around the device plant. Further, the sea states associated with the regional wave condition in the site Pico, Portugal are considered. The yearly averaged efficiency of the duct OWC initially becomes higher when incident wavelength becomes shorter and reach to a maximum. Thereafter, the device efficiency declines for short waves. Further, for wider chamber, the efficiency becomes higher. For longer waves, the efficiency amplitude declines for higher front wall’s draft, and an opposite tendency is formed for moderate and smaller incident waves.

This study investigated the historical and future wave power potential in the Gulf of Guinea (GoG) with the aim of identifying high-density wave energy locations for potential exploitation. To estimate wave power density (WPD) for three time periods (past: 1979–2005, mid-century: 2026–2050, and end-century: 2081–2100), we utilized significant wave height and mean wave period obtained from eight General Circulation Models. Using an ensemble of these WAVEWATCH III simulated datasets, we calculated WPD and assessed overall and seasonal trends, projecting changes under Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Results revealed higher potential WPD in the western GoG, particularly near the coast, with increased values offshore. Spatially, WPD change rates varied widely (−0.021 to 0.039 kW/m per year), suggesting both positive and negative trends, though generally low. Projections indicated a potential increase from 0.5 to 1.0 kW/m by the end of the century. The estimated potential power for harvesting exceeded 14,000 MW, with offshore regions showing better wave converter performance. This study concludes that GoG's wave energy is a promising renewable resource, offering a potential solution to future power needs and contributing to regional greenhouse gas emission mitigation. [ABSTRACT FROM AUTHOR]

A wave energy converter features the ability to convert wave energy into the electrical energy required by unmanned devices, and its energy-conversion efficiency is an essential aspect in practical applications. This paper proposes a novel point-absorption wave energy converter with passive morphing blades to meet the demand for improved energy-conversion efficiency. We first introduce its concept and design, with its blades forming their shape by adaptive changes with the direction of the water flow. Next, the three-dimensional geometrical-morphing model, energy-conversion model, and energy-conversion-efficiency model of the wave energy converter were established. Then, the CFD model was built to optimize the design parameters, and the simulation results revealed that the maximum conversion efficiency can be obtained at 90% solidity with 10 blades, a 40–60% load, and 20~25 degrees for the external deflection angle. The simulations also showed that the passive morphing-blade group provides ~40% higher torque and ~60% higher hydraulic efficiency than the flat-blade group. [ABSTRACT FROM AUTHOR]

The combination of an offshore wind turbine and a wave energy converter on an integrated platform is an economical solution for the electrical power demand in coastal countries. Due to the expensive installation cost, a prediction should be used to investigate whether the location is suitable for these sites. For this purpose, this research presents the feasibility of installing a combined hybrid site in the desired coastal location by predicting the net produced power due to the environmental parameters. For combining these two systems, an optimized array includes ten turbines and ten wave energy converters. The mathematical equations of the net force on the two introduced systems and the produced power of the wind turbines are proposed. The turbines' maximum forces are 4 kN, and for the wave energy converters are 6 kN, respectively. Furthermore, the comparison is conducted in order to find the optimum system. The comparison shows that the most effective system of desired environmental condition is introduced. A number of machine learning and deep learning methods are used to predict key parameters after collecting the dataset. Moreover, a comparative analysis is conducted to find a suitable model. The models' performance has been well studied through generating the confusion matrix and the receiver operating characteristic (ROC) curve of the hybrid site. The deep learning model outperformed other models, with an approximate accuracy of 0.96. [ABSTRACT FROM AUTHOR]

The main objective of this study is to develop a fast and validated model to predict the motions' responses of a spar-buoy wave energy converter based on oscillating water column principle. Experiments and former investigations highlighted the strong effect of the spar-buoy heave motion on the performance of the OWC whereas water oscillations slightly affect the spar-buoy motions. Therefore, a single degree of freedom model was adopted to simulate the structure's surge, heave, and pitch responses separately. The prediction of the structure's heave and pitch responses is a straightforward task and results were experimentally validated and compared to previous studies. Linear and quadratic damping coefficients were introduced for better agreement between measured and predicted pitch responses. In contrast, surge response prediction task was more complicated as it requires the consideration of the mooring system installation properties, while the mooring configuration was not experimentally investigated since the reduced-scale model was floating freely (un-moored). Therefore, the predicted surge response obtained from the proposed model was validated using the finite element method. Two different approaches were used to solve the equation of motion in surge direction considering multi-catenary mooring system. Static approach where constant mooring-lines stiffness was used and a quasi-static approach where reaction curves developed were used to estimate the instant resultant mooring line tension at different offsets. Load excursion and reaction curves of the full-scale device developed by the proposed model were finally validated. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis of offshore wind and wave energy resources in mainland Portugal, aiming to facilitate sustainable energy exploitation. The study integrates the spatial distribution and temporal variability of those energy resources, as well as the interplay between wind and wave patterns and co-location feasibility. A 44-year dataset (1979–2022), derived from ERA5 reanalysis wind and SWAN wave model across the concession zones designated by the Portuguese government (labelled as P1 to P6) are utilised. The results indicate promising prospects for wind and wave power densities in these zones, emphasising the suitability of the offshore renewable energy extraction. Additionally, analysis revealed fluctuations in wind and wave power variability among the selected locations, with concession zone P3 (Leixões) emerging as a promising candidate due to its relatively lower variability and stable distribution patterns of both resources. The analysis on co-location feasibility demonstrated the potential for efficient energy extraction in location P5 proving to be the most favourable in wind-wave resource integration. Moreover, time lag analysis highlighted opportunities for optimising energy capture efficiency. Overall, this study provides valuable insights into the sustainable exploitation of wind and wave power resources, contributing to deliver informed decision-making for renewable energy investment. • Comprehensive evaluation of wind and wave resources along Portugal's coast. • Insights into 44-year spatial distribution patterns of wind and wave resources. • Assessing the complementary relation of wind and wave power resources. • Evaluating co-located energy harvesting in the offshore renewable concession zones. [ABSTRACT FROM AUTHOR]

Studies of arrays of wave energy converters (WECs) with respect to power absorption and array interactions are often performed using linear models. However, nonlinear effects can be important and may change power estimates and optimal array designs. In this study, we have compared linear predictions of the behaviour of a shallowly submerged, buoyant point absorber with predictions from the nonlinear model SWASH with a WEC incorporated (WEC-SWASH). The latter was first comprehensively validated against 1:20 Froude scaled measured data from physical experiments. WEC-SWASH predictions of body motions and mean power absorption were generally in good agreement with measurements (absolute bias within 25%), although some discrepancies were observed in the body motions, especially when the device exhibited motion instabilities. The validated WEC-SWASH model was then compared with a linear frequency-domain model, as the latter is well-known and widely used because of its computational efficiency. Model comparisons were carried out for both an isolated WEC and small arrays (up to 5 devices). The mean power estimates from the linear model and WEC-SWASH for two representative wave farms showed good agreement for mild waves, with a difference of less than 5%. However, for larger waves, the disagreement increased to about 75 to 85% between the models (for the two wave farms tested). We found that array interactions for these arrays depend on wave amplitude and not just wave frequency. Furthermore, we discovered that the power take-off coefficients optimized using the linear model were not the optimum coefficients for the nonlinear model (WEC-SWASH). • Comprehensive validation of a nonlinear model (WEC-SWASH) using experimental data. • Reanalysis of optimum conditions from linear model using nonlinear model. • Shape of the response curve in amplitude and frequency is different in WEC-SWASH. • The optimum power take-off coefficients also differ in the two approaches. [ABSTRACT FROM AUTHOR]

This study delves into the hydrodynamic performance of a bottom-seated U-shaped Oscillating Water Column (U-OWC) wave energy converter equipped with a pitching wall in the U-duct. Utilizing linear wave theory and the matched eigenfunction expansion method, a theoretical model has been developed to investigate the interaction between regular waves and this innovative U-OWC structure. The model's validity has been demonstrated through comparisons with published data, revealing strong agreement in terms of energy absorption efficiency, hydrodynamic coefficients, and wave dynamic pressure on the chamber wall's surface. Furthermore, the study examines the influence of the angle spring stiffness of the pitching wall, as well as variations in the U-duct's height and length, on the hydrodynamic performance of the U-OWC. The results emphasize the potential for optimizing the angle spring stiffness to achieve an ideal U-duct height and length, thereby significantly expanding the frequency bandwidth across a broad spectrum of wave conditions, in contrast to conventional fully-stationary U-OWC models. Crucially, the U-OWC model showcased improved wave energy absorption efficiency but increased wave loading compared to traditional bottom-mounted U-OWCs or conventional OWCs. It indicates that a trade-off should be satisfied in the practical application between the wave power extraction efficiency and the structural safety and durability. • A U-OWC with a pitching wall in the U-duct was studied theoretically. • The optimal dimensions of the U-duct that can broaden the frequency bandwidth were identified. • The performance of the proposed U-OWC was compared with other traditional OWC models. • The proposed U-OWC showed improved power absorption efficiency but increased wave loading. [ABSTRACT FROM AUTHOR]

Lacking a long-term power supply restricts the endurance of unmanned surface vehicles (USVs) and their application in remote sea areas. To address that ptoblem, a reliable solution based on the utilisation of wave energy is proposed in this study, where a wave-excited energy harvester is integrated into the USV. A fully coupled mathematical model is established to describe the dynamics and the electricity generation performance of the integrated system, considering the coupling of the mooring system. Numerical results given by this mathematical model are validated by physical experiments. The influence of the external load, the wave height, the wave period, the pendulum length, the pendulum mass and the mooring system on the system's performance are investigated, respectively. Experimental results of two small-scale prototypes, performed in a wave flume, show that the time-averaged generated electrical power is up to 324.89 mW when the wave height is 9.00 cm and the wave period is 1.72 s , where the corresponding wave-to-wire efficiency is 9.72%. Results indicate that the pendulum length, the pendulum mass, and the configuration of the mooring system significantly influence the resonant period and bandwidth. • A new wave-powered USV based on an inertial pendulum is proposed. • The proposed wave energy harvester has the capability to tune natural frequency. • A time-averaged electric power of 324.89 mW is achieved under a flume wave height of 9 cm. • The mooring system has a significant effect on the bandwidth of the USV. [ABSTRACT FROM AUTHOR]

Mitigating climate change requires a variety of energy technologies and energy simulation approaches to evaluate the best possible system structures. Screening whether novel technologies are a viable solution for a particular country within a cost-optimised system setup is usually simulation- and time-intensive. This study introduces the novel add-on optimisation tool EP-ALISON-LUT for use in combination with EnergyPLAN applied to the test case of wave power in the case of Seychelles in 2030 and 2050 within a structured sensitivity analysis. The tool enables a high number of possible system setups and scenarios, including the import and domestic production of electricity-based fuels, to be modelled, allowing for an in-depth view of the system impacts of integrating wave power. The results indicate a limited role for wave power due to its relatively low yield, especially in 2030. However, in 2050, up to 500 MW of wave power capacity is possible with a lower or similar levelised cost of final energy compared to the reference scenario in 2019, which can benefit the diversification of the power generation portfolio. Thus, this novel tool is fast and effective in technology screening studies requiring a fast optimisation algorithm. • Viability screening for novel renewable energy technologies is needed. • Novel optimisation tool based on and in combination with EnergyPLAN is presented. • Structured sensitivity analysis of wave power on the case of Seychelles is made. • Wave power can hardly challenge low-cost solar photovoltaics in the Sunbelt region. • Structured sensitivity analysis showed options for portfolio diversification. [ABSTRACT FROM AUTHOR]

Addressing the challenges linked to the high Levelised Cost of Electricity in ocean wave energy, the utilization of arrays comprising oscillating water columns (OWCs) emerges as a promising and preferred strategy. In this study, the efficacy of a linear OWC arrayed structure, comprising three identical cylindrical units embedded into an inclined breakwater, was demonstrated by leveraging the Computational Fluid Dynamics technique. The investigation delved into the potential impacts of varying the transverse spacing between the sub-units within the array and adjusting the slope profile. Comparisons were drawn between the integrated system – comprising an arrayed system and an inclined breakwater – and its equivalent embedded into a vertical breakwater under different water depth conditions owing to the influence of the tidal range. The results indicate that superior power extraction emerges when employing a larger transverse spacing, through amplifying the capture width ratio across a broader spectrum of wave frequencies, with a substantial 55.8% increment between the larger and smaller transverse spacing conditions. A moderate slope profile emerges as the favored choice for enhancing performance provided that the transverse spacing is to a larger extent. The advantageous performance of the arrayed system in contrast to the isolated structure, leveraging the principle of the q -factor, becomes more evident, particularly under a moderate slope profile. Additionally, the incorporation of an arrayed system into an inclined breakwater exhibits heightened potential for harnessing wave energy, particularly when stimulated by long-period waves, attributed largely to amplified wave scattering. Conversely, integration into a vertical breakwater excels within the domain of short-period waves. • A three-unit OWC array was explored by a Computational Fluid Dynamics model. • The performance of a linear array embedded into an inclined breakwater was shown. • An inclined breakwater with a moderate slope profile was a preferred design. • The scenarios embedded into an inclined and a vertical breakwater were compared. • Wave scattering played a significant role when embedded into an inclined breakwater. [ABSTRACT FROM AUTHOR]

The direct-drive Permanent Magnet Linear Generator (PMLG)-based Ocean Wave Energy Converter (OWEC) generates variable AC voltage, which cannot be directly utilized by the load. This paper presents a two-stage methodology to convert variable AC voltage to a constant amplitude AC voltage. First, a standard rectifier is used to convert variable AC voltage into variable DC voltage. After that, a cascaded buck-boost inverter is employed to achieve the constant frequency AC voltage. Systematic design and circuit analysis, along with working principle and voltage control strategy, are presented. A small scale laboratory prototype of PMLG associated with buck-boost inverter is developed to validate the proposed concept. [ABSTRACT FROM AUTHOR]

Wave energy is a new type of clean energy. Aiming at a low wave energy density and small wave height in China's coastal areas, a tubular permanent magnet linear generator (PMLG) with a short stroke, small volume, and high power density is designed for wave power generation. Firstly, the generator's electromagnetic parameters are analyzed by the analytical method, and the magnetic circuit topology and basic structure of the generator are analyzed by the equivalent magnetic circuit method (EMCM). Then, the finite element method (FEM) is used to analyze the influence law of the generator's basic structural parameters on the output electromotive force (EMF) and its sinusoidal characteristics. The multi-factor and multi-level analysis is carried out based on the orthogonal test method to study the size parameters of the above analysis, and the optimal structure parameter combination for the generator is obtained. Finally, the prototype is trial-produced and tested for steady-state and transient performance to confirm the accuracy of the simulation calculations, and the output performance under no-load and load conditions is examined. The results show that both the optimized prototype's power density and the output EMF's sinusoidal properties have been improved under the proposed scheme. [ABSTRACT FROM AUTHOR]