Regulators involved in consenting/permitting marine renewable energy (MRE) have faced multiple challenges due to relatively new, unfamiliar technologies and uncertainty surrounding potential environmental impacts. This has resulted in slow progress for the MRE industry, including long consenting timeframes and extensive and expensive monitoring requirements, which increase financial risk for investors. OES-Environmental has surveyed regulators internationally to understand their key knowledge gaps and perspectives to support the development of the MRE industry. From the results of these surveys a data transferability process and a risk retirement pathway have been developed to assess consenting and monitoring requirements in proportion to risk. A tool for discovering existing data sets by using an online matrix has been developed, along with training materials, regulatory guidance documents, and a strategic outreach plan to engage regulators and advisers. his engagement and the application of these products should lead to a better understanding of the environmental effects of marine energy, and more efficient consenting processes.
{"title":"Engaging the Regulatory Community to Aid Environmental Consenting/Permitting Processes for Marine Renewable Energy","authors":"Deborah Rose, Mikaela Freeman, Andrea Copping","doi":"10.36688/imej.6.55-61","DOIUrl":"https://doi.org/10.36688/imej.6.55-61","url":null,"abstract":"Regulators involved in consenting/permitting marine renewable energy (MRE) have faced multiple challenges due to relatively new, unfamiliar technologies and uncertainty surrounding potential environmental impacts. This has resulted in slow progress for the MRE industry, including long consenting timeframes and extensive and expensive monitoring requirements, which increase financial risk for investors. OES-Environmental has surveyed regulators internationally to understand their key knowledge gaps and perspectives to support the development of the MRE industry. From the results of these surveys a data transferability process and a risk retirement pathway have been developed to assess consenting and monitoring requirements in proportion to risk. A tool for discovering existing data sets by using an online matrix has been developed, along with training materials, regulatory guidance documents, and a strategic outreach plan to engage regulators and advisers. his engagement and the application of these products should lead to a better understanding of the environmental effects of marine energy, and more efficient consenting processes.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138956148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonathan Whiting, Lysel Garavelli, Hayley Farr, Andrea Copping
The placement and operation of marine energy deployments in the ocean have the potential to change flow patterns, decrease wave heights, and/or remove energy from the oceanographic system. Changes in oceanographic systems resulting from harvesting marine energy, particularly tidal and wave energy, may be of concern. These changes include alterations in nearfield and farfield physical processes, as well as potential secondary environmental effects such as changes in sediment transport patterns, biological processes, or coastal erosion. Knowledge of changes in oceanographic systems associated with marine energy is primarily available from numerical modeling studies, informed by some laboratory tests and very few field measurements. A literature review was conducted using the Tethys knowledge base and other online sources, building on conclusions from the Ocean Energy Systems-Environmental State of the Science report. Potential changes in oceanographic systems that may be caused by marine energy differ between tidal and wave devices because of different extraction mechanisms and siting locations. Numerical models show that tidal extraction on the order of hundreds of megawatts or with significant channel blockage is required to create changes in oceanographic processes that exceed natural variability. Effects from wave energy extraction in arrays are localized and dependent on array spacing and proximity to the shore. Available evidence supports the conclusion that the risk of significant environmental effects from such changes could be retired (i.e., less investigation required for every project) for small deployments—those representative of the state of the industry in 2021. Determining changes in oceanographic systems to be low risk for small deployments can thereby streamline environmental consenting by reducing monitoring needs at this early stage in the industry.
{"title":"Effects of small marine energy deployments on oceanographic systems","authors":"Jonathan Whiting, Lysel Garavelli, Hayley Farr, Andrea Copping","doi":"10.36688/imej.6.45-54","DOIUrl":"https://doi.org/10.36688/imej.6.45-54","url":null,"abstract":"The placement and operation of marine energy deployments in the ocean have the potential to change flow patterns, decrease wave heights, and/or remove energy from the oceanographic system. Changes in oceanographic systems resulting from harvesting marine energy, particularly tidal and wave energy, may be of concern. These changes include alterations in nearfield and farfield physical processes, as well as potential secondary environmental effects such as changes in sediment transport patterns, biological processes, or coastal erosion. Knowledge of changes in oceanographic systems associated with marine energy is primarily available from numerical modeling studies, informed by some laboratory tests and very few field measurements. A literature review was conducted using the Tethys knowledge base and other online sources, building on conclusions from the Ocean Energy Systems-Environmental State of the Science report. Potential changes in oceanographic systems that may be caused by marine energy differ between tidal and wave devices because of different extraction mechanisms and siting locations. Numerical models show that tidal extraction on the order of hundreds of megawatts or with significant channel blockage is required to create changes in oceanographic processes that exceed natural variability. Effects from wave energy extraction in arrays are localized and dependent on array spacing and proximity to the shore. Available evidence supports the conclusion that the risk of significant environmental effects from such changes could be retired (i.e., less investigation required for every project) for small deployments—those representative of the state of the industry in 2021. Determining changes in oceanographic systems to be low risk for small deployments can thereby streamline environmental consenting by reducing monitoring needs at this early stage in the industry.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138956090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Araignous, Georges Safi, Y. Kervella, Nicolas Michelet, Neil Luxcey, Rui Duarte, Rocio Isorna, Vincenzo Nava
Designing reliable ocean energy devices with reduced costs is crucial for the sector’s development. This development of renewable energies should also be implemented in a sustainable manner and not cause additional environmental stress and related damage. In order for the ocean energy sector to consider environmental impacts at the earliest stage of concept creation, the Environmental and Social Acceptance (ESA) module was developed and included in an integrative suite of design and assessment tools (namely DTOceanPlus) to support technology innovation processes. Several complementary features were developed in the ESA module which provides insight into impacts at different levels. At local scale, environmental impacts are assessed in relation to the different design choices using thirteen functions (i.e. Footprint of the array, Collision risk with devices, Collision risk with operating vessels, Energy modification, Reef effect, Reserve effect, Resting place, Chemical pollution, Turbidity, Temperature modification, Electrical fields, Magnetic fields and Underwater noise) that cover various potential pressures induced by the ocean energy array. Moreover, surveys and mitigation measures are provided regarding endangered species potentially present. At global scale, a life cycle assessment is conducted to evaluate the carbon footprint of a project in terms of its contribution to global warming and the cumulative energy demand. Two reference models were used to exemplify the use and relevancy of the different features. Overall the ESA module provides insight and support to the ocean energy sector to achieve sustainable development of marine renewable energies.
{"title":"Environmental and Social Acceptance module: reducing global and local environmental impacts for Ocean Energy Projects","authors":"E. Araignous, Georges Safi, Y. Kervella, Nicolas Michelet, Neil Luxcey, Rui Duarte, Rocio Isorna, Vincenzo Nava","doi":"10.36688/imej.6.63-90","DOIUrl":"https://doi.org/10.36688/imej.6.63-90","url":null,"abstract":"Designing reliable ocean energy devices with reduced costs is crucial for the sector’s development. This development of renewable energies should also be implemented in a sustainable manner and not cause additional environmental stress and related damage. In order for the ocean energy sector to consider environmental impacts at the earliest stage of concept creation, the Environmental and Social Acceptance (ESA) module was developed and included in an integrative suite of design and assessment tools (namely DTOceanPlus) to support technology innovation processes. Several complementary features were developed in the ESA module which provides insight into impacts at different levels. At local scale, environmental impacts are assessed in relation to the different design choices using thirteen functions (i.e. Footprint of the array, Collision risk with devices, Collision risk with operating vessels, Energy modification, Reef effect, Reserve effect, Resting place, Chemical pollution, Turbidity, Temperature modification, Electrical fields, Magnetic fields and Underwater noise) that cover various potential pressures induced by the ocean energy array. Moreover, surveys and mitigation measures are provided regarding endangered species potentially present. At global scale, a life cycle assessment is conducted to evaluate the carbon footprint of a project in terms of its contribution to global warming and the cumulative energy demand. Two reference models were used to exemplify the use and relevancy of the different features. Overall the ESA module provides insight and support to the ocean energy sector to achieve sustainable development of marine renewable energies.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139170535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A linear potential flow model of a rotating lift-based wave energy converter is developed by assuming that the lift is generated by a pair of equal and opposite circulations and that the amplitude of motion is small. The linearisation of the hydrodynamics means that the forces can decomposed and expressions for the wave excitation force and radiation damping force are derived independently and shown to be related to each other through the Haskind Relations. The expressions for the forces are used to show that there is an optimum phase and product of circulation and radius of rotation to maximise the wave power extracted, which is equivalent to the optimum phase and amplitude of motion from ‘conventional’ wave energy converter theory. It is also shown that at this optimum condition 100% of the incident wave energy can be extracted. It is shown that the forces are directly proportional to the velocities due to the motion of the vortices, the water particle velocities due to the incident wave, and the water particle velocities induced by the vortices. The effect of the vortex-induced water particle velocities is considered and the importance of including these velocities on the passive generation of circulation, e.g. by hydrofoils, is highlighted. The impact of a sub-optimum product of circulation and radius of rotation is also investigated and shown that the power capture is not highly sensitive to the optimal conditions in the same way as ‘conventional’ wave energy converters
{"title":"Linear hydrodynamic model of rotating lift-based wave energy converters","authors":"Matt Folley, P. Lamont-Kane, Carwyn Frost","doi":"10.36688/imej.6.37-44","DOIUrl":"https://doi.org/10.36688/imej.6.37-44","url":null,"abstract":"A linear potential flow model of a rotating lift-based wave energy converter is developed by assuming that the lift is generated by a pair of equal and opposite circulations and that the amplitude of motion is small. The linearisation of the hydrodynamics means that the forces can decomposed and expressions for the wave excitation force and radiation damping force are derived independently and shown to be related to each other through the Haskind Relations. The expressions for the forces are used to show that there is an optimum phase and product of circulation and radius of rotation to maximise the wave power extracted, which is equivalent to the optimum phase and amplitude of motion from ‘conventional’ wave energy converter theory. It is also shown that at this optimum condition 100% of the incident wave energy can be extracted. It is shown that the forces are directly proportional to the velocities due to the motion of the vortices, the water particle velocities due to the incident wave, and the water particle velocities induced by the vortices. The effect of the vortex-induced water particle velocities is considered and the importance of including these velocities on the passive generation of circulation, e.g. by hydrofoils, is highlighted. The impact of a sub-optimum product of circulation and radius of rotation is also investigated and shown that the power capture is not highly sensitive to the optimal conditions in the same way as ‘conventional’ wave energy converters","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138955479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The potential wave power has been assessed based on long-term wave data along a marginal sea area offshore Phu Yen province in Central Vietnam. Based on the publicly available WaveWatch-III reanalysis wave data (NOAA), the deep-water wave climate during the period from 1989 to 2019 has been analysed and used as the boundary condition for the MIKE21 spectral wave model. The hydrodynamic module of MIKE21 is also run in coupled mode. The model has been calibrated and verified against the measured data at three wave gauges. Simulation has been performed for every month, each with 1-2 typical wave conditions. The results show that the highest wave power (~29 kW/m) occurs in December. The distribution of wave power along the 30-m depth contour has also been presented for the annual average, NE monsoon (winter) average, and S monsoon (summer) average. The distribution map shows that wave power is slightly higher in the south of this area, and the NE monsoon season comes along with much higher wave power (7.4 times compared to that of the S monsoon season). These findings may aid in planning effective exploitation of wave energy for the region.
{"title":"Assessment of potential wave power along a coastal province, Central Vietnam","authors":"T. T. Tung, N. Q. Chien","doi":"10.36688/imej.6.27-35","DOIUrl":"https://doi.org/10.36688/imej.6.27-35","url":null,"abstract":"The potential wave power has been assessed based on long-term wave data along a marginal sea area offshore Phu Yen province in Central Vietnam. Based on the publicly available WaveWatch-III reanalysis wave data (NOAA), the deep-water wave climate during the period from 1989 to 2019 has been analysed and used as the boundary condition for the MIKE21 spectral wave model. The hydrodynamic module of MIKE21 is also run in coupled mode. The model has been calibrated and verified against the measured data at three wave gauges. Simulation has been performed for every month, each with 1-2 typical wave conditions. The results show that the highest wave power (~29 kW/m) occurs in December. The distribution of wave power along the 30-m depth contour has also been presented for the annual average, NE monsoon (winter) average, and S monsoon (summer) average. The distribution map shows that wave power is slightly higher in the south of this area, and the NE monsoon season comes along with much higher wave power (7.4 times compared to that of the S monsoon season). These findings may aid in planning effective exploitation of wave energy for the region.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42638892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wave energy is a kind of clean renewable energy that is huge and still need further research. Point absorber wave energy converter (PA-WEC) is widely utilized for offshore power devices. The PA-WEC utilizes the heave motion to drive linear electric generator or a hydraulic motor to generator using power take off (PTO) system. And the PTO system usually is assumed to be a linear spring and a linear damper. Because of the larger motion, the PTO system, which exhibited non-linear behavior, is considered as linear spring with the nonlinear hardening spring and a linear damper. Through the time domain method, the dynamic model of the PA-WEC is developed under irregular waves. The state space model replaced the convolution term in the frequency domain equation. The dynamic response of the PA-WEC is researched considering different environmental parameters by Runge-Kutta method. Then the power and power ratio performance of the system is obtained. Compare with the linear WEC, the results show that the nonlinear WEC can increase the power captured in irregular waves.
{"title":"Dynamic performance of a point absorber WEC considering nonlinear hardening spring under irregular waves","authors":"Z. Chang, Z. Hou, Zhongqiang Zheng","doi":"10.36688/imej.6.19-25","DOIUrl":"https://doi.org/10.36688/imej.6.19-25","url":null,"abstract":"Wave energy is a kind of clean renewable energy that is huge and still need further research. Point absorber wave energy converter (PA-WEC) is widely utilized for offshore power devices. The PA-WEC utilizes the heave motion to drive linear electric generator or a hydraulic motor to generator using power take off (PTO) system. And the PTO system usually is assumed to be a linear spring and a linear damper. Because of the larger motion, the PTO system, which exhibited non-linear behavior, is considered as linear spring with the nonlinear hardening spring and a linear damper. Through the time domain method, the dynamic model of the PA-WEC is developed under irregular waves. The state space model replaced the convolution term in the frequency domain equation. The dynamic response of the PA-WEC is researched considering different environmental parameters by Runge-Kutta method. Then the power and power ratio performance of the system is obtained. Compare with the linear WEC, the results show that the nonlinear WEC can increase the power captured in irregular waves.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47121300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The low-RPM Torque Converter (LRTC) is a rotating generator concept for use on the seabed with the driving force from sea waves motion on the sea surface. This concept is built up of two identical generators connected opposite each other via a spring drum with a built-in ball bearing clutch. The drum is connected to a buoy on the sea surface via a wire, the wire is rolled around the spring drum. With sea waves, the buoy moves either upwards or downwards and pulls the wire upwards or downwards. This movement causes the generators to spin. This article presents an upgrade of the LRTC generator concept and upgraded measurement system, both hardware and software. A flywheel system of the thin-disc type has been designed for direct connection to the generator's rotor shaft and an electronic measuring system has also been developed for more accurate measurements and minor disturbances. More detailed tests have been performed both for the purpose of comparing the systems and to explore the performance of the generator concept in more detail. Three different experiments have been done in this article. The first two experiments were performed to investigate the performance of the flywheel and to see the performance of the LRTC system with and without flywheel. The third experiment investigated the optimization of the flywheel mass by increasing the mass of the flywheel with the addition of more thin discs. All movements are simulated with a six-joint industrial robot. Several sinusoidal types of wave motions have been simulated with different time periods and also several real wave climate motions (data taken from fields) have been simulated with the robot. The experiments show that the addition of the flywheel in the LRTC system provides advantages in increasing both peak power, average output power and also softens the output power oscillation.
{"title":"Low-RPM torque converter (LRTC) with Integrated direct shaft flywheel","authors":"Dana Salar, Erik Hultman, A. Savin","doi":"10.36688/imej.6.1-10","DOIUrl":"https://doi.org/10.36688/imej.6.1-10","url":null,"abstract":"The low-RPM Torque Converter (LRTC) is a rotating generator concept for use on the seabed with the driving force from sea waves motion on the sea surface. This concept is built up of two identical generators connected opposite each other via a spring drum with a built-in ball bearing clutch. The drum is connected to a buoy on the sea surface via a wire, the wire is rolled around the spring drum. With sea waves, the buoy moves either upwards or downwards and pulls the wire upwards or downwards. This movement causes the generators to spin. \u0000This article presents an upgrade of the LRTC generator concept and upgraded measurement system, both hardware and software. \u0000A flywheel system of the thin-disc type has been designed for direct connection to the generator's rotor shaft and an electronic measuring system has also been developed for more accurate measurements and minor disturbances. \u0000More detailed tests have been performed both for the purpose of comparing the systems and to explore the performance of the generator concept in more detail. \u0000Three different experiments have been done in this article. The first two experiments were performed to investigate the performance of the flywheel and to see the performance of the LRTC system with and without flywheel. \u0000The third experiment investigated the optimization of the flywheel mass by increasing the mass of the flywheel with the addition of more thin discs. \u0000All movements are simulated with a six-joint industrial robot. Several sinusoidal types of wave motions have been simulated with different time periods and also several real wave climate motions (data taken from fields) have been simulated with the robot. The experiments show that the addition of the flywheel in the LRTC system provides advantages in increasing both peak power, average output power and also softens the output power oscillation.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49333047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
James Slingsby, B. Scott, L. Kregting, J. Mcilvenny, Jared Wilson, Marion Yanez, B. Williamson
Unmanned Aerial Vehicles (UAVs), or drones, offer the ability to collect cost-effective fine-scale imagery that is suitable for the capture of concurrent hydrodynamic and faunal data within tidal stream environments. This is a necessary stage of information gathering to inform tidal energy device design, advise control and maintenance strategies and better inform environmental consenting processes. For this study a total of sixty-three UAV surveys were undertaken within the Inner Sound of the Pentland Firth, Scotland, UK, over two 4-day periods in 2016 and 2018. The aims of this data collection effort were to characterise bathymetrically driven hydrodynamic features, comprising of kolk-boil distribution, presence, and area, as well as marine life such as seabird distributions, presence, and orientation relative to the flow. To achieve this, a method to extract quantifiable metrics from UAV imagery was required. This paper details the processes and methodology to create a graphical user interface (GUI) to provide these outputs rather than examining specific results. It includes an explanation of the criteria that the GUI needed to meet to be able to process the imagery, a description of the workflow and an explanation of the sub-routines required such as image registration and calibration. The outputs of the GUI, and their relevance to tidal energy developments, are also discussed. Finally, this paper details future work incorporating computer vision techniques to improve the accuracy, reliability, and processing speed of the GUI.
{"title":"The bigger picture: developing a low-cost graphical user interface to process drone imagery of tidal stream environments","authors":"James Slingsby, B. Scott, L. Kregting, J. Mcilvenny, Jared Wilson, Marion Yanez, B. Williamson","doi":"10.36688/imej.6.11-17","DOIUrl":"https://doi.org/10.36688/imej.6.11-17","url":null,"abstract":"Unmanned Aerial Vehicles (UAVs), or drones, offer the ability to collect cost-effective fine-scale imagery that is suitable for the capture of concurrent hydrodynamic and faunal data within tidal stream environments. This is a necessary stage of information gathering to inform tidal energy device design, advise control and maintenance strategies and better inform environmental consenting processes. For this study a total of sixty-three UAV surveys were undertaken within the Inner Sound of the Pentland Firth, Scotland, UK, over two 4-day periods in 2016 and 2018. The aims of this data collection effort were to characterise bathymetrically driven hydrodynamic features, comprising of kolk-boil distribution, presence, and area, as well as marine life such as seabird distributions, presence, and orientation relative to the flow. To achieve this, a method to extract quantifiable metrics from UAV imagery was required. This paper details the processes and methodology to create a graphical user interface (GUI) to provide these outputs rather than examining specific results. It includes an explanation of the criteria that the GUI needed to meet to be able to process the imagery, a description of the workflow and an explanation of the sub-routines required such as image registration and calibration. The outputs of the GUI, and their relevance to tidal energy developments, are also discussed. Finally, this paper details future work incorporating computer vision techniques to improve the accuracy, reliability, and processing speed of the GUI. \u0000 \u0000 \u0000 ","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45483866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-fidelity simulations using computational fluid dynamics (CFD) for wave-body interaction are becoming increasingly common and important for wave energy converter (WEC) design. The open source finite volume toolbox OpenFOAM is one of the most frequently used platforms for wave energy. There are currently two ways to account for moving bodies in OpenFOAM: (i) mesh morphing, where the mesh deforms around the body; and (ii) an overset mesh method where a separate body mesh moves on top of a background mesh. Mesh morphing is computationally efficient but may introduce highly deformed cells for combinations of large translational and rotational motions. The overset method allows for arbitrarily large body motions and retains the quality of the mesh. However, it comes with a substantial increase in computational cost and possible loss of energy conservation due to the interpolation. In this paper we present a straightforward extension of the spherical linear interpolation (SLERP) based mesh morphing algorithm that increase the stability range of the method. The mesh deformation is allowed to be interpolated independently for different modes of motion, which facilitates tailored mesh motion simulations. The paper details the implementation of the method and evaluates its performance with computational examples of a cylinder with a moonpool. The examples show that the modified mesh morphing approach handles large motions well and provides a cost effective alternative to overset mesh for survival conditions.
{"title":"Facilitating Large-Amplitude Motions of Wave Energy Converters in OpenFOAM by a modified Mesh Morphing Approach","authors":"Johannes Palm, C. Eskilsson","doi":"10.36688/imej.5.257-264","DOIUrl":"https://doi.org/10.36688/imej.5.257-264","url":null,"abstract":"High-fidelity simulations using computational fluid dynamics (CFD) for wave-body interaction are becoming increasingly common and important for wave energy converter (WEC) design. The open source finite volume toolbox OpenFOAM is one of the most frequently used platforms for wave energy. There are currently two ways to account for moving bodies in OpenFOAM: (i) mesh morphing, where the mesh deforms around the body; and (ii) an overset mesh method where a separate body mesh moves on top of a background mesh. Mesh morphing is computationally efficient but may introduce highly deformed cells for combinations of large translational and rotational motions. The overset method allows for arbitrarily large body motions and retains the quality of the mesh. However, it comes with a substantial increase in computational cost and possible loss of energy conservation due to the interpolation. In this paper we present a straightforward extension of the spherical linear interpolation (SLERP) based mesh morphing algorithm that increase the stability range of the method. The mesh deformation is allowed to be interpolated independently for different modes of motion, which facilitates tailored mesh motion simulations. The paper details the implementation of the method and evaluates its performance with computational examples of a cylinder with a moonpool. The examples show that the modified mesh morphing approach handles large motions well and provides a cost effective alternative to overset mesh for survival conditions.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42153104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Renewable energy allows electricity generation with lower environmental and resource impact than generation from fossil fuels. However, the manufacture, use and ultimate disposal of the equipment used to capture this energy has an environmental impact, which should be minimised. Tidal turbine blades are currently primarily manufactured from glass-fibre reinforced polymers. Such blades cannot be recycled at the end of their life, and are disposed of in landfill or by incineration. As the tidal energy industry grows, the volume of non-recyclable waste is a potential problem. Here we consider the environmental impact of ten combinations of material and disposal method for tidal stream turbine blades, including recyclable options. Our findings suggest that glass fibre blades have greenhouse gas emissions of around 15,500 kgCO2e for the scope considered, and a significant environmental impact in all impact categories, which would be increased by changing to carbon fibre (99% mean increase from glass fibre across impact categories) or steel (134% mean increase from glass fibre across impact categories) blades, but that composite materials using flax fibre and recyclable resin may have lower impact (26% mean decrease from glass fibre across impact categories), provided they are treated correctly after use. These materials may also offer the potential for lower cost blades in future.
{"title":"Comparative Life Cycle Assessment of tidal stream turbine blades","authors":"S. R. Walker, P. Thies, L. Johanning","doi":"10.36688/imej.5.249-256","DOIUrl":"https://doi.org/10.36688/imej.5.249-256","url":null,"abstract":"Renewable energy allows electricity generation with lower environmental and resource impact than generation from fossil fuels. However, the manufacture, use and ultimate disposal of the equipment used to capture this energy has an environmental impact, which should be minimised. Tidal turbine blades are currently primarily manufactured from glass-fibre reinforced polymers. Such blades cannot be recycled at the end of their life, and are disposed of in landfill or by incineration. As the tidal energy industry grows, the volume of non-recyclable waste is a potential problem. Here we consider the environmental impact of ten combinations of material and disposal method for tidal stream turbine blades, including recyclable options. Our findings suggest that glass fibre blades have greenhouse gas emissions of around 15,500 kgCO2e for the scope considered, and a significant environmental impact in all impact categories, which would be increased by changing to carbon fibre (99% mean increase from glass fibre across impact categories) or steel (134% mean increase from glass fibre across impact categories) blades, but that composite materials using flax fibre and recyclable resin may have lower impact (26% mean decrease from glass fibre across impact categories), provided they are treated correctly after use. These materials may also offer the potential for lower cost blades in future.","PeriodicalId":36111,"journal":{"name":"International Marine Energy Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45443190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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