Changes In Wave Energy Research Articles

Predicted ecological consequences of wave energy extraction and climate-related changes in wave exposure on rocky shore communities

Abstract Wave energy has the potential to contribute in the transition to decarbonized electricity generation. Extracting wave energy might be expected to have ecological impacts on rocky shore intertidal communities where exposure is one of the most important factors determining species structure and composition. With global climatic change, coastal exposure is predicted to increase with greater significant wave height. The wave-exposed west coast of Orkney, Scotland, UK, is the site of pre-commercial wave device testing. Surveys of 39 rocky shore sites along this coast identified key species and abundances, and quantified exposure-modifying topographic variables. A spectral wave model was constructed to compare baseline, wave extraction, climate change, and combined scenarios. Generalized additive modelling was used to describe the relationship between species, topography, and exposure. Results show that individual species differentially respond to exposure changes with ‘winners’ and ‘losers’ at site level. Overall, community responses are expected to be far greater following predicted climatic change than to industrial-scale wave energy extraction, depending on spatial scale. In combination, energy extraction may reduce the effects of climate-change-related increases in wave exposure of rocky shores. Predicting how location-specific biotic assemblages respond to changes in wave energy as a result of long-term forcing agents provides a valuable marine resource management tool.

The impact of long-term changes in ocean waves and storm surge on coastal shoreline change: a case study of Bass Strait and south-east Australia

Abstract. Numerous studies have demonstrated that significant global changes in wave and storm surge conditions have occurred over recent decades and are expected to continue out to at least 2100. This raises the question of whether the observed and projected changes in waves and storm surges will impact coastlines in the future. Previous global-scale analyses of these issues have been inconclusive. This study investigates the south-east coast of Australia over a period of 26 years (1988–2013). Over this period, this area has experienced some of the largest changes in wave climate of any coastal region globally. The analysis uses high-resolution hindcast data of waves and storm surge together with satellite observations of shoreline change. All datasets have been previously extensively validated against in situ measurements. The data are analysed to determine trends in each of these quantities over this period. The coastline is partitioned into regions and spatial consistency between trends in each of the quantities investigated. The results show that beaches along this region appear to have responded to the increases in wave energy flux and changes in wave direction. This has enhanced non-equilibrium longshore drift. Long sections of the coastline show small but measurable recession before sediment transported along the coast is intercepted by prominent headlands. The recession is largest where there are strong trends in increasing wave energy flux and/or changes in wave direction, with recession rates of up to 1 m yr−1. Although this is a regional study, this finding has global implications for shoreline stability in a changing climate.

Morphodynamics of a composite sand-cobble beach in response to extratropical cyclone Fiona and seasonal wave variability

Climate change is driving higher coastal water levels, and models project accelerated future sea-level rise and coastal storm intensification. These dynamics paired with anthropogenic coastal alterations will drive drastic coastal change worldwide. Composite beaches with mixed sediment sizes warrant detailed study as these exhibit complex morphodynamics in response to changing hydrodynamics due to the distinct transport thresholds of different sediment types. This study uses a novel multi-method approach to investigate a composite sand-cobble beach in Atlantic Canada experiencing a shortening seasonal sand-covered period. Hydrodynamic forcing and associated beach changes were monitored over a focused eight-month period, while satellite-based visual imagery and reconstructed wave data were analyzed over longer periods. Results show that intra-annual wave energy changes drive sand dynamics, with reduced summer wave energy facilitating short-term deposition. Long-term positive trends were identified in late spring wave heights, which likely contribute to the shortening sand-covered period. Seasonal dynamics were overwhelmed by extratropical cyclone Fiona, which made landfall on September 24, 2022, generating significant wave heights up to 6.8 m in the bay, mobilizing sediment, and steepening cobble berms. A new index approach based on visual imagery facilitated the investigation of beach sand appearance/disappearance using the relative redness of sand compared to cobble. Finally, the UAV-based surveys yielded high-resolution orthomosaics and LiDAR-based elevation mapping, and highlighted pronounced longshore variability in erosion and deposition during Fiona. The beach mostly recovered to pre-storm conditions in <4 months, which indicates that proposed beach nourishment activities may only experience temporary success. The longer-term results showing a conversion of sand to cobble suggest that loss of sandy beach habitat is likely to increase, even without shoreline migration or coastal squeeze driven by sea-level rise.

Future electricity production at Mutriku Wave Energy Plant estimated from CMIP6 wave climate projections (2015–2100)

Renewable marine energy sources are rapidly developing worldwide. With numerous operational marine power plants in existence, it is becoming increasingly important to explore their potential. Hence, this study aims to examine the impact of climate change on the future potential of wave energy. The case study was centred on the Mutriku Wave Energy Plant, situated in the Bay of Biscay in the northern region of the Iberian Peninsula.To accomplish this, this study investigated changes in wave energy from 2015 to 2100 by employing ERA5 data and an ensemble of CSIRO wave projections driven by six distinct models derived from CMIP6 model runs. Two were associated with the SSP1-2.6 pathway while the other four corresponded to the SSP5-8.5 pathway. The unidimensional wave variables were bias-corrected using the Quantile Matching (QM) technique, whereas the bidimensional variables were corrected using the Multivariate Bias Correction N-pdf (MBC N-pdf) technique. Subsequently, a self-organising map (SOM) technique was employed to classify daily sea type frequencies and power. Additionally, the Smirnov test was employed to determine whether the probability density functions derived from different datasets exhibited significant differences at a significance level of 0.05.The conclusions obtained indicate that energy production in the Bay of Biscay will remain stable in the late 21st Century. The daily frequencies of the sea type and power did not change significantly. This stability ensures consistent power generation, enabling the location to provide a reliable and consistent source of energy both currently and in the future.

GRANULOMETRIC ANALYSIS OF PALEOTSUNAMI DEPOSITS CANDIDATE IN TERNATE ISLAND, NORTH MALUKU

Ternate Island is a volcanic island located in the Maluku Sea. Tsunami ever hit Ternate before 1900 or occurred before the age of the people living in this island. The paleotsunami suspect have been found in the western coast of Ternate Island. The outcrop has 50 m length and 1 m width, was discovered beneath the Gamalama eruption product which occurred in 1907. The paleotsunami candidate consists of at least five layers originating from different tsunami events. The granulometric analysis was carried out for each layer. The results obtained were that paleotsunami sediments had poorly sorted which indicated that the grain sizes were mixed, this was due to the energy of tsunami wave varied in time when transporting and depositing the sediments. Skewness varies from very fine to very coarse, indicating a change in the energy of the tsunami wave that occurs from very high when rising inland to decreasing as it returns to sea. Kurtosis varies from leptokurtic, platykurtic, and mesokurtic. Variations in mean, sorting, skewness and kurtosis values indicate a change in tsunami wave energy which causes a change in grain size. The granulometric analysis shows that the deposition of the youngest paleotsunami deposits candidate was initiated by a very strong current with the greatest energy, thus depositing very coarse sand to gravel, followed by a gradual decrease in energy and the tsunami wave process began to reverse towards the sea, then receded with the lowest energy and deposited finer grains. The sediment sources come from two different places, this shows that the sources come from the sea and the coast around the deposited paleotsunami candidates.

Laminar boundary layers and damping of finite amplitude solitary wave in a wave flume

In this paper, the laminar viscous effects on finite amplitude solitary wave propagation in a wave flume with a rectangular cross section are investigated. The laminar viscous effects are most important in the laminar boundary layers adjacent to the bottom and sidewalls of the flume. The closed-form solutions of Clamond and Fructus [“Accurate simple approximation for the solitary wave,” C. R. Mec. 331, 727 (2003)] provide the free stream velocity to derive the boundary layer flows. The rotational velocities inside the bottom and sidewall boundary layers are first obtained analytically after linearization. Numerical solutions for the nonlinear boundary layer flows are also calculated. The importance of the nonlinearity is discussed. The laminar viscous damping rate is estimated by balancing the energy dissipation inside the boundary layers and the rate of wave energy change in the entire wave. Numerical results of the damping rate show the dependence on the viscosity of the fluid, the wave amplitude, the water depth, and the width of the wave flume. New laboratory experiments on the wave damping of finite amplitude solitary waves are also performed. The theoretical results are confirmed with the laboratory data. The methodologies introduced in this paper for obtaining boundary layer solutions and laminar viscous damping rate can be applied to other transient waves with finite amplitude.

Propagation of Dirac waves through various temporal interfaces, slabs, and crystals

We investigate the influence of the temporal variations of various medium parameters on the propagation of Dirac-type waves in materials where the quasiparticles are described by a generalized version of the pseudospin-1/2 Dirac equation. Our considerations also include the propagation of electromagnetic waves in metamaterials with the Dirac-type dispersion. We focus on the variations of the scalar and vector potentials, mass, Fermi velocity, and tilt velocity describing the Dirac cone tilt. We derive the scattering coefficients associated with the temporal interfaces and slabs analytically and find that the temporal scattering is caused by the changes of the mass, Fermi velocity, and vector potential, but does not arise from the changes of the scalar potential and tilt velocity. We also explore the conditions under which the temporal Brewster effect and total interband transition occur and calculate the change in total wave energy. We examine bilayer Dirac temporal crystals where parameters switch between two different sets of values periodically and prove that these systems do not have momentum gaps. Finally, we assess the potential for observing these temporal scattering effects in experiments.

Optimal Selection among Various Three-Phase Four-Wire Back-to-Back (BTB) Converters with Comparative Analysis for Wave Energy Converters

Wave energy converters are attracting attention as an energy source that can respond to climate change. In order to increase the energy efficiency of the wave energy converters, efficient power converters are also required. The efficient converters require operation at a low switching frequency, which increases the weight and volume of the passive components. Therefore, in this paper, the performance of various types of topologies is compared to select the optimal power converter for wave energy converters. In order to cope with the unbalanced operation and unbalanced load of renewable energy, in this paper, the topology of the four-leg type is analyzed centrally. In addition, the analysis was performed by applying the model predictive control that can quickly respond to the rapid energy change of wave energy. In addition, model predictive control was applied to the four-leg converter analyzed in this paper because it is suitable for application to atypical topologies. For performance analysis of various types of topology, the loss and efficiency of each converter were analyzed by applying a loss analysis model, and output current harmonics and leakage current characteristics, capacitor voltage fluctuation rate, etc., were additionally analyzed at various switching frequencies. In conclusion, the three-level four-leg converter showed up to 2.28% and 2.7% higher efficiency under balanced and unbalanced operating conditions.

Assessing Drivers of Coastal Tundra Retreat at Point Hope, Alaska

AbstractShoreline erosion over the last few decades along the Point Hope, Alaska, USA coastline has led to considerable loss of tundra behind the beach. Analysis of available remote sensing, morphology, and hydrodynamic datasets are used to inform the time scales and mechanisms of coastal land loss at Point Hope, in part through integration of these data into an analytical retreat model originally developed for coastal foredunes. At shorter time scales, these analyses indicate that steeper local beach slopes influence higher wave runup that can enhance the scale of tundra retreat at a particular section of coast. Coastal stretches that are most vulnerable to wave attack of the tundra scarp appear to shift with time related to complex spatio‐temporal variability in shoreline change rates. These local beach erosion rates primarily control the retreat of the tundra at decadal scales. However, independent of the fronting beach morphology, the largest erosion events throughout the region generally occur when there is the coincidence of both high wave energy and elevated still water levels. Additional exploratory modeling results indicate that future changes to sea level and changes in wave energy will further enhance the magnitude of tundra erosion.

Editorial: Offshore wind and wave energy and climate change impacts

Editorial: Offshore wind and wave energy and climate change impacts

Assessing the Role of Extreme Mediterranean Events on Coastal River Outlet Dynamics

River mouths are highly dynamic environments responding very rapidly to changes in wave energy or river floods. While the morphological response during floods or during marine storm events has been widely documented in the literature, little is known about the mechanisms acting during the co-occurrence of fluvial and marine hazards. This concomitance of river flood and marine storm is quite common in the western Mediterranean Sea, and was the case for the Gloria event, considered to be the most extreme event in recent decades. During this event, monitoring of hydrodynamics and morphological evolution was implemented, making it possible to better understand the impact of concomitant marine storm and fluvial flood during an extreme meteorological event on spit breaching of a small Mediterranean river mouth. Monitoring using a combination of high-resolution hydrodynamic measurements, topographic and bathymetric surveys, and sediment cores was used before, during, and after the storm “Gloria”. The results suggest an amplification of the morphological impact of the events and a different morphogenic response than if each of the events had acted independently on the system. The marine storm, occurring first, weakened the spit and initiated its breaching, which was continued by the extreme fluvial flood, thus leading to the complete destruction of the mouth. The destruction of the spit acted as a sediment source for subaqueous large delta deposition amounting to 50% of the total volume. The contribution of the river, estimated at 30%, was quite low for an exceptional event, showing the importance of locating rainfall in a catchment area controlled by a dam. For this event, extreme morphological evolution was observed, as well as the importance of water levels in the river mouth, which probably increased flood hazards, demonstrating the importance of including the compounding effect of extreme coastal water levels in river flood risk management.

Assessment of coastal variations due to climate change using remote sensing and machine learning techniques: A case study from west coast of India

Climate change and other environmental disturbances are causing sea level rise all over the world. Due to sea-level rise and other unprecedented atmospheric phenomena caused by climate change, Indian coasts are vulnerable to coastal erosion. The Kerala coast, at the southern tip of India's west coast, has experienced a sea change in the last decade. To address coastal variations, we investigate coastal erosion, coastal accretion, and shoreline changes (from 2006 to 2020) along this coast between Pozhiyoor and Anchuthengu (58 km). To monitor the status and predict changes along the coast, remote sensing, GIS, field checks, and machine learning tools were used. The data analysis reveals that the shoreline configuration, rate of beach accretion, and erosion have all changed significantly. When the rate of erosion in the 58-km-long coastal stretch was examined, it was discovered that approximately 42 km face acute erosion, 13 km face accretion, and approximately 3 km face neither accretion nor erosion and remain in equilibrium. According to the estimates, approximately 2.62 km2 of land has been eroded away from the shore over a 14-year period, while 0.7 km2 of land has been accreted. At locations where the influence of river discharge or groynes is minimal, the normal rate of accretion in the stretch is around 1–2 m/y. Nonetheless, the rate of accretion increased to 5–8 m/y where groynes or river mouths, or both, have a significant influence on shoreline stability. The normal rate of erosion in the stretch under consideration, however, is around 5 m/y. With a rate of 10.59 m/y, Pozhiyoor had the highest erosion rate. According to the data, the rate of erosion is faster between Pozhikkara and Veli. The increase in shoreline changes is primarily may be due to increased cyclone occurrences in the Arabian Sea, the formation of swell waves, changes in wave energy, and sea level rise due to climate change. The slow rate of sediment discharge by rivers, groyne construction, groyne spacing, groyne length, long shore currents, and preferential northward sediment transport all play a role in the formation and destruction of beaches along India's west coast. Using machine learning techniques, a prediction model for the year 2027 was created using data from the previous 14 years (2006–2020). According to the model, almost the entire stretch will experience severe erosion, with the rate remaining consistently high between Shanghumugham and Anchuthengu. As a result, soft and appropriate engineering solutions are required for coastal stability all along the beach, particularly at these two locations after a feasibilty study.

Relative sea level and wave energy changes recorded in a micro-tidal barrier in southern Brazil

AbstractConstructional sedimentary history of coastal barriers can provide insights regarding meteorological and oceanographic processes, and relative sea-level changes. We investigated the Holocene evolution of a segment of the Rio Grande do Sul Coastal Plain in southernmost Brazil. Data were obtained from ground-penetrating radargrams, optically stimulated luminescence dating, altimetry measurements, Google Earth imagery, and aerial photographs. These data allowed a qualitative and quantitative analysis of the beach profiles recorded in the radargrams. From which eolian, backshore/foreshore, breaker bars, and upper and lower shoreface radar facies were identified. The beach-related radar facies are recorded in twenty-eight progradational sand units (sigmoidal bodies). These units record increments of relatively steady deposition bounded by erosional surfaces produced by anomalous, high-magnitude storm events taking place about every 250 years. The upper shoreface strata include two to three breaker bars. Several pieces of evidence (number of breaker bars, upper shoreface gradient and progradation rate) suggest an alternation between dissipative and intermediate stages of barrier morphodynamics and a decrease of wave energy from 2 ka onwards. The barrier prograded during the last 7.1 ka, and initially, barrier progradation occurred because of a normal regression during a relative sea-level rise followed by a stillstand. Later, barrier progradation took place as a forced regression driven by a relative sea-level fall.

Future Changes of Atmospheric Energy Cycle in CMIP5 Climate Models

AbstractFuture changes in the atmospheric energy cycle were estimated by using 12 climate models from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) and mass‐weighted isentropic zonal‐mean framework. In this framework, the zonal‐mean available potential energy (AZ) is converted to the zonal‐mean kinetic energy (KZ) through mean‐meridional direct circulations, and KZ is converted to the wave energy (W), the sum of eddy available potential energy and eddy kinetic energy, through wave‐mean flow interactions. The comparison between the late 21st century in a high emission scenario and the late 20th century in the historical scenario indicates a significant increase in AZ and KZ in winter in the Northern Hemisphere (NH) and the Southern Hemisphere (SH). The wave energy significantly decreases in the NH winter but slightly increases in the SH winter. In the NH winter, the stationary wave energy significantly decreases, and the transient wave energy shifts poleward. Global warming reduces the baroclinic instability wave activity, which suppresses the upward Eliassen‐Palm flux and wave‐induced extratropical direct circulation. It decreases the dynamic energy conversion rates C(AZ, KZ) and C(KZ, W). On the other hand, the diabatic wave energy generation rate (QE) is projected to increase, particularly in the SH. The future W change is consistent with the change in the sum of C(KZ, W) and QE. Changes in both the dynamical energy conversion associated with wave‐mean flow interactions and the generation of eddy available potential energy associated with diabatic heating processes are necessary to explain the wave energy change.

Wave variability along the world’s continental shelves and coasts: Monitoring opportunities from satellite Earth observation

Insight on wave regimes along the world’s coastlines is important for virtually all coastal and nearshore marine activities, installations, planning and protection. Waves are pervasive and the dominant source of energy driving extreme sea levels, the transport of pollutants and sediments, erosion, and a major contributor to risks of flooding. We quantify the global spatio-temporal wave conditions along the world’s coasts and evaluate the needs for coastal Earth Observation strategies, with the aim, notably, that the derived scales of change can contribute to optimisation of these strategies. A global dominant timescale of 30 days is found in coastal wave variability that is, on average, spatially correlated just over the synoptic 5 degrees’ regional scale (≈ 550 km at the equator). This regional-scale dimension suggests that the timing and design of traditional field surveys and observations relevant to a vast array of coastal activities, and which may be expensive in terms of human resources, may be complemented by information gained from satellite Earth Observation that throws light on spatio-temporal scales of wave-energy change along the world’s coastlines.

Wave Power Density Hotspot Distribution and Correlation Pattern Exploration in the Gulf of Mexico

Wave energy has been studied and explored because of its enormous potential to supply electricity for human activities. However, the uncertainty of its spatial and temporal variations increases the difficulty of harvesting wave energy commercially. There are no large-scale wave converters in commercial operation yet. A thorough understanding of wave energy dynamic behaviors will definitely contribute to the acceleration of wave energy harvesting. In this paper, about 40 years of meteorological data from the Gulf of Mexico were obtained, visualized, and analyzed to reveal the wave power density hotspot distribution pattern, and its correlation with ocean surface water temperatures and salinities. The collected geospatial data were first visualized in MATLAB. The visualized data were analyzed using the deep learning method to identify the wave power density hotspots in the Gulf of Mexico. By adjusting the temporal and spatial resolutions of the different datasets, the correlations between the number of hotspots and their strength levels and the surface temperatures and salinities are revealed. The R value of the correlation between the wave power density hotspots and the salinity changes from −0.371 to −0.885 in a negative direction, and from 0.219 to 0.771 in a positive direction. For the sea surface temperatures, the R values range from −0.474 to 0.393. Certain areas within the Gulf of Mexico show relatively strong correlations, which may be useful for predicting the wave energy behavior and change patterns.

Response of wave energy to tidal currents in the western sea of Jeju Island, Korea

This study focuses on the changes in wave energy in response to tidal currents in the western sea of Jeju Island where high-energy wave conditions along with strong tidal currents are usual. Here, an ocean-wave coupled modeling system was used to investigate the effect of tidal currents on the wave energy condition. A comparative experiment with and without tidal currents shows that the current largely affects wave energy in terms of the wave spectrum as a response to the relative direction between waves and currents. When the direction of the tidal current is the same as that of wave propagation, the magnitude of wave height is reduced with energy transfer from shorter periods of 7–9 s to longer periods of 10–12 s, resulting in a decrease (increase) of shorter (longer) wave energy. This reaction is reversed when the tidal current flows in a direction opposite to that of wave propagation. The uncoupled model tends to overestimate/underestimate the wave energy during the ebb/flood tides when the waves follow/oppose the currents by approximately 25%. This study demonstrates that ocean-wave coupling is capable of improving model wave conditions, and therefore, this model is useful for estimating potential wave energy resource and candidate sites.

Surfzone-beach-dune interactions along a variable low wave energy dissipative beach

The different possible factors that influence or drive the observed volumetric and morphological variation in foredunes located along 16 km of a low wave energy, dissipative southern section of the 190 km long Younghusband Peninsula (South Australia) are examined. Grain size, wind energy, coastline orientation, and vegetation species presence/absence vary only slightly along this coast providing a unique site to study other drivers of coastal change. Results show that foredune height and volume progressively increase towards the north coincident with a gradual increase in wave energy. A significant correlation between foredune volume and wave energy is established, while no apparent relationship with other controlling factors was found, confirming the importance of wave energy in the dune building process on wave-dominated beaches. Results indicate that (1) all other factors being equal, wave energy can drive the morphological evolution of foredunes; (2) minor changes in wave energy can result in differences in the long-term beach and dune sediment budget; and, (3) the surfzone-beach-dune interactions model is applicable to coasts with small scale gradients in wave energy.

A climate-dependent sustainability index for wave energy resources in Northeast Asia

In this study, five decades of simulated wave climate in Northeast Asia were used to investigate the intra-annual variation and long-term change of wave energy potential. The results show that in general, the nearshore areas of the eastern Pacific side of Japan have the highest annual mean wave power while Japan and Taiwan function as natural barriers to prevent oceanic waves to propagate from the Pacific Ocean towards Korea and eastern China. The wave energy hotspots vary, seasonally mainly from the east of Japan during the spring to Ryukyu Islands and Taiwan during the autumn, with the highest values in nearshore areas reach around 40 kW/m in September. The results indicate that the intra-annual stability of wave energy resources is the lowest in the western coasts of Japan, whereas this area has contained the least change of wave energy during five decades. On the contrary, southern areas of Japan despite having higher monthly stability show the highest reduction of wave power in the long-term. Hence, a novel index was proposed and applied in nearshore areas in order to specify the most suitable areas for wave energy exploitation considering the sustainability of the resources in both short and long-term.

The influence of tidal jet current – Ocean wave interaction on the embayed beach processes

Many embayed beaches are formed by barriers that block embayments to create barrier-enclosed estuaries. These embayed beaches are characterized by strong tidal jets that drain the estuaries through a tidal inlet, often debouching at one end. A field study was conducted on Buffalo Beach in Mercury Bay (Waikato, New Zealand) to study wave energy changes caused by the ebb tidal jet. Acoustic Doppler Current Meter observations showed that during peak ebb jet flow, a decrease in wave height occurred along the beach sites that were in close proximity to the ebb jet. A DELFT3D hydrodynamic and wave model was used to further show that wave height variance was due to the jet current causing shoaling and refraction between the central beach and inlet adjacent southern beach. The resulting wave energy focused along the southern beach, diverged along the central beach and increased the alongshore radiation stress gradient. Under modeled storm conditions within the bay, when wave heights exceed 1.5 m, the jet was found to increase spreading and overall jet width. The jet orientation was also deflected shoreward towards the inlet adjacent headland. The radiation stresses driving alongshore transport became increasingly dominant with increased wave height, suggesting that alongshore sediment mobility increases substantially during a storm event due to the presence of the jet. Implications are that jet strength and orientation play a role in embayed beach rotation.