bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of projected wave climate changes on the sizing and performance of OWCs: a focus on the Mediterranean and Atlantic European coastal waters
Authors: Simonetti Irene , Cappietti Lorenzo 
Published: September 2023

Reliable estimations of the Annual Energy Production (AEP) achievable with a certain Wave Energy Converter (WEC) are among the fundamental elements for a sound evaluation of the related Levelized Cost of Energy (LCOE) that plays a crucial role in the investment decision-making process. The lack of reliability in estimates of the device productivity can be a result of the uncertainty in the assessment of the available wave energy resource since the geometry of the device which maximizes the AEP is dependent on the specific wave climate at the foreseen installation site.
The Climate Data Store of the Copernicus Climate Change Service delivers projections of the wave climate along the 20 m bathymetric contours of the whole European coastlines, covering the period 2040-2100, under two Representative Concentration Pathway (RCP) scenarios (RCP4.5 and RCP8.5) [1].
This work addresses the effect of such long-term wave climate changes on the optimal sizing and performances of Oscillating Water Column (OWC) WECs to be installed along the Atlantic European coastline, expanding a previously published work in which the Mediterranean coastline was investigated [2]. The capture width of the OWC WEC under different wave conditions is computed using an empirical model [3] capable of predicting the device performance with acceptable accuracy and limited computational time.
The results show that the optimal geometry of the OWC WEC varies significantly in the different geographical locations, and that the long-term changes in the wave energy resource could cause a slight modification of the optimal geometry in each potential installation site. The AEP of the OWC WEC in the projected wave climate scenario can be significantly different compared to the present one, potentially contributing to reducing the LCOE of this wave energy conversion technology in some geographical locations.
REFERENCES:
[1] Caires, S., Yan, K., 2022. Ocean surface wave time series for the European coast from 1976 to 2100 derived from climate projections. (Accessed on Feb. 2022) DOI: 10.24381/cds.572bf382. Copernicus Climate Change Service (C3S) Climate Data Store (CDS)
[2] Simonetti, I., Cappietti, L., 2023, Mediterranean coastal wave-climate long-term trend in climate change scenarios and effects on the optimal sizing of OWC wave energy converters, Coastal Engineering, 173, 104247.
[3] Simonetti, I., Cappietti, L., Oumeraci, H., 2018. An empirical model as a supporting tool to optimize the main design parameters of a stationary oscillating water column wave energy converter. Appl. Energy 231, 1205–1215.
Integration of wave energy into Energy Systems: an insight to the system dynamics and ways forward
Authors: Lavidas George , Delgado Elizundia Felix , Blok Kornelis 
Published: September 2023

Wave energy is a rich and highly accessible renewable energy resource, that has largely been under-developed. Studies from the sector have tried to show the potential of benefits wave energy in “simple cases” or via small hybrid systems, the large scale incorporation of wave energy has not yet been fully investigated. Our approach uses a fully dynamic climate driven energy system model, which has undergone modifications to include wave energy converters and their associated dependencies.
This study explores the system dynamics and important elements that will be used for large scale wave energy integration; in a fully coupled European Energy System. We explore the cost pathways of different wave energy converters, the impact of climate data, and the impact of transmission capacity expansion under cost-optimal configurations of a multi-renewable European power system. From this preliminary approach we aim to provide the boundary conditions, and assumptions that will govern the integration of wave energy into the European Energy System up to 2050.
Wave Amplification inside an Open Circular Caisson for Wave Energy Conversion in Waters with Medium Energy Density
Authors: Chen Jiahn-Horng 
Published: September 2023

Wave energy is one of important marine renewable energy resources. Many studies have been devoted to harnessing the energy for human use. Though they are almost everywhere in the sea, waves can be much more significant in some sea areas than others. For example, the wave energy density in Asian waters is usually much less than that in European west coasts.
To make the wave energy harvesting more viable in Asian waters with medium wave energy density, we propose to employ an open caisson to amplify the wave locally and to combine it with a wave energy converter to tap the amplified wave energy. In this study, we focus on the effect of incident wave height on the amplification factor which is defined as the ratio of the wave height inside the caisson to that of the incident wave. Shown in Figure 1, the caisson is mounted vertically on the horizontal seabed in the open sea. At the edge of the opening, it has two guides on the two sides of the opening. They are identical in geometry and part of a solid cylinder. The purpose of the two guides is to enhance the wave amplification inside the caisson.
The study was conducted primarily by CFD computations and partially verified by experiments. In computations, the finite volume method was employed to discretize the Navier-Stokes equations. A multi-block grid was generated for computational purposes. The volume-of-fluid (VOF) method was used to capture the free surface. The nonlinear iterations were conducted with the PISO method. And the implicit time marching scheme was adopted in the time direction. It is interesting to find that the amplified wave height in the caisson is not linearly related to the incident wave height. Furthermore, the amplification factor is also a function of the incident wave period. The wave period at which the peak value of the amplification factor appears is insensitive to the wave height. The amplification factor is usually greater than unity for a wide range of incident wave period.
Evaluating the performance of turbulence closure models for tidal stream resource characterization
Authors: Yang Zhaoqing , Deb Mithun 
Published: September 2023

Harvesting tidal stream energy from the ocean for electricity generation has been considered as an energy resource alternative to fossil fuels for mitigating the negative impact of climate change and enhancing energy security and coastal resilience. Numerical models have been used extensively to characterize and assess tidal resources at potential tidal energy development sites. Turbulence plays an important role in site selection and tidal turbine farm deployment. However, most of the numerical modeling studies for tidal energy resource characterization do not include turbulence characteristics because of the limitation of Reynolds averaged Navier–Stokes coastal ocean model in resolving the inertial sub-range turbulence scales. However, studies also demonstrated that turbulence properties, such as turbulence intensity and turbulence kinetic energy, simulated by the coastal ocean models based on turbulence closures can be useful in assisting tidal resource characterization at tidal energy sites. In this study, we evaluated four General Ocean Turbulence Model (GOTM) turbulence closure models implemented in a tidal hydrodynamic model –Finite Volume Community Ocean Model (FVCOM) to characterize the tidal energy resource in the Western Passage, Maine, USA – a top ranked tidal energy site. The four turbulence closure models used in this analysis are k–kl (Mellor–Yamada Level 2.5), k-ε, k–ω, and a generic model. Model sensitivities showed that the MY2.5 model performed the best in comparison with the field measurements. In particular, the simulated time series of turbulence intensity and kinetic energy matched the observed data very well in the Western Passage. Detailed analysis was conducted to characterize turbulence properties on the horizontal plane and at selective cross-sections. This study demonstrated that turbulence properties simulated by a coastal ocean model, along with tidal hydrodynamic properties, can be very informative for tidal energy resource characterization and project site selection, as recommended by the International Electrotechnical Commission (IEC) technical specifications (IEC TS 62600-201).
Measurements of tidal flow variability in Ramsey Sound, Pembrokeshire
Authors: Miles Jon , Coles Daniel , Simmonds David , Paine Alex , Barr Sue 
Published: September 2023

The nature of the flow at in-stream tidal energy sites is particularly important for predicting array and device performance, and also for operations and maintenance planning. Previous developers have reported issues such as the choice of vessel, cost of operations, and the limits of operation of deployment vessels. The dynamics of the flow around slack water has been of particular interest at Ramsey Sound in Pembrokeshire (UK) for planning the recovery of an existing turbine, the Tidal Energy Limited ‘Deltastream’.
This research presents flow characteristics of Ramsey Sound, based on analysis of Acoustic Doppler Current Profiler (ADCP) measurements and tide gauge data from the nearby Standard Port of Milford Haven. The ADCP was located approximately 300 m across the channel, at the northern end of the channel, where the channel width was 1200 m and the mean depth was approximately 33 m. The flow dynamics were examined specifically to look at times potentially suitable for offshore operations Two weeks of data were used in the analysis, spanning a complete spring-neap cycle.
Results demonstrate that flow velocities exhibited clear asymmetry, with stronger flows on the northerly directed flood tide than on the ebb. There was considerable variation in the measured current speed around the time of the maximum, suggesting large scale bed feature generated turbulence. The flood (northerly) current maximum was approximately in phase with high water at Milford Haven. Cross correlation indicated that the flow generally led the elevation by 20 minutes. In contrast to the expected theory, the current strength at mid-depth was stronger than at the surface on the maximum flood tide. The maximum flow speed in the tide was reasonably predictable from the tide range at Milford. A threshold-based analysis of the ADCP measurements allowed the duration of slow-moving water to be identified for operation planning.
Operations and planning in light of sound understanding of hydrodynamics at tidal energy sites is critical for future economic success of the tidal energy sector. The results shown here from an ADCP deployment in Ramsey Sound have shown the capability to give useful tools for planning recovery operations.
Empowering Communities to Participate in Marine Energy Planning and Development
Authors: Chang Grace , Best Benjamin , Kramer Sharon 
Published: September 2023

To meet community priorities and equitable outcomes, marine renewable energy (MRE) projects, such as those for marine energy and offshore wind, require informed and collaborative marine spatial planning (MSP) to overcome significant cultural, societal, and economic barriers that may limit responsible and accelerated deployment. Effective MSP brings together coastal communities and ocean users to coordinate decision-making for sustainable use of marine resources. The goal of this project is to develop digital tools to enable easy access to information, interactive visualization tools, and feedback mechanisms to empower communities to engage in meaningful communications with other stakeholders in the MSP process.
In collaboration with community organization partners, the Santa Barbara Maritime Museum and Redwood Community Action Agency, we held community-based workshops to solicit needs for communities to gain knowledge and communicate concerns about MRE development. The key results from initial outreach activities are:

The MRE planning process must incorporate stakeholder feedback starting in its early stages (as early as siting). Community benefits must be clearly articulated and quantified.
Communities generally distrust offshore energy developers. Communication with regulators and developers together would be useful.
Community members are eager to learn about MRE. Their biggest knowledge gaps are MRE device and array characteristics (size, extent, location) and effects of MRE development on the viewshed, recreational activities, and on wildlife.
There is too much information available over disparate sources. Community members do not know where or how to search for answers to questions about MRE development in their communities (or elsewhere).
Community members want to hit the ‘Easy Button’. Data need to be digestible and tools need to be easy to use with little technical knowledge or experience necessary.

Outreach activities guided the development of the following digital tools:

Interactive infographics to communicate topics of concern (e.g., viewshed impacts and potential interactions with whales) in a visually engaging and interative platform.
News feed relevant to MRE to quickly digest headlines and read articles in greater detail, sort articles by topic, and react to articles or other comments.
Artificial intelligence (AI) driven chat bot, which uses the latest in AI, namely GPT-3 (Generative Pre-trained Transformer 3), to produce real-time answers to user questions. Answers are logged, and can be reviewed and revised by marine energy experts to provide human vetting of the results.
Commenting system to provide feedback on information throughout the site, as well as the tools themselves.

These tools will empower communities with information and feedback mechanisms to promote meaningful stakeholder engagement and communications, and therefore, informed decision-making. These tools represent a major leap forward in ocean multi-use management with MRE.
Tidal turbine wake characterization by vessel-mounted ADCP data analysis
Authors: Garcia Novo Patxi , Inubuse Masako , Terazaki Masakatsu , Matsuo Hiroshi , Archer Philip , Henzan Katsuhiro , Kyozuka Yusaku , Sakaguchi Daisaku 
Published: September 2023

Wakes generated downstream turbines are one of the key points to be considered for tidal stream energy farm layout design. Distance between consecutive turbines must be optimized considering available resource spatial distribution and the current velocity reduction caused by upstream turbines. Tidal turbine wake characteristics have been analyzed experimentally and numerically, however, there is still a lack of studies presenting data measured in the wake of large-size turbines in tidal sites.
In this paper, the wake generated downstream of a SIMEC Atlantis Energy 0.5 MW turbine in Naru Strait (Nagasaki Prefecture, Japan) is analyzed using data measured with a vessel-mounted ADCP. This analysis is based on the comparison between data measured before turbine installation (September 2020) and during turbine operation (March 2021, May 2021, and September 2021).
Due to the difficulties that measuring at the same position and the same tide moment with a vessel-mounted ADCP would mean, a direct comparison between these four datasets is unviable. To solve this issue, data were pretreated to calculate a ratio (RD) resulting from the division of current velocity values at every vertical layer by the current velocity measured at the shallowest layer. After that, this ratio is interpolated to a regular 3D mesh. Assuming that the current velocity profile shape for one point does not change with time, resulting RD values interpolated from data measured in different fieldworks can be compared.
The impact of tidal turbine operation on the current velocities is quantified with a variation ratio RV calculated by dividing RD during turbine operation (RD*) by RD before turbine installation (RD). These results show a clear velocity deficit even at 18D from the turbine, which clearly contrasts with results from other similar studies available in the literature, which may be related to the low turbulence intensity measured at the turbine installation point.
Validation of ERA5 Wave Energy Flux through Sailor diagram in Spain (2005-2014)
Authors: Saenz Jon , Carreno-Madinabeitia Sheila , Ibarra-Berastegi Gabriel , Ulazia Alain , Garro Mikel 
Published: September 2023

The aim of this study is to validate the ERA5 Wave Energy Flux (WEF) estimations against observational data. To that end, 0.5° x 0.5° resolution ERA5 reanalisis WEF values and corresponding data from 15 directional REDEXT buoys of Puertos del Estado surrounding the Iberian and Canary Islands’ coast covering a period of ten years (2005-2014) have been used.
In this study, the Sailor diagram and its methodology [1] have been used to compare the skill of the model for a two-dimensional variable (WEF). The methodology on which the Sailor diagram is built proposes a diagram along with different statistical indices. In this particular case, WEF is a vectorial magnitude, and its zonal and meridional components (WEFx and WEFy) have been assessed at the same time.
To compare the observed data with the ERA5 data, well-known indices extended to two dimensions such as RMSE, correlation and bias have been used, as well as variances of each component. Furthermore, to analyse if the WEFx and WEFy components of the ERA5 data are rotated in relation to the observations, their relative rotation angle, eccentricity, and congruence coefficient of the first EOF (Empirical Orthogonal Function) have also been examinated. This way, the analysis is extended to fully cover the dimensionality of the data.

[1] Sáenz J, Carreno-Madinabeitia S, Esnaola G, González-Rojí SJ, Ibarra-Berastegi G, Ulazia A. The Sailor diagram – A new diagram for the verification of two-dimensional vector data from multiple models. Geosci Model Dev. 2020;13(7):3221–40. https://doi.org/10.5194/gmd-13-3221-2020
Novel Hybrid Floating Breakwater- Wave Energy Converter Device: Preliminary Experimental Investigations
Authors: Russo Sara , Lugni Claudio , Contestabile Pasquale , Vicinanza Diego 
Published: September 2023

The marine space is increasingly gaining ground as the ideal candidate to drive the energy economic sector as it hosts a huge amount of natural resources to be exploited, such as waves, wind, and solar irradiation. Innovative devices harnessing these marine renewable resources have been thought to be assembled in a new concept of an energy hub for the Mediterranean Sea, recently proposed by the National Research Council of Italy.
The feasibility of this floating energy archipelago is strongly dependent on the creation of a protected sea area with reduced wave heights, where to safely install new types of floating devices for energy harvesting from the sea, like solar islands.
For this purpose, a floating breakwater module has been specifically designed to surround the archipelago with one or more rows. Moreover, investigating the possibility to implement a dual and alternative use of this floating module, as a traditional dissipative system and wave energy converter has resulted in an extremely challenging task. With respect to the existing hybrid floating breakwater-Wave Energy Converters in fact, the novelty of this device is the optimization of both functionalities by varying its draft.
In extremely rough seas, the hybrid module should only serve as a passive breakwater, soaking up incoming waves and safeguarding the equipment installed inside the archipelago. Otherwise, the floating module should operate as a WEC in more frequent mild sea states, assisting the archipelago's energy output. The whole produced energy can be stored and used to supply the development of new productive activities, such as aquaculture, the expensive process of seawater desalination, as well as the production of low environmental impact fuels like methanol or hydrogen.
The model's dual functionality is accomplished by different draft values. This parameter is directly influenced by the volume of water pumped into the module, which raises the floater's displacement. The module is almost completely immersed in the first scenario, which simulates breakwater functioning, increasing the device's stability and the amount of reflected and dissipated waves. On the other hand, when the module exhibits WEC behavior, a lower displacement is necessary, allowing greater device motions, able to better exploit the energy of the waves.
In this study, preliminary results obtained from an experimental campaign carried out on a 1:10 Froude-scaled model are reported. In particular, the dynamic behaviour of the hybrid device is evaluated in terms of response amplitude operators, while the attenuation performances are condensed in the transmission coefficient which indicates the reduction of the wave height inside the archipelago.
Designing Vortex Generators for Tidal Turbine Blades
Authors: Manolesos Marinos , Kaufmann Nicholas , Papadakis George 
Published: September 2023

Increasing tidal turbine performance through innovation is crucial if the cost of tidal energy is to become competitive compared to other sources of energy. The present investigation deals with the application of Vortex Generators (VGs) on tidal turbines in view of increasing their performance. The more mature wind energy industry uses passive VGs either as a retrofit or in the blade design process to reduce separation at the inboard part of wind turbine blades. Tidal turbine blades also experience flow separation and here we examine whether passive vane VGs can be used to reduce or suppress that separated flow.
Vortex generators (VGs) in various forms have been used and studied for flow separation control on wings since the 1940s [1]. Their working principle is relatively simple: they generate streamwise vortices that energise the boundary layer on the surface they are attached to, by bringing high momentum fluid closer to the surface [2]. This mechanism has been described by various researchers [3–6], while a number of studies have provided optimization guidelines under a variety of flow conditions [7–13].
In the present investigation, a VG configuration is selected following a thorough wind tunnel campaign. It is found that sizing parameters for the tidal turbine profile are very similar to the wind turbine relevant literature [13,14]. The best performing vane VG configuration had a height of 0.007c, which corresponded to half the local boundary layer height (0.5δ) for operational Reynolds numbers. The results are also used to validate a Reynolds Averaged Navier Stokes (RANS) VG modelling approach using the BAY model [15]. The validated method is used to simulate the flow past a tidal turbine in both model size (1:8) and full scale, see Figure 1. The results show that VGs do suppress flow separation in both cases. However, and importantly, it is revealed that the significance of rotational effects is such that when deciding VG placement locations, only the full size blade should be considered. In the interest of brevity, the performance increase caused by a standard VG configuration is show in Figure 2, where a power coefficient improvement of 1.05% is predicted at λ=3. Figure 3 shows the effect on the normal and tangential forces on the blade. In the final paper and presentation, the results for different VG locations will be included and analysed in detail.