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The potential energy associated with tides presents a sustainable energy resource that remains largely untapped. Uncertainties on the economic case of tidal range power plants are a known obstacle. Research on tidal range structures suggests energy yield may be maximized through operation strategy optimization, and that impacts can be mitigated through design optimization. While instructive, these perspectives alone are insufficient to support the feasibility of individual projects. We integrate operation optimization and hydrodynamic impact analyses within a cost evaluation framework for tidal range structures focusing on capital costs (CAPEX) and levelized cost of energy (LCOE). Once benchmarked against 11 historic proposal cost projections, we perform a redesign of 18 tidal power plants to deliver a comprehensive comparative basis across a diverse range of sites in the UK. Tidal power plant operation is simulated in regional shallow-water equation models, acknowledging tide variability. The cost evaluation framework demonstrates the impact of geospatial variations on key cost components. The redesign process indicates transformative implications in that equivalent and lower LCOE values can be achieved for designs at a substantially lower CAPEX. Given how the latter hinder development, we show how tidal range schemes could be far more economically feasible than commonly perceived. [ABSTRACT FROM AUTHOR]

Ocean energy, e.g., waves, tidal current, and thermal and salinity gradient, can be used to produce electricity. These marine-based renewable energy technologies are at relatively early stages of development and potentially deployed at various sea conditions. In the past, numerous studies were undertaken to explore the feasibility of harvesting of the marine energy in Malaysia; however, those studies were limited to a specific location (i.e., the east coast of Peninsular Malaysia and East Malaysia) and the consideration of sea level rise effect was not studied. This study assessed the potential of tidal and wave energy resources in Malaysia's waters with the effect of projected sea level rise and was undertaken through numerical modeling using MIKE 21 software. The research outcomes were tidal and wave energy contours for Malaysia's waters with an inclusion of the sea level rise projection for 2060 and 2100, as well as a potential site determined for tidal and wave energy harvesting. The simulation results highlight the significant potential of tidal and wave energy in specific locations around Malaysia and its coastal regions, as well as in the South China Sea's offshore regions. By incorporating sea level rise projections into tidal and wave simulations, we revealed a notable increase in tidal and wave power. [ABSTRACT FROM AUTHOR]

Testing and research centres for offshore renewable energy, exemplified by facilities like BIMEP (Biscay Marine Energy Platform) on the Basque coast of Spain, play a crucial role in driving the energy transition. This study utilises pre-existing data at the facility site, such as high-resolution bathymetry and granulometric information from sediment samples, to conduct a comprehensive geological analysis including both sedimentary and rocky seabed. A litho-structural analysis is presented, including a lithological prediction for the continental shelf, the recognition of the main structures, such as NW-trending folds and predominantly NE-SW oriented fractures, and a detailed fracture analysis. Sedimentary seabeds are analysed through a Seabed Sediment Map, illustrating a granulometry-based NE-SW oriented banded distribution. Bedforms are also studied, they are asymmetric and mainly oriented NE-SW. The Seabed Sediment Map and the bedform analysis reveal the effect of an SE-directed bottom current as the main mechanism controlling sediment mobility. This current matches with the predominant swell from the NW and with the direction of the most energetic waves in the area. This approach could serve as a methodological example, offering a cost-effective means for the preliminary geological characterisation of offshore energy sites, and is crucial for establishing a baseline ('zero state') before the deployment. This baseline is essential for evaluating and mitigating the impact of new infrastructure on sediment dynamics, which subsequently affects the overall functioning and health of the marine ecosystem. [ABSTRACT FROM AUTHOR]

Wave energy holds significant promise as a renewable energy source due to the consistent and predictable nature of ocean waves. However, optimizing wave energy devices is essential for achieving competitive viability in the energy market. This paper presents the application of a nonlinear model predictive controller (MPC) to enhance the energy extraction of a heaving point absorber. The wave energy converter (WEC) model accounts for the nonlinear dynamics and static Froude–Krylov forces, which are essential in accurately representing the system's behavior. The nonlinear MPC is tested under irregular wave conditions within the power production region, where constraints on displacement and the power take-off (PTO) force are enforced to ensure the WEC's safety while maximizing energy absorption. A comparison is made with a linear MPC, which uses a linear approximation of the Froude–Krylov forces. The study comprehensively compares power performance and computational costs between the linear and nonlinear MPC approaches. Both MPC variants determine the optimal PTO force to maximize energy absorption, utilizing (1) a linear WEC model (LMPC) for state predictions and (2) a nonlinear model (NLMPC) incorporating exact Froude–Krylov forces. Additionally, the study analyzes four controller configurations, varying the MPC prediction horizon and re-optimization time. The results indicate that, in general, the NLMPC achieves higher energy absorption than the LMPC. The nonlinear model also better adheres to system constraints, with the linear model showing some displacement violations. This paper further discusses the computational load and power generation implications of adjusting the prediction horizon and re-optimization time parameters in the NLMPC. [ABSTRACT FROM AUTHOR]

Recent research revealed the potential of tidal energy in the central coastal region of the Colombian Pacific. Buenaventura City, located in the Valle del Cauca department in Colombia, has an important opportunity to develop tidal power technologies near its marine coastal areas. This research implemented a 3D hydrodynamic model for simulating the hydrodynamics of the Buenaventura Bay to provide data as input for evaluating the hydraulics of a tidal barrage without sluicing through CFD modeling. According to the results, the velocities across the gates during Syzygy (April 2021) showed impressive velocities between 9 and 11 m/s, which suggest a high possibility of producing electricity through tidal turbines. The mean behavior of velocities in the gates pointed to values of 3 and 5 m/s in most of the cases. The results during the Stoa condition were interesting because flow velocities higher than 1 m/s were not expected. This is promising because the plant might produce electricity even during the Stoa condition. For the first time, the results of this research suggest that there exists a high possibility of implementing tidal barrage plants in Buenaventura City, Colombia. [ABSTRACT FROM AUTHOR]

Numerous offshore wave energy converter (WEC) designs have been invented; however, none has achieved full commercialization so far. The primary obstacle impeding WEC commercialization is the elevated levelized cost of energy (LCOE). Consequently, there exists a pressing need to innovate and swiftly diminish the LCOE. A critical challenge faced by WECs is their susceptibility to extreme wave loads during storms. Promising concepts must demonstrate robust design features to ensure resilience in adverse conditions, while maintaining efficiency in harnessing power under normal sea states. It is anticipated that the initial commercial endeavors will concentrate on near-shore WEC technologies due to the cost advantages associated with proximity to the coastline, facilitating more affordable power transmission and maintenance. In response, this manuscript proposes a pioneering near-shore WEC concept designed with a survivability mode that is engineered to mitigate wave loads during severe sea conditions. Moreover, prior investigations have highlighted favorable resonance properties of this novel concept, enhancing wave power extraction during recurrent energetic sea states. This study employs numerical and physical modelling techniques to evaluate wave loads on the proposed WEC. The results indicate a remarkable 65% reduction in wave loads on the moving floater of the WEC during a range of sea states under the implemented survivability mode. [ABSTRACT FROM AUTHOR]

Ocean energy sources are a promising source of energy. However, simulating a hydrokinetic farm with multiple units requires significant computational resources, while physical experimentation on site is expensive. Therefore, the scientific challenge is to develop analytical and experimental tools that consider real aspects of areas with generation potential in a controlled laboratory environment. This paper presents a theoretical and experimental tool for analysing the interconnection of a hydrokinetic energy farm comprising 20 generation units. The test bench is a Power Hardware in the Loop type, consisting of one physical prototype generator to scale and 19 discrete averaged models operating in real-time. The system allows generators to interact through an amplifier, emulating the impact of power injection in a small electrical network. This is based on the variability of the marine resource, specifically the current velocities in the Cozumel-Mexico channel. Unlike other publications, the most significant contribution of this work is a complete feasible emulation of a marine current plant interconnected to an electrical grid, where the objective is to have a global analysis of the operation of each generation unit and the impact of the interconnection as a whole, considering that such information is of utmost importance for the execution of future projects of power generation from the sea. [ABSTRACT FROM AUTHOR]

Battiau-Queney, Y.; Ventalon, S.; Abraham, R.; Sipka, V.; Cohen, O., and Marin, D., 2024. Bedforms and sedimentary features related to water-depth variations in a sandy tidal-flat environment. Journal of Coastal Research, 40(1), 80–103. Charlotte (North Carolina), ISSN 0749-0208. This study highlighted the variability of a wide sandy macrotidal coastal system on short timescales. Changes in water depth and exposure length were the main drivers of this variability. In the study area, the coastal system consists of three units: a lower ridge-and-runnel beach, a 1000-m-wide tidal flat, and a sandy backshore. This research is based on sedimentary features that can record physical forces, especially the bedforms at the beach surface, and their relationship with beach gradient, exposure length, and changing water depth, according to tidal, weather, and marine conditions. It also demonstrated the ability of scanning electron microscope analysis of quartz grain microtextures to indicate the level of marine and eolian energy in the coastal system. The widespread wave and current sand ripples on the tidal flat showed great variability in time and space. A minimum water depth of 0.30 to 0.50 m was required for their development. The role of wind-induced waves and the frequent interference of tidal, wave, and wind forcing mechanisms are emphasized. The development of some complex sand ripples extended over a complete lunar tidal cycle. Wind-generated sand ripples were observed only on the backshore. Their absence on the tidal flat, despite the high level of eolian energy attested by quartz microtextures, and the poor development of dunes on the backshore are explained by factors impeding eolian sand transport at the beach surface such as extreme fetch segmentation and possible shell armoring of the beach surface during dry periods. This study demonstrated the short-term variability of the beach morphology as opposed to the long-term stability of the coastal system as a whole, in which the ultradissipative tidal flat, characterized by limited sand supply, low wave energy, and high but inefficient wind energy, plays a key role. [ABSTRACT FROM AUTHOR]

Energy harvesting from Vortex-Induced Vibration (VIV) presents a promising avenue for renewable energy generation by harnessing the kinetic energy of fluid flows through innovative technologies. Despite the increasing interest in VIV energy harvesting, there is a need for a systematic evaluation of the existing literature to understand the research trends, key contributors and emerging areas of focus. A bibliometric analysis offers a quantitative approach to address this gap, providing valuable insights into the evolution and dynamics of research on energy harvesting from VIV. The analysis employs VOSviewer software to analyze publication data retrieved from Scopus, focusing on publication trends, top authors, subject area, top citation, popular keywords, co-authorship countries' collaboration and network mapping based on citation by country. By examining publication patterns, citation counts and collaboration networks, this study aims to uncover underlying patterns and identify critical factors driving research in this field. The bibliometric analysis reveals a significant upward trend in research activity, with a notable increase in publications from recent years, indicating growing interest and recognition of VIV energy harvesting. In conclusion, this bibliometric analysis provides valuable insights into the research trends, key contributors and collaborative networks in energy harvesting from VIV. The findings guide for both academic and industrial , facilitating informed decision-making and driving progress toward sustainable energy solutions. This study also lays the groundwork for future research directions and interdisciplinary collaborations aimed at maximizing the potential of VIV energy harvesting for renewable energy generation. [ABSTRACT FROM AUTHOR]

Tidal stream energy is a predictable renewable energy source; however, environmental consent of developments remains a key barrier to the expansion of this industry. Uncertainty around collision risk, i.e., the risk of animals colliding with a tidal device, remains a major barrier to consent. Collision risk models are used in environmental impact assessments. Common collision risk models, like the Encounter Rate and Band Models, have limitations in accommodating new device designs and flexibility. To address this, a simulation-based approach was developed. To provide confidence in its use, it is important that the simulation-based approach is compared against the Band model and the Encounter rate model, which have been regularly used in the UK. Here, we compared collision risk estimates from the three models under the same exact conditions and one alternative condition. The results of the main scenario (where all conditions were the same) showed that the three models produced comparable results with <6% difference across all models. However, for the alternative scenario, the simulation-based approach produced a result three times higher compared to other models, which could not account for a vertical approach angle. These findings provide confidence in the simulation-based approach whilst also outlining the importance of selecting an appropriate collision risk model, tailored to the specific assessment scenario. Improved understanding and application of such models hold the key to more accurate risk evaluations in environmental impact assessments, thus facilitating the sustainable development of the tidal energy industry. [ABSTRACT FROM AUTHOR]

Marine current energy converters such as tidal and riverine turbines have the potential to provide reliable, clean power. The risk of collision of fishes with marine energy turbines is not yet well understood, in part due to the challenges associated with observing fish at turbine sites. Turbidity and light availability can limit the effectiveness of optical sensors like video cameras, motivating the use of acoustic cameras for this task. However, challenges persist in collecting and interpreting data acquired from acoustic cameras. Given the limited number of turbine deployments to date, it is prudent to draw on the application of acoustic cameras to monitor fish in other scenarios. This article synthesizes their use for other fisheries applications to inform best practices and set realistic expectations for the results of acoustic camera monitoring at turbine sites. We discuss six key tasks performed with acoustic cameras: detecting objects, identifying objects as fish, counting fish, measuring fish, classifying fish taxonomically and analysing fish behavior. Specific challenges to monitoring fish at turbine sites are discussed. This article is intended to serve as a reference for researchers, regulators and marine energy developers on effective use of acoustic cameras to monitor fish at turbine sites. The studies detailed in this article provide evidence that, in some scenarios, acoustic cameras can be used to inform the risk of fish collision with marine energy turbines but doing so requires careful study design and data processing. [ABSTRACT FROM AUTHOR]

Due to the rapid development of today's industry, it not only greatly accelerates the consumption of energy, but also causes serious pollution to the environment. Therefore, reducing energy waste and recovering energy has become an important research direction today. This paper introduces the future development trend of renewable energy, discusses the progress of recovery of nonpolluting energy such as marine, bioenergy and thermal energy, and analyzes the efficiency and social benefits of various types of energy recovery. Energy recovery methods for natural gas pipelines are briefly analyzed, and current research advances in energy pressure recovery devices are provided, leading to a summary of methods to improve the efficiency of fluid energy recovery. Finally, it is concluded that although the current energy sources are diversified, the most valued energy sources at present and in the future should be solar energy and ocean, which are infinitely recyclable. This paper will benefit researchers to further understand and study the various aspects of energy recovery. [ABSTRACT FROM AUTHOR]

The interactions between marine wildlife and marine energy devices are not well understood, leading to regulatory delays for device deployments and testing. Technologies that enable marine wildlife observations can help to fill data gaps and reduce uncertainties about animal–device interactions. A validation test conducted in Galveston Bay near La Porte, Texas, in December 2022 used a technology package consisting of a tethered balloon system and three independent sensor systems, including three-band visible, eight-band multispectral, and single-band thermal to detect three marine-mammal-shaped surrogates. The field campaign aimed to provide an initial step to evaluating the use of the TBS and the effectiveness of the sensor suite for marine wildlife observations and detection. From 2 December to 7 December 2022, 6 flights were conducted under varying altitudes and environmental conditions resulting in the collection of 5454 images. A subset of the images was classified and analyzed with two collection criteria including Beaufort wind force scale and TBS altitude to assess a range of observations of a surrogate from near-shore to offshore based on pixel count. The results of this validation test demonstrate the potential for using TBSs and imaging sensors for marine wildlife observations and offer valuable information for further development and application of this technology for marine energy and other blue economy sectors. [ABSTRACT FROM AUTHOR]

The transient acceleration of ocean currents, or internal waves, is hard to detect, because it does not have climate variability or regular manifestation in the sea. This fluctuation affects not only short-term oceanographic processes but also the hydrokinetic generation of power and the structural health of ocean technologies. Identifying and understanding the mechanisms that generate internal waves require long-term data on the kinetic and viscous–turbulent parameters of the water column measured over long intervals. In this sense, this study analyzed current profiles in nearshore waters (8.9 m depths) measured over six months in the Colombian Caribbean Sea and found internal waves due to the manifestation of transient acceleration propagating in two of the three layers of the water column. The analyzed time series of currents and turbulent kinetic profiles evidenced that transient waves occurred during changes in the surface winds. The applied methodology in this research allowed, for the first time in the study area, the detection of transient accelerations (±0.25 m/s2) that modified the hydrokinetic energy of the water column over short-term periods (6–24 h). [ABSTRACT FROM AUTHOR]

The lagoon is a natural system protected from the sea by a dune barrier creating energy from the movement of rising and falling tides, thus providing a sustainable option for extracting energy from tidal currents. The energy that can be extracted is one of the most potential renewable energy sources. Therefore, the interaction of tidal currents with stratification layers has become important to optimize the efficiency of energy conversion at each depth layer in water masses. We have chosen as a case study, the Oualidia lagoon (Atlantic coast of Morocco). This ecosystem is characterized by hydrodynamics relatively favored by tides and tidal currents which are the main intra-lagoon currents, with a predominance of the semi-diurnal component M2 (period of 12 h 25) with 2.1 to 3.4 m of tidal range. The Multicell Argonaut-XR ADCP is used to measure the current velocity in the Oualidia lagoon at three different stations to study tidal patterns in a vertical layer of water depth. At each station, current velocities were recorded in each 0.5 m layer over a depth of about 5 m. As a result, this study showed that current velocity measurements to be used as renewable energy are found at station 1 located at a depth of 3.5 meters (~layer 5) with a current velocity of 0.771 m/s and a power density value of 235.344 W/m², station 2 located at a depth of 3.5 meters (~layer 5) with a current velocity of 0.4 m/s and a power density value of 32.86 W/m² and station 3 is located at a depth of 3 meters (~layer 6) with a current velocity of 0.527 m/s and a power density value of 75.157 W/m². The variation in current velocities between the different stations is mainly influenced by tides (Flood/ebb), the period of the measurements and the location of the stations. This work presents a model for extracting electrical energy through the use of tidal and current flow variations in such semi-enclosed natural system including lagoons. [ABSTRACT FROM AUTHOR]

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The marine energy (ME) industry historically lacked a standardized data processing toolkit for common tasks such as data ingestion, quality control, and visualization. The marine and hydrokinetic toolkit (MHKiT) solved this issue by providing a public software deployment (open-source and free) toolkit for the ME industry to store and maintain commonly used functionality for wave, tidal, and river energy. This paper demonstrates an initial model verification study in MHKiT. Using Delft3D, a numerical model of the Tanana River Test Site (TRTS) at Nenana, Alaska was created. Field data from the site was collected using an Acoustic Doppler Current Profiler (ADCP) at the proposed Current Energy Converter (CEC) locations. MHKiT is used to process model simulations from Delft3D and compare them to the transect data from the ADCP measurements at TRTS. The ability to use a single tool to process simulation and field data demonstrates the ease at which the ME industry can obtain results and collaborate across specialties, reducing errors and increasing efficiency. [ABSTRACT FROM AUTHOR]

Vortex-induced vibration (VIV) of bluff bodies is one type of flow-induced vibration phenomenon, and the possibility of using it to harvest hydrokinetic energy from marine currents has recently been revealed. To develop an optimal harvester, various parameters such as mass ratio, structural stiffness, and inflow velocity need to be explored, resulting in a large number of test cases. This study primarily aims to examine the validity of a parameter optimization approach to maximize the energy capture efficiency using VIV. The Box–Behnken design response-surface method (RSM-BBD) applied in the present study, for an optimization purpose, allows for us to efficiently explore these parameters, consequently reducing the number of experiments. The proper combinations of these operating variables were then identified in this regard. Within this algorithm, the spring stiffness, the reduced velocity, and the vibrator diameter are set as level factors. Correspondingly, the energy conversion efficiency was taken as the observed value of the target. The predicted results were validated by comparing the optimized parameters to values collected from the literature, as well as to our simulations using a computational-fluid dynamics (CFD) model. Generally, the optimal operating conditions predicted using the response-surface method agreed well with those simulated using our CFD model. The number of experiments was successfully reduced somewhat, and the operating conditions that lead to the highest efficiency of energy harvesting using VIV were determined. [ABSTRACT FROM AUTHOR]

Recognizing that innovation in renewable energy generation is an effective way to improve sustainable energy generation, the government and industries in the G7 states have invested heavily in the development of novel green technologies related to ocean energy generation. Irrespective of this, the existing literature has failed to explore the nexus between innovation in innovation in ocean generation-related technologies (IOEGT) and carbon dioxide emissions (CO2e). This paper contributes to the environmental economics by looking at the linkage between IOEGT and CO2e, with the international collaboration in green technology development (ICGTD), gross domestic product per capita (GDPPC), expansionary monetary policy (EMP), expansionary commercial policy (ECM), contractionary monetary policy (CMP), renewable energy consumption (REC), and contractionary commercial policy (ECM) in the G7 states from 1990 to 2020. The Westerlund and Edgerton (2008) test validated the long-run association among IOEGT, EMP, ECM, ICGTD, CMP, REC, ECM, GDPPC, and CO2e. The cross-sectional-autoregressive-distributed lag estimators found the following main findings. First, IOEGT is a helpful tool for reducing CO2e. Second, ICGTD and REC were associated with a lower level of CO2e. Third, EMP and ECP contribute to an increase in carbon emissions. However, CCP and CMP are essential to the long-term reduction of CO2e. Fourthly, GDPPC exacerbates the negative effects of CO2e. [ABSTRACT FROM AUTHOR]

This paper addresses the current status and future research and development perspectives associated with technologies to harness offshore renewable energy, including offshore wind, waves, tides, ocean currents, and thermal and salinity gradient, in South America (SA). It focuses on five countries: Argentina, Brazil, Chile, Colombia and Uruguay. At first, a comprehensive survey presents the number of scientific papers classified based on the resource to show the tendency and importance of such subjects in the academic community. Each country's electricity matrix and grid connection are shown to understand the region's renewable source participation situation. The potential of offshore renewable resources is addressed by considering the published technical papers in scientific journals. The main conflicts and synergies associated with ocean space utilization are presented by considering the exclusive economic zone of each country. The status of the regulatory frameworks to promote and development of offshore renewable energies is presented. Two sections are dedicated to presenting the active, decommissioned and planned projects, research groups and laboratory infrastructures to develop the technologies. The last section discusses the future perspectives on the development of this sector in SA. It is observed that SA, with more than 25,000 km of coastline, has a great potential for offshore renewable energy; however, so far, these resources have not been explored commercially. Larger investment in the sector, establishing an adequate legal framework and deploying full-scale demonstration projects at sea are necessary for the commercialization of such technologies in SA. [ABSTRACT FROM AUTHOR]

Analysis of the very-low-sulfur fuel oil (VLSFO) and ultra-low-sulfur fuel oil (ULSFO) bunkered in key ports in Asia, the Middle East, North America, Western Europe, and Russia is presented. The characteristics of said fuels, including density, sulfur content, kinematic viscosity, aluminum and silicon content, vanadium and nickel content, as well as pour point are investigated. Furthermore, the main trends and correlations are also discussed. Based on the graphical and mathematical analysis of the properties, the composition of the fuels is predicted. The key fuel components in Asian ports, the most important of which is Singapore, are hydrodesulfurized atmospheric residues (AR) (50–70%) and catalytic cracker heavy cycle oil (HCO) (15–35%) with the addition of other components, which is explained by the presence of a number of large oil refining centers in the area. In the Middle East ports, the most used VLSFO compositions are based on available resources of low-sulfur components, namely hydrodesulfurized AR, the production facilities of which were recently built in the region. In European ports, due to the relatively low sulfur content in processed oils, straight-run AR is widely used as a component of low-sulfur marine fuels. In addition, fuels in Western European ports contain on average significantly more hydrotreated vacuum gas oil (21%) than in the rest of the world (4–5%). Finally, a mixture of hydrotreated (80–90%) and straight-run fuel oil (10–15%) with a sulfur content of no more than 2.0–2.5% is used as the base low-sulfur component of marine fuels in the ports of Singapore and the Middle East. [ABSTRACT FROM AUTHOR]

This document is an editorial published in the journal Frontiers in Marine Science. It discusses the importance of developing renewable energy from the ocean to address economic development and climate change. The editorial highlights the various disciplines involved in marine energy development, such as marine biology, chemistry, ecology, and the environment. It also summarizes ten peer-reviewed articles published in the journal, which cover topics such as seabed flow, seabed properties, offshore structures, and the effects of fish-turbine interactions. The editorial concludes by emphasizing the significance of addressing marine (renewable) energy for a better world. [Extracted from the article]

With Malaysia being surrounded by water bodies, tidal energy could be used for energy extraction. While several turbine designs and technologies have been used for tidal energy extraction, information on the use of vertical-axis tidal turbines (VATTs) for shallow-water applications is scarce. However, implementing horizontal-axis tidal turbines (HATTs) is not feasible due to Malaysian ocean depths. Hence, examining the wake-flow characteristics of VATTs in a shallow water-working environment in Malaysia is essential. The wake turbulence of the Savonius turbine model was compared with that of a hypothetical 'actuator' cylinder, a VATT representation. Subsequently, the wake turbulences of a Savonius turbine model in static and dynamic simulations were compared to understand the flow distinction. Compared with that exhibited by the hypothetical actuator cylinder of 2.5 m, the hypothetical actuator cylinder of 5 m exhibits greater velocity deceleration. Additionally, the modelled Savonius turbine exhibits significantly more deceleration than that exhibited by the hypothetical actuator cylinder. Finally, the analysis of the static model of the Savonius turbine shows deceleration that is greater than that of the dynamic model. [ABSTRACT FROM AUTHOR]

Fossil fuel depletion, climate change, and increased global energy demands are the driving forces to find alternative sources of energy. Marine-based biorefinery has been recently discussed as a promising route to mitigate the environmental challenges, enhance the energy recovery, and provide a potential source for value-added products. Anaerobic digestion is a promising technology that can convert the organic compounds of marine ecosystems into biogas. To date, a comprehensive review incorporating integrated biogas potential and effective approaches to enhance seaweed digestibility for biogas production from marine resources has not been reported. Thus, the present review aims to explore and comprehensively present seaweed and other marine resources for potential biogas production. The basics and challenges of biogas production from seaweed are elucidated. The impact of biochemical composition on biogas and the microbial communities involved in anaerobic digestion of seaweed are discussed. Utilization of different techniques such as pretreatment, co-digestion, and sequential extraction of seaweed biomass to enhance the biogas yield and to mitigate the effect of inhibitors are presented. Specifically, this article evaluates the co-digestion of seaweed with other biomass feedstocks or liquid biowastes. Integration of marine microalgae cultivation on anaerobic digestate for value-added compound production, biogas upgrading, and bioenergy recovery provides a promising approach towards a zero-waste marine-based system. [ABSTRACT FROM AUTHOR]

This paper presents the economic feasibility analysis of a 2 MW Ocean Thermal Energy Conversion (OTEC) power plant in the open cycle. The plant can supply 6.35% of the average annual consumption of the electricity demand located at San Andrés Island (Colombia). On the one hand, the work presents the selection of the place to locate an offshore facility considering the technical viability while, on the other hand, the economic viability analysis is performed. The latter considers two scenarios: one without desalinated water production and another one with desalinated water. In this way, it is intended to first determine its construction's technical requirements to analyse its economic performance. This approach allows us to have a general idea of the implementation costs and the benefits obtained with this type of plant, for the particular case of San Andrés, an island in the Colombian Caribbean with sustained stress on electricity production and freshwater generation. The results obtained show that the technology is viable and that the investment can be recovered in an adequate time horizon. [ABSTRACT FROM AUTHOR]

Unknowns around the environmental effects of marine renewable energy have slowed the deployment of this emerging technology worldwide. Established testing methods are necessary to safely permit and develop marine energy devices. Magnetic fields are one potential cause of environmental effects and are created when electricity is generated and transmitted to shore. Further, the existing variation of the background magnetic field at sites that may be developed for marine energy is largely unknown, making it difficult to assess how much additional stress or impact the anthropogenic magnetic field may have. This study investigates two instruments for their ability to characterize the background magnetic fields at a potential marine energy site in Sequim Bay, WA. Based on this evaluation, this study recommends an Overhauser magnetomer for assessing the background magnetic field and demonstrates the use of this sensor at a potential marine energy site. [ABSTRACT FROM AUTHOR]

Acoustic emissions from current energy converters remain an environmental concern for regulators because of their potential effects on marine life and uncertainties about their effects stemming from a lack of sufficient observational data. Several recent opportunities to characterize tidal turbine sound emissions have begun to fill knowledge gaps and provide a context for future device deployments. In July 2021, a commercial-off-the-shelf hydrophone was deployed in a free-drifting configuration to measure underwater acoustic emissions and characterize a 25 kW-rated tidal turbine at the University of New Hampshire's Living Bridge Project in Portsmouth, New Hampshire. Sampling methods and analysis were performed in alignment with the recently published IEC 62600-40 Technical Specification for acoustic characterization of marine energy converters. Results from this study indicate acoustic emissions from the turbine were below ambient sound levels and therefore did not have a significant impact on the underwater noise levels of the project site. As a component of Pacific Northwest National Laboratory's Triton Field Trials (TFiT) described in this Special Issue, this effort provides a valuable use case for the IEC 62600-40 Technical Specification framework and further recommendations for cost-effective technologies and methods for measuring underwater noise at future current energy converter project sites. [ABSTRACT FROM AUTHOR]

Marine energy devices must be attached to the seafloor by their foundations, pilings, or anchors, and will have other parts in the water column like the devices themselves, mooring lines, and power export cables running along the seafloor. The installation and presence of these artificial structures will create physical changes that can disrupt or create new habitats, and potentially alter the behavior of mobile organisms such as fish around a device by attracting them to these new artificial reefs and fish aggregating devices. In this study, we tested a new approach for monitoring fish activity around a marine energy device anchor: a 360-degree underwater camera to keep the target (a wave energy converter's anchor) in the field of view of the camera. The camera was deployed in three configurations (hand-held, tripod, video lander) at sites with different hydrodynamics and underwater visibilities. The video lander was the best configuration: very stable, versatile, and easy to handle. The 360-degree field of view enabled observing and counting fishes, which were more abundant at dusk than dawn or noon, around the anchor. Despite remaining challenges, 360-degree cameras are useful tools for monitoring animal interactions with marine energy devices. [ABSTRACT FROM AUTHOR]

Recommendations derived from papers documenting the Triton Field Trials (TFiT) study of marine energy environmental monitoring technology and methods under the Triton Initiative (Triton), as reported in this Special Issue, are summarized here. Additionally, a brief synopsis describes how to apply the TFiT recommendations to establish an environmental monitoring campaign, and provides an overview describing the importance of identifying the optimal time to perform such campaigns. The approaches for tracking and measuring the effectiveness of recommendations produced from large environmental monitoring campaigns among the stakeholder community are discussed. The discussion extends beyond the initial scope of TFiT to encourage discussion regarding marine energy sustainability that includes life cycle assessment and other life cycle sustainability methodologies. The goal is to inspire stakeholder collaboration across topics associated with the marine energy industry, including diversity and inclusion, energy equity, and how Triton's work connects within the context of the three pillars of energy sustainability: environment, economy, and society. [ABSTRACT FROM AUTHOR]

A diversified energy portfolio may include marine energy in the form of current energy converters (CECs) such as tidal or in-river turbines. New technology development in the research stage typically requires monitoring for environmental effects. A significant environmental effect of concern for CECs is the risk of moving parts (e.g., turbine blades) colliding with animals such as fishes. CECs are installed in energetic locations in which it is difficult to operate sensors to fulfill monitoring requirements for informing collision risk. Collecting data (i.e., about blade strikes or near-misses) that inform interactions of fishes with CECs is usually attempted using active acoustic sensors or video cameras (VCs). Limitations of low-light conditions or water turbidity that preclude effective use of VCs are overcome by using high-resolution multibeam echosounders (or acoustic cameras (ACs)). We used an AC at two sites to test its ability to detect artificial and real fish targets and determine if strike, near-miss, and near-field behavior could be observed. Interactions with fish and artificial targets with turbines have been documented but strike confirmation with an AC is novel. The first site was in a tidal estuary with a 25 kW turbine and water clarity sufficient to allow VC data to be collected concurrently with AC data showing turbine blade strike on tethered artificial fish targets. The second site was a turbid, debris-laden river with a 5 kW turbine where only AC data were collected due to high water turbidity. Data collection at the second site coincided with downstream Pacific salmon (Oncorhynchus spp.) smolt migration. Physical fish capture downstream of the turbine was performed with an incline plane trap (IPT) to provide context for the AC observations, by comparing fish catches. Discrimination between debris and fishes in the AC data was not possible, because active movement of fishes was not discernable. Nineteen fishes were released upstream of the turbine to provide known times of possible fish/turbine interactions, but detection was difficult to confirm in the AC data. ACs have been used extensively in past studies to count large migratory fish such as Pacific salmon, but their application for small fish targets has been limited. The results from these two field campaigns demonstrate the ability of ACs to detect targets in turbid water and observe blade strikes, as well as their limitations such as the difficulty of distinguishing small fishes from debris in a high-energy turbid river. Recommendations are presented for future applications associated with CEC device testing. [ABSTRACT FROM AUTHOR]

Marine energy is poised to become an important renewable energy contributor for the U.S., but widespread deployment of the technology hinges on its benefits outweighing the potential ecological impacts. One stressor marine energy installations introduce is light, which is known to cause varying responses among wildlife and has not yet been addressed as an environmental concern. This review discusses requirements and regulations for similar structures and how lighting design choices can be made to meet these requirements while minimizing environmental consequences. More practical guidance on implementing lighting for marine energy is needed, as well as updated guidelines to reflect technological and research advances. Known responses of wildlife to light are introduced in addition to how the responses of individuals may lead to ecosystem-level changes. The impact of light associated with marine energy installations can be reduced by following basic guidance provided herein, such as removing excess lighting, using lights with high directionality, and employing controls to reduce light levels. Continued research on animal responses to light, such as findings on minimum light levels for animal responses, alongside the development of highly-sensitivity spectral characterization capabilities can further inform lighting guidelines for deploying future open ocean marine energy devices. [ABSTRACT FROM AUTHOR]

The growing global demand for sustainable and environmentally friendly energy has stimulated the rapid adoption of renewable offshore energy. However, infrastructure needed for green energy production ironically impacts upon marine species and biodiversity. Consequently, this positional review paper seeks to comprehensively synthesise the prevailing body of knowledge on the impact of offshore energy development on a broad range of marine species. An interpretivist philosophical stance and inductive reasoning was adopted using scientometric analysis to conduct a rich synthesis of extant literature. From an operational perspective, the Scopus database was utilised to search for key terms on the phenomena under investigation and using the VoS Viewer software for the identification of trends using scientometric maps. The analysis reveals that research in this area of science has increased significantly over the last decade but private sector involvement is conspicuous by its absence. Primary concerns among the research community include the impact of energy development on the abundance of species, pollution and biodiversity behaviour and migration. At present, researchers have extensively focused on the impact of offshore wind farms on fish and marine mammals. However, the literature reveals no significant long-term impact upon energy development on most marine species albeit, short-term interference has raised concerns (from sound, disruption of navigation and foraging patterns, and damage of habitat). To minimise short term disruption, researchers have recommended the use of acoustic deterrence during construction, enforcement of protected areas and continued research. [ABSTRACT FROM AUTHOR]

Power technology has long been the main problem that has plagued the realization of ocean exploration by autonomous underwater vehicles (AUVs). This paper introduces a new wave energy conversion device for AUV, which is sealed inside a closed floating body to avoid interaction with the marine environment. The system uses the gyroscopic effect to continuously convert the pitching motion of waves into electrical energy through flywheel rotation, and thus theoretically extend the endurance time of AUVs. In this paper, a mathematical model of the power generation device is established, and the effects caused by different parameters on the system behavior and energy output are analyzed. In order to reduce the cost of experiments, the energy conversion device is installed on an experimental platform that can simulate wave motion to observe its energy generation performance. The experimental results show that the established mathematical model can accurately reflect the real behavior of the power generation device on the platform under different wave conditions, and the energy output error is only 9.91%. [ABSTRACT FROM AUTHOR]

In 2015, Bali Province is mandated by ESDM ministry to become the National Region of Clean Energy, promoting efforts to explore new source of electricity namely tidal stream energy. Previous works have demonstrated that Toyapakeh Strait contains a promising tidal stream resource, with a high stream in a long period. In this study, hydrodynamic modelling and power production analysis is conducted to evaluate this potential with an aim to meet energy demand of Tiga Nusa Cluster Islands. Twenty-one Gen5 KHPS turbines are employed in this study, at an optimized location, 8.72°S, 115.44°E, which contains the highest energy potential. Financial analysis, with 25- year return period of investment and 3.60% interest rate, resulting levelized cost of energy (LCOE) of Rp 6,100.kWh-1. This value is higher than the national and regional selling nominal, in other word the energy cost of tidal stream turbine is relatively high in this location. Nearly 46% of energy cost is spent for turbine fabrication, and from the sensitivity analysis, cutting half the turbine costs may reduce the price by Rp 1,400.kWh-1 while increasing the amount of installed turbine is less significant. Despite of the high prices, the study shows that Toyapakeh Strait holds a promising resource of tidal stream energy. [ABSTRACT FROM AUTHOR]

Featured Application: This work outlines the opportunities for producing novel hybrid structures for marine energy systems by leveraging the benefits of combining additive and composite manufacturing techniques, and the potential this has for rapid prototyping. Many marine energy systems designers and developers are beginning to implement composite materials into the load-bearing structures of their devices, but traditional mold-making costs for composite prototyping are disproportionately high and lead times can be long. Furthermore, established molding techniques for marine energy structures generally require many manufacturing steps, such as secondary bonding and tooling. This research explores the possibilities of additively manufactured internal composite molds and how they can be used to reduce costs and lead times through novel design features and processes for marine energy composite structures. In this approach, not only can the composite mold be additively manufactured but it can also serve as part of the final load-bearing structure. We developed a conceptual design and implemented it to produce a reduced-scale additive/composite tidal turbine blade section to fully demonstrate the manufacturing possibilities. The manufacturing was successful and identified several critical features that could expedite the tidal turbine blade manufacturing process, such as single-piece construction, an integrated shear web, and embedded root fasteners. The hands-on manufacturing also helped identify key areas for continued research to allow for efficient, durable, and low-cost additive/composite-manufactured structures for future marine energy systems. [ABSTRACT FROM AUTHOR]

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With the rapid development of marine renewable energy technologies, the demand to mitigate the fluctuation of variable generators with energy storage technologies continues to increase. Offshore compressed air energy storage (OCAES) is a novel flexible-scale energy storage technology that is suitable for marine renewable energy storage in coastal cities, islands, offshore platforms, and offshore renewable energy farms. For deep-water applications, a marine riser is necessary for connecting floating platforms and subsea systems. Thus, the response characteristics of marine risers are of great importance for the stability and safety of the entire OCAES system. In this study, numerical models of two kinds of flexible risers, namely, catenary riser and lazy wave riser, are established in OrcaFlex software. The static and dynamic characteristics of the catenary and the lazy wave risers are analyzed under different environment conditions and internal pressure levels. A sensitivity analysis of the main parameters affecting the lazy wave riser is also conducted. Results show that the structure of the lazy wave riser is more complex than the catenary riser; nevertheless, the former presents better response performance. [ABSTRACT FROM AUTHOR]

Shao, M. and Wu, Z., 2019. China's renewable marine energy based on big data. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 597–600. Coconut Creek (Florida), ISSN 0749-0208. The China is located in the eastern part of the Asian continent and the western part of the Pacific Ocean, which is rich in renewable marine energy with various forms and the common characteristics of sustainability.The problem of environmental pollution is aggravated by the consumption of fossil energy, so people pay more and more attention to the development and utilization of renewable energy.The exploitation and utilization of Marine renewable energy is the inherent requirement of realizing the scientific development concept of our country and the inevitable choice of building an environment-friendly and resource-saving society in the 21st century.At present, all countries attach great importance to the development of marine energy and have formulated sound standards for marine energy development.The development of Marine energy can effectively alleviate the energy crisis and promote the innovation of marine energy technology industry.This paper expounds the current situation of Marine energy standardization and analyzes the specific problems and countermeasures according to the big data. [ABSTRACT FROM AUTHOR]

The China is located in the eastern part of the Asian continent and the western part of the Pacific Ocean, which is rich in renewable marine energy with various forms and the common characteristics of sustainability. The problem of environmental pollution is aggravated by the consumption of fossil energy, so people pay more and more attention to the development and utilization of renewable energy. The exploitation and utilization of Marine renewable energy is the inherent requirement of realizing the scientific development concept of our country and the inevitable choice of building an environment-friendly and resource-saving society in the 21st century. At present, all countries attach great importance to the development of marine energy and have formulated sound standards for marine energy development. The development of Marine energy can effectively alleviate the energy crisis and promote the innovation of marine energy technology industry. This paper expounds the current situation of Marine energy standardization and analyzes the specific problems and countermeasures according to the big data. [ABSTRACT FROM AUTHOR]

This paper focuses on connecting tidal turbine farms to the French electrical grid. One tidal farm is considered, which is the commercial farm. The connection state is defined by the active power and the voltage at the common coupling point (PCC, also called the delivery point), and is constrained to respect the grid code requirements. In order to ensure this connection, this paper develops an active power control framework constrained to the requirements of the grid code. This framework is based on the solution of a quadratic programming problem to meet the power demand at the PCC while respecting the requirements of the grid code in different plans. As the farm will be installed at the ocean depths, several kilometers of cables will be used to transport the electricity up to the PCC. Then, the power losses are also taken into account in this framework. This framework is applied to a commercial farm with realistic data to show its relevance and effectiveness. [ABSTRACT FROM AUTHOR]

ABSTRACT López-Gutiérrez, J.S.; Esteban, M.D., and Negro, V., 2018. Wave Energy Potential Assessment and Feasibility Analysis of Wave Energy Converters. Case Study: Spanish Coast. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp.1291–1295. Coconut Creek (Florida), ISSN 0749-0208. Wave energy is one of the marine renewable energy types, essential to achieve a sustainable development. Coastal countries need to know the wave energy potential along their coasts, so its contribution to the future electricity market is estimated. Spain has noticeable variations in its average wave climate, so it is essential to analyse numerous locations. For research purposes, wave energy potential is estimated based on data from the 15 Spanish State Port buoys currently in operation in deep waters. Because these buoys were set up at different times, with some moored around 2005, the sample between 2005 and 2015 is studied with the purpose of comparing results. REDEXT buoys, arranged from highest to lowest wave energy potential, are: Villano-Sisargas (56.84 kW/m), Cabo Silleiro (53.50 kW/m), Estaca de Bares (53.36 kW/m), Cabo de Peñas (39.66 kW/m), Bilbao-Vizcaya (39.09 kW/m), Gran Canaria (23.71 kW/m), Mahón (16.21 kW/m), Cabo de Begur (13.95 kW/m), Golfo de Cádiz (12.70 kW/m), Dragonera (10.16 kW/m), Cabo de Gata (8.43 kW/m), Cabo de Palos (8.17 kW/m), Tenerife Sur (6.93 kW/m), Tarragona (6.14 kW/m) and Valencia (5.42 kW/m). Some buoys were moored in the 1990s allowing an analysis to be made of how the average wave climate has changed over the last years. Furthermore, a study is undertaken analysing the feasibility of different wave energy converters, specifically Pelamis 750 kW, Oyster 300 kW, Aquabuoy 250 kW, and SSG 20,000 kW, in the 15 buoy locations. Energy production and the capacity factor of all devices for the 15 locations are calculated, obtaining as a result that the most suitable device for all the locations studied is Oyster, and the least suitable is SSG. All the results are shown in different comparative tables and figures, with a summary of the most emphasizing information in each buoy. [ABSTRACT FROM AUTHOR]

ABSTRACT Esteban, M.D.; López-Gutiérrez, J.S.; Negro, V; Laviña, M., and Muñoz-Sánchez, P., 2018. A New Classification of Wave Energy Converters Used for Selection of Devices. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1286–1290. Coconut Creek (Florida), ISSN 0749-0208. Wave is one of the marine renewable energy sources with the greatest potential. Currently, the technology is not completely prepared for a commercial development and its levelized cost of energy (LCOE) is still high. In fact, there are numerous types of wave energy converters (WECs) in the development phase. Given the differences between them, there are several classifications based on different aspects such as the location in relation to the distance to the coast and the bathymetry, the position relative to the sea level, the size and orientation, and the energy capture principle. However, none of the existing classifications considers the operating range at rated power according to the power matrix of the devices. This paper includes a new proposal for classification of WECs, named OPERAWEC (Operation Waver Energy Converters), with the aim of covering that gap. A methodology to implement the classification to different WECs is proposed, and that methodology is applied to ten different existing WECs (Wave Dragon, Pelamis, Aquabuoy, Archimedes Wave Swing, Oyster, Oceantec, OE Buoy, Pontoon, Seabed AB and Wavebob), classifying them into six different groups (Group I, Group II, Group III, Group IV, Group V and Group VI). Most of them belong to the Group IV and/or Group V, and some of them are categorised into several groups. The paper ends showing how to apply OPERAWEC classification as a part of a screening process for WECs selection in the Spanish Atlantic coast. Wave resource is assessed in two specific locations (Estaca de Bares and Golfo de Cádiz), considering four WECs (Pelamis, Aquabuoy, Archimedes Wave Swing, and Oyster). According OPERAWEC classification, Group II WECs for Estaca de Bares, and Group I and Group II WECs for Golfo de Cádiz are recommended. [ABSTRACT FROM AUTHOR]

In this paper we present a multi-sensor floating system designed to monitor marine energy parameters, in order to sample wind, wave, and marine current energy resources. For this purpose, a set of dedicated sensors to measure the height and period of the waves, wind, and marine current intensity and direction have been selected and installed in the system. The floating device incorporates wind and marine current turbines for renewable energy self-consumption and to carry out complementary studies on the stability of such a system. The feasibility, safety, sensor communications, and buoy stability of the floating device have been successfully checked in real operating conditions. [ABSTRACT FROM AUTHOR]

López-Gutiérrez, J.S.; Esteban, M.D., and Negro, V., 2018. Wave Energy Potential Assessment and Feasibility Analysis of Wave Energy Converters. Case Study: Spanish Coast. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp.1291–1295. Coconut Creek (Florida), ISSN 0749-0208. Wave energy is one of the marine renewable energy types, essential to achieve a sustainable development. Coastal countries need to know the wave energy potential along their coasts, so its contribution to the future electricity market is estimated. Spain has noticeable variations in its average wave climate, so it is essential to analyse numerous locations. For research purposes, wave energy potential is estimated based on data from the 15 Spanish State Port buoys currently in operation in deep waters. Because these buoys were set up at different times, with some moored around 2005, the sample between 2005 and 2015 is studied with the purpose of comparing results. REDEXT buoys, arranged from highest to lowest wave energy potential, are: Villano-Sisargas (56.84 kW/m), Cabo Silleiro (53.50 kW/m), Estaca de Bares (53.36 kW/m), Cabo de Peñas (39.66 kW/m), Bilbao-Vizcaya (39.09 kW/m), Gran Canaria (23.71 kW/m), Mahón (16.21 kW/m), Cabo de Begur (13.95 kW/m), Golfo de Cádiz (12.70 kW/m), Dragonera (10.16 kW/m), Cabo de Gata (8.43 kW/m), Cabo de Palos (8.17 kW/m), Tenerife Sur (6.93 kW/m), Tarragona (6.14 kW/m) and Valencia (5.42 kW/m). Some buoys were moored in the 1990s allowing an analysis to be made of how the average wave climate has changed over the last years. Furthermore, a study is undertaken analysing the feasibility of different wave energy converters, specifically Pelamis 750 kW, Oyster 300 kW, Aquabuoy 250 kW, and SSG 20,000 kW, in the 15 buoy locations. Energy production and the capacity factor of all devices for the 15 locations are calculated, obtaining as a result that the most suitable device for all the locations studied is Oyster, and the least suitable is SSG. All the results are shown in different comparative tables and figures, with a summary of the most emphasizing information in each buoy. [ABSTRACT FROM AUTHOR]

Esteban, M.D.; López-Gutiérrez, J.S.; Negro, V; Laviña, M., and Muñoz-Sánchez, P., 2018. A New Classification of Wave Energy Converters Used for Selection of Devices. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1286–1290. Coconut Creek (Florida), ISSN 0749-0208. Wave is one of the marine renewable energy sources with the greatest potential. Currently, the technology is not completely prepared for a commercial development and its levelized cost of energy (LCOE) is still high. In fact, there are numerous types of wave energy converters (WECs) in the development phase. Given the differences between them, there are several classifications based on different aspects such as the location in relation to the distance to the coast and the bathymetry, the position relative to the sea level, the size and orientation, and the energy capture principle. However, none of the existing classifications considers the operating range at rated power according to the power matrix of the devices. This paper includes a new proposal for classification of WECs, named OPERAWEC (Operation Waver Energy Converters), with the aim of covering that gap. A methodology to implement the classification to different WECs is proposed, and that methodology is applied to ten different existing WECs (Wave Dragon, Pelamis, Aquabuoy, Archimedes Wave Swing, Oyster, Oceantec, OE Buoy, Pontoon, Seabed AB and Wavebob), classifying them into six different groups (Group I, Group II, Group III, Group IV, Group V and Group VI). Most of them belong to the Group IV and/or Group V, and some of them are categorised into several groups. The paper ends showing how to apply OPERAWEC classification as a part of a screening process for WECs selection in the Spanish Atlantic coast. Wave resource is assessed in two specific locations (Estaca de Bares and Golfo de Cádiz), considering four WECs (Pelamis, Aquabuoy, Archimedes Wave Swing, and Oyster). According OPERAWEC classification, Group II WECs for Estaca de Bares, and Group I and Group II WECs for Golfo de Cádiz are recommended. [ABSTRACT FROM AUTHOR]

This paper presents a review of the main electrical components that are expected to be present in marine renewable energy arrays. The review is put in context by appraising the current needs of the industry and identifying the key components required in both device and array-scale developments. For each component, electrical, mechanical and cost considerations are discussed; with quantitative data collected during the review made freely available for use by the community via an open access online repository. This data collection updates previous research and addresses gaps specific to emerging offshore technologies, such as marine and floating wind, and provides a comprehensive resource for the techno-economic assessment of offshore energy arrays. [ABSTRACT FROM AUTHOR]

Multi-energy power systems can use energy generated from various sources to improve power generation reliability. This paper presents a cost-power generation model of a wind-tide-wave energy hybrid power system for use on a remote island, where the configuration is optimized using a genetic algorithm. A mixed integer programming model is used and a novel object function, including cost and power generation, is proposed to solve the boundary problem caused by existence of two goals. Using this model, the final optimized result is found to have a good fit with local resources. [ABSTRACT FROM AUTHOR]

There has been increased enthusiasm to mitigate the negative effects of fossil fuel consumption through the use of cleaner sources of energy, like marine renewable energy (MRE). Concerns about MRE deployments have motivated research on the ecological effects of these new man-made structures in marine environments. We assessed the extent to which soft-sediment habitats are influenced by the presence of artificial structures deployed in Yaquina Bay, Oregon, USA. Grain size analyses confirmed artificial structures altered the sediment distribution around them with larger grain sizes detected closer to the structures. Infaunal abundances were higher closer to the artificial structures; however, these differences did not result in statistically significant effects on diversity or richness in relation to distance from the structures, nor were they sufficient to cause statistically significant changes in infaunal communities as compared to reference areas. This study provided additional evidence that artificial structures alter their physical environment, but in our study detected differences were less than those observed between the two different regions of the estuary and any effects on infauna were localized and smaller than differences between different regions of the estuary. Conducting these studies in an Oregon estuary provided a good proxy for estimating potential effects of in-stream tidal energy deployments in the Pacific Northwest while also demonstrating the importance of site-specific research. [ABSTRACT FROM AUTHOR]

Tidal stream energy is a low-carbon energy source. Tidal stream turbines operate in a turbulent environment, and the effect of the structure between the turbine and seabed on this environment is not fully understood. An experimental study using 1:72 scale models based on a commercial turbine design was carried out to study the support structure influence on turbulent intensity around the turbine blades. The study was conducted using the wave-current tank at the Laboratory of Maritime Engineering (LABIMA), University of Florence. A realistic flow environment (ambient turbulent intensity = 11%) was established. Turbulent intensity was measured upstream and downstream of a turbine mounted on two different support structures (one resembling a commercial design, the other the same with an additional vertical element), in order to quantify any variation in turbulence and performance between the support structures. Turbine drive power was used to calculate power generation. Acoustic Doppler velocimetry (ADV) was used to record and calculate upstream and downstream turbulent intensity. In otherwise identical conditions, performance variation of only 4% was observed between two support structures. Turbulent intensity at 1, 3 and 5 blade diameters, both upstream and downstream, showed variation up to 21% between the two cases. The additional turbulent structures generated by the additional element of the second support structure appears to cause this effect, and the upstream propagation of turbulent intensity is believed to be permitted by surface waves. This result is significant for the prediction of turbine array performance. [ABSTRACT FROM AUTHOR]

The majority of WEC (wave energy converter) projects are expensive and pose a large risk to a developer. Currently no developers have been successful in commercialising a WEC. So far, many wave energy feasibility studies have only considered the LCOE (levelised cost of electricity), assessing investment in marine energy technologies from a purely financial point of view. No previous studies have, however, explicitly accounted for development risk as well as the LCOE to determine the feasibility of a project. This paper proposes a new methodology that can be used to account for both risk and the LCOE to give a clearer picture of the feasibility of a WEC development. By combining the LCOE and risk score for a particular development, the “value for risk” can be calculated, presented here as the “RR ratio” (“Risk/Reward ratio”). A number of case studies were chosen to test the model, investigating the RR ratio for a number of different WEC technologies and ranking them to suggest an optimal development path for the industry. Results showed that projects that combine many innovative technologies provide the best “value for risk”. These devices overall had the highest risk, suggesting that multiple developers are likely required to collaborate in order to reduce the risk down to acceptable levels for each. [ABSTRACT FROM AUTHOR]