David Ogden, Bharath Aidan, Wanan Sheng, George Aggidis
In this study, we present the development of a numerical model of the TALOS Wave Energy Converter (WEC) in WEC-Sim and compare it with existing numerical in-house models from Lancaster and results from DNV's Sesam code. The objective of this work is to validate the performance of the TALOS WEC using WEC-Sim and compare the results with those obtained from other numerical models. The TALOS WEC is a promising technology for the generation of clean, renewable energy from ocean waves. The development of a reliable numerical model for the TALOS WEC is crucial for its design and optimization. To achieve this, we have implemented the TALOS WEC in WEC-Sim and compared the results to in-house models from Lancaster and to results from DNV's Sesam code. Our results show good agreement with the results from Lancaster and DNV, demonstrating the accuracy and reliability of the numerical model developed in WEC-Sim. This work advances the field of wave energy conversion by providing a verified numerical model of the TALOS WEC, which can be used for further optimization and design studies.
{"title":"Comparing Numerical Models of the TALOS Wave Energy Converter","authors":"David Ogden, Bharath Aidan, Wanan Sheng, George Aggidis","doi":"10.36688/ewtec-2023-532","DOIUrl":"https://doi.org/10.36688/ewtec-2023-532","url":null,"abstract":"In this study, we present the development of a numerical model of the TALOS Wave Energy Converter (WEC) in WEC-Sim and compare it with existing numerical in-house models from Lancaster and results from DNV's Sesam code. The objective of this work is to validate the performance of the TALOS WEC using WEC-Sim and compare the results with those obtained from other numerical models. The TALOS WEC is a promising technology for the generation of clean, renewable energy from ocean waves. The development of a reliable numerical model for the TALOS WEC is crucial for its design and optimization. To achieve this, we have implemented the TALOS WEC in WEC-Sim and compared the results to in-house models from Lancaster and to results from DNV's Sesam code. Our results show good agreement with the results from Lancaster and DNV, demonstrating the accuracy and reliability of the numerical model developed in WEC-Sim. This work advances the field of wave energy conversion by providing a verified numerical model of the TALOS WEC, which can be used for further optimization and design studies.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127551239","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}
John Ashlin Samuel, V. Venugopal, Christopher Retzler, Qingwei Ma
The design of moored floating wave energy converters (WECs) must take into account extreme responses and mooring line loads in order to ensure their survival and continued wave power generation in the ocean environment. This study focuses on Mocean Energy's hinged raft WEC and aims to provide a comprehensive understanding of its hydrodynamic characteristics in survival wave conditions. To achieve this, a physical model study was conducted on a Froude scale of 1 in 50 at the FloWave Ocean Energy Research Facility, University of Edinburgh. The experiments involved the use of NewWaves focusing of crest and trough at the model hinge location, as well as long irregular waves. Motion responses of the fore and aft bodies of the WEC were measured using a Qualisys camera, and single component load cells were used to measure the forces in the 3-point catenary mooring line. The hydrodynamic characteristics of the WEC were evaluated in terms of response amplitude operators and non-dimensional mooring line loads. Results indicate that the fore and aft bodies of the WEC exhibit similar motion responses, except for the pitch motion. The aft body has a pitch response 2 to 3 times higher than the fore body. Concerning the moorings, the wave load on the mooring line in line with the wave direction was found to be higher than the other two mooring lines which were arranged at an angle to the wave direction. In this paper, a brief discussion of the model set-up, parameters, test procedure, analysis of results, and discussion will be reported. The results will provide insight into the behaviour of the Mocean device in survival wave conditions and will aid with the determination of appropriate design parameters for optimal performance and survival in the ocean environment.
{"title":"Hydrodynamic Response of Mocean Wave Energy Converter in Extreme Waves","authors":"John Ashlin Samuel, V. Venugopal, Christopher Retzler, Qingwei Ma","doi":"10.36688/ewtec-2023-582","DOIUrl":"https://doi.org/10.36688/ewtec-2023-582","url":null,"abstract":"The design of moored floating wave energy converters (WECs) must take into account extreme responses and mooring line loads in order to ensure their survival and continued wave power generation in the ocean environment. This study focuses on Mocean Energy's hinged raft WEC and aims to provide a comprehensive understanding of its hydrodynamic characteristics in survival wave conditions. To achieve this, a physical model study was conducted on a Froude scale of 1 in 50 at the FloWave Ocean Energy Research Facility, University of Edinburgh. \u0000The experiments involved the use of NewWaves focusing of crest and trough at the model hinge location, as well as long irregular waves. Motion responses of the fore and aft bodies of the WEC were measured using a Qualisys camera, and single component load cells were used to measure the forces in the 3-point catenary mooring line. The hydrodynamic characteristics of the WEC were evaluated in terms of response amplitude operators and non-dimensional mooring line loads. \u0000Results indicate that the fore and aft bodies of the WEC exhibit similar motion responses, except for the pitch motion. The aft body has a pitch response 2 to 3 times higher than the fore body. Concerning the moorings, the wave load on the mooring line in line with the wave direction was found to be higher than the other two mooring lines which were arranged at an angle to the wave direction. \u0000In this paper, a brief discussion of the model set-up, parameters, test procedure, analysis of results, and discussion will be reported. The results will provide insight into the behaviour of the Mocean device in survival wave conditions and will aid with the determination of appropriate design parameters for optimal performance and survival in the ocean environment.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129142405","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}
Reflecting in the acceleration of the changes in ecological, climatological and generally planetary health, it is critical to employ those energy source as well and those energy used that are of the highest ratio of benefit to effort and deliver the most valuable and impactful, tangible contribution in service of natural commons and common societal good. Such considerations hold for all ocean energy types and especially for ocean wave energy. Thus, it is not only important to consider the resource that is converted into the standard form of usable energy, that is, in the form of electricity and to deliver to the most prominent marketplace, that is, the continental grid; it is equally important to consider the use, purpose and impact after converted energy. Reflecting on the entire value chain from marine renewable energy to a) usable energy to b) the actual use and purpose of the energy may lead to highly impactful implementations with more direct delivery of the renewable energy to the valued application. In such more direct paths from resource to impact the extracted energy and the applied energy is a mean to the purpose rather than a means to an end. Assessments of marine renewable energy markets other than powering the continental grid, such as Powering the Blue Economy, have been investigated and numerous research efforts are underway. However, to fully maximize the achievable impact of ocean wave energy it is critical to extend the consideration from replacing the energy source in existing applications to the enablement of highly impactful applications that are currently not existing or are not operated at the magnitude when powered by ocean waves. Highest effectiveness is achieved when the uniqueness of the renewable energy form matches the unique needs of the targeted application. For ocean wave energy the uniqueness lies in relative consistency, high degree of forecastability, energy density and the ubiquitous nature across the oceans. These provide a plethora of opportunities to serve markets and purposes that are directly in or based on the oceans. Technology development progress indicators such as Technology Readiness Levels (TRL) and Technology Performance Levels (TPL) are typically used to span up the technology development space and provide a framework and orientation for the desired technology development trajectories. Based on the description of the motivations above the paper and presentation with introduce and describe additional and alternative technology development indicators that directly point and guide the development towards impactful application and purpose as the desired technology development goal. In order to provide a clear understanding of impact markets and the associated values, thus, their specific currency these are best served in, three impact markets are presented in detail as concrete examples. These support planetary and ocean health in different ways through carbon capture, acceleration of the depl
{"title":"Ocean Energy: Markets – Currency – Impact. Dimension of & Choices in the Technology Development Space","authors":"Jochem Weber","doi":"10.36688/ewtec-2023-507","DOIUrl":"https://doi.org/10.36688/ewtec-2023-507","url":null,"abstract":"Reflecting in the acceleration of the changes in ecological, climatological and generally planetary health, it is critical to employ those energy source as well and those energy used that are of the highest ratio of benefit to effort and deliver the most valuable and impactful, tangible contribution in service of natural commons and common societal good. Such considerations hold for all ocean energy types and especially for ocean wave energy. \u0000Thus, it is not only important to consider the resource that is converted into the standard form of usable energy, that is, in the form of electricity and to deliver to the most prominent marketplace, that is, the continental grid; it is equally important to consider the use, purpose and impact after converted energy. \u0000Reflecting on the entire value chain from marine renewable energy to a) usable energy to b) the actual use and purpose of the energy may lead to highly impactful implementations with more direct delivery of the renewable energy to the valued application. In such more direct paths from resource to impact the extracted energy and the applied energy is a mean to the purpose rather than a means to an end. \u0000Assessments of marine renewable energy markets other than powering the continental grid, such as Powering the Blue Economy, have been investigated and numerous research efforts are underway. However, to fully maximize the achievable impact of ocean wave energy it is critical to extend the consideration from replacing the energy source in existing applications to the enablement of highly impactful applications that are currently not existing or are not operated at the magnitude when powered by ocean waves. \u0000Highest effectiveness is achieved when the uniqueness of the renewable energy form matches the unique needs of the targeted application. For ocean wave energy the uniqueness lies in relative consistency, high degree of forecastability, energy density and the ubiquitous nature across the oceans. These provide a plethora of opportunities to serve markets and purposes that are directly in or based on the oceans. \u0000Technology development progress indicators such as Technology Readiness Levels (TRL) and Technology Performance Levels (TPL) are typically used to span up the technology development space and provide a framework and orientation for the desired technology development trajectories. Based on the description of the motivations above the paper and presentation with introduce and describe additional and alternative technology development indicators that directly point and guide the development towards impactful application and purpose as the desired technology development goal. \u0000In order to provide a clear understanding of impact markets and the associated values, thus, their specific currency these are best served in, three impact markets are presented in detail as concrete examples. These support planetary and ocean health in different ways through carbon capture, acceleration of the depl","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126715938","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}
Power take off in a wave energy converter has a number of unique requirements. It must convert low speed oscillating motion into electricity in a reliable, low maintenance manner. A direct drive system, where the electrical machine is optimised to operate at low speed, has the potential to offer a mechanically robust and simple solution. Similar to a hydraulic power take off, the only regular maintenance would be to inspect and replace the seal between moving parts. One strategy for removing regular maintenance is to have an unsealed system, i.e. one where sea water is allowed throughout the electrical machine. A fully flooded electrical machine has benefits in terms of cooling, but poses challenges relating to reliability, corrosion, biofouling and lubrication. Biofilm refers to a thin layer of fouling organisms which can interfere with the operation of components. Recent work has found that submerged surfaces can be kept free of biofouling using projected ultraviolet (UV) light from LEDs. This paper discusses the testing procedure and impact of the UVC irradiation on biofilm prevention within the active part of an electric generator in a systematic manner, with a view to accelerate its translation to full-scale applications. A prototype generator is being developed which will be installed in the North Sea, consisting of a submerged linear tubular electrical machine. A magnetic tubular translator will oscillate within a cylinder that houses stator coils. Lubrication will be by way of solid polymer bearings. In order that the active part of the electrical machine can oscillate smoothly, it is imperative that biofilm is prevented from colonising on the bearing surface, which also makes up the magnetic gap of the electrical machine. The system will have a slow reciprocating oscillation, with a peak speed of perhaps 2m/s. For most wave energy converters there will be brief static periods twice in every wave, and in calm seas these could be prolonged to several hours or even days. In low energy sea states oscillation amplitude could be less than the fully rated amplitude, meaning different parts of the bearing surface could be exposed for different amounts of time. Early-stage work is underway to investigate the use of UV irradiation in the active part of the electrical machine and bearing surface as biofilm prevention. Flat panels (600mm x 220mm) are used to simulate the original surfaces between moving parts. To achieve biofilm growth, an artificial slime farm was deployed which allows test panels to be subjected to a continuous dynamic flow. The light source of UV irradiation was provided by Light Emitting Diodes (LEDs) with 278nm wavelength. The effectiveness of the biofilm prevention by UVC were evaluated by Image Analysis The results indicate that UVC can significantly control biofilm presence on the panels. It also has demonstrated that intermittent UV can achieve successful biofilm prevention on submerged surfaces. However, observations
{"title":"Biofilm prevention in the generator of a direct drive wave energy converter","authors":"Nick Baker, Serkan Turkmen, Chang Li","doi":"10.36688/ewtec-2023-270","DOIUrl":"https://doi.org/10.36688/ewtec-2023-270","url":null,"abstract":"Power take off in a wave energy converter has a number of unique requirements. It must convert low speed oscillating motion into electricity in a reliable, low maintenance manner. A direct drive system, where the electrical machine is optimised to operate at low speed, has the potential to offer a mechanically robust and simple solution. Similar to a hydraulic power take off, the only regular maintenance would be to inspect and replace the seal between moving parts. One strategy for removing regular maintenance is to have an unsealed system, i.e. one where sea water is allowed throughout the electrical machine. A fully flooded electrical machine has benefits in terms of cooling, but poses challenges relating to reliability, corrosion, biofouling and lubrication. \u0000Biofilm refers to a thin layer of fouling organisms which can interfere with the operation of components. Recent work has found that submerged surfaces can be kept free of biofouling using projected ultraviolet (UV) light from LEDs. This paper discusses the testing procedure and impact of the UVC irradiation on biofilm prevention within the active part of an electric generator in a systematic manner, with a view to accelerate its translation to full-scale applications. \u0000A prototype generator is being developed which will be installed in the North Sea, consisting of a submerged linear tubular electrical machine. A magnetic tubular translator will oscillate within a cylinder that houses stator coils. Lubrication will be by way of solid polymer bearings. In order that the active part of the electrical machine can oscillate smoothly, it is imperative that biofilm is prevented from colonising on the bearing surface, which also makes up the magnetic gap of the electrical machine. \u0000The system will have a slow reciprocating oscillation, with a peak speed of perhaps 2m/s. For most wave energy converters there will be brief static periods twice in every wave, and in calm seas these could be prolonged to several hours or even days. In low energy sea states oscillation amplitude could be less than the fully rated amplitude, meaning different parts of the bearing surface could be exposed for different amounts of time. \u0000Early-stage work is underway to investigate the use of UV irradiation in the active part of the electrical machine and bearing surface as biofilm prevention. Flat panels (600mm x 220mm) are used to simulate the original surfaces between moving parts. To achieve biofilm growth, an artificial slime farm was deployed which allows test panels to be subjected to a continuous dynamic flow. The light source of UV irradiation was provided by Light Emitting Diodes (LEDs) with 278nm wavelength. The effectiveness of the biofilm prevention by UVC were evaluated by Image Analysis \u0000The results indicate that UVC can significantly control biofilm presence on the panels. It also has demonstrated that intermittent UV can achieve successful biofilm prevention on submerged surfaces. However, observations ","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126527905","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. Pasta, B. Paduano, G. Mattiazzo, N. Faedo, J. Ringwood
The development of effective energy-maximising control strategies has a crucial role in the empowerment of wave energy technology, and in its improvement towards economic viability. Within the state-of-the-art, most of the strategies adopted to maximise the absorbed energy exploit a model of the wave energy converter (WEC) to be controlled, i.e. they are model-based. These models attempt to replicate the WEC dynamics with a sufficient degree of fidelity, trying, at the same time, to minimise their associated computational burden. However, due to the presence of the hydrodynamic effects , which inherently characterise wave energy systems, simultaneously achieving high-fidelity and computational efficiency is not trivial. Oversimplification of the problem through, for example, linearity assumptions, could lead to non-representative models and/or large uncertainty levels. To overcome these issues, in the last decade, several approaches based on data have been proposed in the wave energy field. These approaches, falling under the umbrella of system identification techniques, exploit data coming from experimental tests or high fidelity simulations, and build control -oriented models with a pre-defined level of complexity. In this paper, we analyse the different strategies that have been adopted in the literature to build data-based control-oriented models for WECs, highlighting the characteristics of each approach, together with their opportunities and inherent drawbacks. An analysis of eventual “partial” data-based modelling of WEC subsystems (e.g. moorings, PTO, or hydrodynamics only) is also reported. Moreover, considerations on the choice of inputs and outputs depending on the WEC type are reported, in an attempt to highlight the different issues that characterise the system identification problem depending on the WEC technology. Finally, conclusions are drawn regarding the capabilities that this type of approach has in (at least partially) solving the modelling issues that affect WEC control system design, and the pitfalls that pure adoption of these strategies has when applied on larger scales, or in the operational stage.
{"title":"On data-based control-oriented modelling applications in wave energy systems","authors":"E. Pasta, B. Paduano, G. Mattiazzo, N. Faedo, J. Ringwood","doi":"10.36688/ewtec-2023-409","DOIUrl":"https://doi.org/10.36688/ewtec-2023-409","url":null,"abstract":"The development of effective energy-maximising control strategies has a crucial role in the empowerment of wave energy technology, and in its improvement towards economic viability. Within the state-of-the-art, most of the strategies adopted to maximise the absorbed energy exploit a model of the wave energy converter (WEC) to be controlled, i.e. they are model-based. These models attempt to replicate the WEC dynamics with a sufficient degree of fidelity, trying, at the same time, to minimise their associated computational burden. However, due to the presence of the hydrodynamic effects , which inherently characterise wave energy systems, simultaneously achieving high-fidelity and computational efficiency is not trivial. Oversimplification of the problem through, for example, linearity assumptions, could lead to non-representative models and/or large uncertainty levels. To overcome these issues, in the last decade, several approaches based on data have been proposed in the wave energy field. These approaches, falling under the umbrella of system identification techniques, exploit data coming from experimental tests or high fidelity simulations, and build control -oriented models with a pre-defined level of complexity. In this paper, we analyse the different strategies that have been adopted in the literature to build data-based control-oriented models for WECs, highlighting the characteristics of each approach, together with their opportunities and inherent drawbacks. An analysis of eventual “partial” data-based modelling of WEC subsystems (e.g. moorings, PTO, or hydrodynamics only) is also reported. Moreover, considerations on the choice of inputs and outputs depending on the WEC type are reported, in an attempt to highlight the different issues that characterise the system identification problem depending on the WEC technology. Finally, conclusions are drawn regarding the capabilities that this type of approach has in (at least partially) solving the modelling issues that affect WEC control system design, and the pitfalls that pure adoption of these strategies has when applied on larger scales, or in the operational stage.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121293478","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}
Jeff Grasberger, Jonathan Bird, R. Coe, G. Bacelli, Carlos A. Michelén Ströfer, Alex Hagmüller
Complex conjugate impedance matching is a key concept for wave energy converter design. Matching the impedance of the power take-off (PTO) system to the complex conjugate of the wave energy converter's (WEC) impedance ensures efficient transfer of energy from the WEC body motion to electrical power. In low frequency waves, impedance matching often requires a negative PTO stiffness. In this paper, an adjustable stiffness magnetic torsion spring will be presented and modeled to understand its potential to improve WEC performance. The spring has the ability to provide a negative stiffness, allowing the PTO impedance to more closely match the complex conjugate of the WEC impedance at low frequencies. The spring also supports an adjustable stiffness value, meaning it can be tuned according to the incoming wave conditions. The spring's tunability may put less stress on the rest of the PTO system in wave conditions outside its normal operation zone without sacrificing electrical power output. The adjustable magnetic spring's effects are modeled and explored in this paper by examining the resultant average annual electrical power and capacity factor. The study suggests that the tunable magnetic spring has the potential to significantly improve capacity factor while maintaining a high average electrical power.
{"title":"Maximizing Wave Energy Converter Power Extraction by Utilizing a Variable Negative Stiffness Magnetic Spring","authors":"Jeff Grasberger, Jonathan Bird, R. Coe, G. Bacelli, Carlos A. Michelén Ströfer, Alex Hagmüller","doi":"10.36688/ewtec-2023-510","DOIUrl":"https://doi.org/10.36688/ewtec-2023-510","url":null,"abstract":"Complex conjugate impedance matching is a key concept for wave energy converter design. Matching the impedance of the power take-off (PTO) system to the complex conjugate of the wave energy converter's (WEC) impedance ensures efficient transfer of energy from the WEC body motion to electrical power. In low frequency waves, impedance matching often requires a negative PTO stiffness. In this paper, an adjustable stiffness magnetic torsion spring will be presented and modeled to understand its potential to improve WEC performance. The spring has the ability to provide a negative stiffness, allowing the PTO impedance to more closely match the complex conjugate of the WEC impedance at low frequencies. The spring also supports an adjustable stiffness value, meaning it can be tuned according to the incoming wave conditions. The spring's tunability may put less stress on the rest of the PTO system in wave conditions outside its normal operation zone without sacrificing electrical power output. The adjustable magnetic spring's effects are modeled and explored in this paper by examining the resultant average annual electrical power and capacity factor. The study suggests that the tunable magnetic spring has the potential to significantly improve capacity factor while maintaining a high average electrical power.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121406088","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}
Lilia Flores Mateos, Carwyn Frost, Nicholas Baker-Horne, Louise Kregting, Vincent Mc Cormack
Assessment of the upstream flow available to the tidal energy converters (TEC) is key to evaluate its performance. Simultaneously, TEC technology has been innovating on its concepts and designs to expand the potential sites to harvest energy generated by tidal currents and rivers. The Gkinetic CEFA 12 is an easy-to-deploy device suitable to operate on estuary environments. The design consists of two 1.2 m vertical axis turbines attached to the sides of a buoyant platform, which uses a bluff body to accelerate the incoming flow to the rotors. The device was deployed on a single point mooring enabling passive flow alignment. As part of the Vertical axis tidal turbines in Strangford lough project (VATTS), the upstream flow has been measured using acoustic doppler profilers (ADP) mounted on the TEC during its operation in Strangford lough. Recommendations of IEC-200 were followed when mounting the ADPs relative to Gkinetic. However, the continuous repositioning of the TEC according to the prevailing tidal regime affects the ADPs heading. The implications of the spatial variation of the rotor’s upstream velocity on the resource assessment and device performance are not clear since this situation is not typical.To investigate the spatial variation of the upstream velocity two ADCP deployment locations were made. A seabed (upward facing) ADCP as per the current standards and a device mounted (downward facing) ADCP upstream of the rotor plane. Evaluation of the influence of the following three factors were made: i) the ADPs direction repositioning according to prevailing tidal regime, ii) the proximity of the sensors to the sea-surface, and iii) the proximity of the sensors to the TEC.These three factors will be evaluated using ADP datasets collected at Strangford narrows during the VATTS project. The datasets were obtained at approximately the same location of the TEC operation. They enable the study of the following scenarios 1) incoming flow to the rotors during operation, 2) incoming flow on undisturbed conditions (no turbine operation), and 3) a harmonic analysis prediction of the undisturbed incoming flow, which solely captures the tidal-driven flow.The investigation of these three scenarios will provide a better understanding on the rotor’s upstream flow spatial variation, and the influence of the device’s proximity and near sea surface conditions on the mean flow. These findings would benefit developers of alternative TEC designs that operate near the sea-surface.
{"title":"Influence of the spatial variation of upstream velocity on a vertical-axis tidal turbine performance","authors":"Lilia Flores Mateos, Carwyn Frost, Nicholas Baker-Horne, Louise Kregting, Vincent Mc Cormack","doi":"10.36688/ewtec-2023-323","DOIUrl":"https://doi.org/10.36688/ewtec-2023-323","url":null,"abstract":"Assessment of the upstream flow available to the tidal energy converters (TEC) is key to evaluate its performance. Simultaneously, TEC technology has been innovating on its concepts and designs to expand the potential sites to harvest energy generated by tidal currents and rivers. The Gkinetic CEFA 12 is an easy-to-deploy device suitable to operate on estuary environments. The design consists of two 1.2 m vertical axis turbines attached to the sides of a buoyant platform, which uses a bluff body to accelerate the incoming flow to the rotors. The device was deployed on a single point mooring enabling passive flow alignment. As part of the Vertical axis tidal turbines in Strangford lough project (VATTS), the upstream flow has been measured using acoustic doppler profilers (ADP) mounted on the TEC during its operation in Strangford lough. Recommendations of IEC-200 were followed when mounting the ADPs relative to Gkinetic. However, the continuous repositioning of the TEC according to the prevailing tidal regime affects the ADPs heading. The implications of the spatial variation of the rotor’s upstream velocity on the resource assessment and device performance are not clear since this situation is not typical.To investigate the spatial variation of the upstream velocity two ADCP deployment locations were made. A seabed (upward facing) ADCP as per the current standards and a device mounted (downward facing) ADCP upstream of the rotor plane. Evaluation of the influence of the following three factors were made: i) the ADPs direction repositioning according to prevailing tidal regime, ii) the proximity of the sensors to the sea-surface, and iii) the proximity of the sensors to the TEC.These three factors will be evaluated using ADP datasets collected at Strangford narrows during the VATTS project. The datasets were obtained at approximately the same location of the TEC operation. They enable the study of the following scenarios 1) incoming flow to the rotors during operation, 2) incoming flow on undisturbed conditions (no turbine operation), and 3) a harmonic analysis prediction of the undisturbed incoming flow, which solely captures the tidal-driven flow.The investigation of these three scenarios will provide a better understanding on the rotor’s upstream flow spatial variation, and the influence of the device’s proximity and near sea surface conditions on the mean flow. These findings would benefit developers of alternative TEC designs that operate near the sea-surface.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122275782","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}
This paper will report on work being undertaken to evaluate the performance of the counter-rotating tidal turbine in a wave-current coupled operation environment based on Blade Element Momentum Theory (BEMT). The counter-rotating tidal turbine has two rotors rotating in opposite directions on the same axis. It has been proposed on the basis of the theory, which states that a configuration of two rotors having a similar swept area on the same axis has a higher maximum power coefficient than a conventional configuration of a wind turbine with a single rotor. BEMT is a reliable and effective theory for rotor design because it is based on solid physical principles and has a remarkably low computing cost.
{"title":"THE PERFORMANCE OF COUNTER-ROTATING TIDAL TURBINE IN DIFFERENT SEA STATES","authors":"Song Fu","doi":"10.36688/ewtec-2023-506","DOIUrl":"https://doi.org/10.36688/ewtec-2023-506","url":null,"abstract":"This paper will report on work being undertaken to evaluate the performance of the counter-rotating tidal turbine in a wave-current coupled operation environment based on Blade Element Momentum Theory (BEMT). The counter-rotating tidal turbine has two rotors rotating in opposite directions on the same axis. It has been proposed on the basis of the theory, which states that a configuration of two rotors having a similar swept area on the same axis has a higher maximum power coefficient than a conventional configuration of a wind turbine with a single rotor. BEMT is a reliable and effective theory for rotor design because it is based on solid physical principles and has a remarkably low computing cost.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"2 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125918494","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}
S.W. Tucker Harvey, Xiaosheng Chen, D. Rowe, J. McNaughton, C.R. Vogel, K. Bhavsar, T. Allsop, J. Gilbert, H. Mullings, T. Stallard, A. Young, I. Benson, R. Willden
The tidal turbine benchmarking project, funded by the UK's EPSRC and the Supergen ORE Hub, has conducted a large laboratory scale experiment on a highly instrumented 1.6m diameter tidal rotor. The turbine is instrumented for the measurement of spanwise distributions of flapwise and edgewise bending moments using strain gauges and a fibre Bragg optical system, as well as overall rotor torque and thrust. The turbine was tested in well-defined flow conditions, including grid-generated freestream turbulence, and was towed through the 12.2m wide, 5.4m deep long towing tank at Qinetiq’s Haslar facility. The turbine scale was such that blade Reynolds numbers were Re=3x10^5 and therefore post-critical, whilst turbine blockage was kept low at 3.1. In order to achieve higher levels of freestream turbulence a 2.4m by 2.4m turbulence grid was towed 5m upstream of the turbine. Measurements to characterise the grid generated turbulence were made at the rotor plane using an Acoustic Doppler Velocimeter and a five-hole pressure probe. An elevated turbulence of 3.1% with homogeneous flow speed across the rotor plane was achieved using the upstream turbulence grid. The experimental tests are well defined and repeatable, and provide relevant data for validating models intended for use in the design and analysis of full-scale turbines. This paper reports on the first experimental stage of the tidal benchmarking programme, including the design of the rotor and comparisons of the experimental results to blade resolved numerical simulations.
{"title":"Tidal Turbine Benchmarking Project: Stage I - Steady Flow Experiments","authors":"S.W. Tucker Harvey, Xiaosheng Chen, D. Rowe, J. McNaughton, C.R. Vogel, K. Bhavsar, T. Allsop, J. Gilbert, H. Mullings, T. Stallard, A. Young, I. Benson, R. Willden","doi":"10.36688/ewtec-2023-553","DOIUrl":"https://doi.org/10.36688/ewtec-2023-553","url":null,"abstract":"The tidal turbine benchmarking project, funded by the UK's EPSRC and the Supergen ORE Hub, has conducted a large laboratory scale experiment on a highly instrumented 1.6m diameter tidal rotor. The turbine is instrumented for the measurement of spanwise distributions of flapwise and edgewise bending moments using strain gauges and a fibre Bragg optical system, as well as overall rotor torque and thrust. The turbine was tested in well-defined flow conditions, including grid-generated freestream turbulence, and was towed through the 12.2m wide, 5.4m deep long towing tank at Qinetiq’s Haslar facility. The turbine scale was such that blade Reynolds numbers were Re=3x10^5 and therefore post-critical, whilst turbine blockage was kept low at 3.1.\u0000In order to achieve higher levels of freestream turbulence a 2.4m by 2.4m turbulence grid was towed 5m upstream of the turbine. Measurements to characterise the grid generated turbulence were made at the rotor plane using an Acoustic Doppler Velocimeter and a five-hole pressure probe. An elevated turbulence of 3.1% with homogeneous flow speed across the rotor plane was achieved using the upstream turbulence grid.\u0000The experimental tests are well defined and repeatable, and provide relevant data for validating models intended for use in the design and analysis of full-scale turbines. This paper reports on the first experimental stage of the tidal benchmarking programme, including the design of the rotor and comparisons of the experimental results to blade resolved numerical simulations.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114174225","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 well known to be a renewable energy resource with worldwide capacity similar to wind. However there is to date negligible generation of electricity from wave. Many devices have been proposed without convergence on a particular design as there has been for wind. We are here concerned with a multi-float attenuator type M4 which has been widely tested in wave basins and modelled by linear diffraction/radiation methods. Potential of MW capacity for grid supply has been demonstrated at many sites. To advance development, small scale ocean tests are being planned for Albany, Western Australia where summer wind-wave conditions in King George Sound will excite the device giving principal absorption with mean periods in the range 2 - 3.5 seconds (or peak periods of 2.5 – 4.5 s). The aim is to learn about most aspects of ocean deployment from wave climate and environment planning to realistic electricity generation, albeit at kW scale. In this paper the emphasis is on the specification of electrical drive train (power take off) which requires the input of torque time variation for the wave conditions on the site, as described by a scatter diagram. First a linear time domain wave multi-float model (Fortran) is set up for the particular 121 configuration, shown in Fig. 1. Such models have been used and validated against wave basin tests for similar configurations. This is then converted into state-space form in Matlab. This is highly efficient and suited for real time PTO control in Simulink. Fig. 2 shows the main components of the electrical drive train, including the gearbox, generator, super-capacitors, power electronic converters and resistor bank to dissipate electricity. Bespoke Matlab models will be run for the wave conditions in the scatter diagram to check that components are suitably rated for normal sea-states, and are safely protected through electrical power-limiting control in high sea states. Simulated electrical generator results will be shown for typical sea states, with some power-limiting. Instrumentation will be specified. Only uni-directional waves are considered in this paper. Ultimately the efficacy of the system will be demonstrated in ocean conditions.
{"title":"Integrated hydrodynamic-electrical hardware model for wave energy conversion with M4 ocean demonstrator","authors":"Judith Apsley, Xiaotao Zhang, Matteo Iacchetti, Inaki Erazo Damian, Zhijing Liao, Gangqiang Li, Peter Stansby, Guang Li, Hugh Wolgamot, Christophe Gaudin, Adi Kurniawan, Xinan Zhang, Zifan Lin, Nuwantha Fernando, Chris Shearer, Brad Saunders","doi":"10.36688/ewtec-2023-500","DOIUrl":"https://doi.org/10.36688/ewtec-2023-500","url":null,"abstract":"Wave energy is well known to be a renewable energy resource with worldwide capacity similar to wind. However there is to date negligible generation of electricity from wave. Many devices have been proposed without convergence on a particular design as there has been for wind. We are here concerned with a multi-float attenuator type M4 which has been widely tested in wave basins and modelled by linear diffraction/radiation methods. Potential of MW capacity for grid supply has been demonstrated at many sites. To advance development, small scale ocean tests are being planned for Albany, Western Australia where summer wind-wave conditions in King George Sound will excite the device giving principal absorption with mean periods in the range 2 - 3.5 seconds (or peak periods of 2.5 – 4.5 s). The aim is to learn about most aspects of ocean deployment from wave climate and environment planning to realistic electricity generation, albeit at kW scale. In this paper the emphasis is on the specification of electrical drive train (power take off) which requires the input of torque time variation for the wave conditions on the site, as described by a scatter diagram. First a linear time domain wave multi-float model (Fortran) is set up for the particular 121 configuration, shown in Fig. 1. Such models have been used and validated against wave basin tests for similar configurations. This is then converted into state-space form in Matlab. This is highly efficient and suited for real time PTO control in Simulink. Fig. 2 shows the main components of the electrical drive train, including the gearbox, generator, super-capacitors, power electronic converters and resistor bank to dissipate electricity. Bespoke Matlab models will be run for the wave conditions in the scatter diagram to check that components are suitably rated for normal sea-states, and are safely protected through electrical power-limiting control in high sea states. Simulated electrical generator results will be shown for typical sea states, with some power-limiting. Instrumentation will be specified. Only uni-directional waves are considered in this paper. Ultimately the efficacy of the system will be demonstrated in ocean conditions.","PeriodicalId":201789,"journal":{"name":"Proceedings of the European Wave and Tidal Energy Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121361782","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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