Periodic Reporting for period 2 - LiftWEC (Development of a novel wave energy converter based on hydrodynamic lift forces)
Okres sprawozdawczy: 2021-06-01 do 2023-03-31
The LiftWEC project involves the development of a novel wave energy converter whose primary coupling with the waves is through the generation of hydrodynamic lift on a rotating hydrofoil. That is, the wave energy converter consists of a hydrofoil that is driven by the waves to rotate around an axis orthogonal to the principal wave direction. Useful energy can then be extracted from the system using a generating element which acts to resist the motion of the hydrofoil. Thus, the LiftWEC concept has many similarities to wind turbines, which in recent years have shown that renewable energy can be readily generated both practically and economically.
Literature studies and patent searches indicate that of the many hundreds of wave energy converter concepts that have been developed, only a few are based on hydrodynamic lift, whilst the vast majority of devices seek to exploit either the buoyancy or diffraction force regimes. However, using hydrodynamic lift in a wave energy converter has a number of significant advantages including; (1) the reduction of extreme loads through feathering the hydrofoil, also like a wind turbine, which improves survivability, and (2) unidirectional rotation, which significantly simplifies power extraction over traditional wave energy converters which typically involve reciprocating motions.
The overall objective of the LiftWEC project was to determine the potential for using lift in wave energy converters to produce renewable energy at a commercially competitive price whilst ensuring a minimal environmental/social impact. This was achieved by a combination of numerical/physical modelling and desk-based studies relating to structural design, operational & maintenance requirements, levelized cost of energy and environmental/social impacts of the technology. During the course of the project, the LiftWEC concept was taken to Technology Readiness Level 4. A holistic, whole system design approach was taken by the project in an attempt to overcome many of the issues that have previously challenged the wave energy industry.
At project close, the LiftWEC project has been successful in its various endeavours. Specifically the work has culminated in the outline design of a lift-based wave energy converter that was shown to have an estimated Levelized Cost of Energy that may be considered competitive in the renewable energy marketplace.
Literature studies and patent searches indicate that of the many hundreds of wave energy converter concepts that have been developed, only a few are based on hydrodynamic lift, whilst the vast majority of devices seek to exploit either the buoyancy or diffraction force regimes. However, using hydrodynamic lift in a wave energy converter has a number of significant advantages including; (1) the reduction of extreme loads through feathering the hydrofoil, also like a wind turbine, which improves survivability, and (2) unidirectional rotation, which significantly simplifies power extraction over traditional wave energy converters which typically involve reciprocating motions.
The overall objective of the LiftWEC project was to determine the potential for using lift in wave energy converters to produce renewable energy at a commercially competitive price whilst ensuring a minimal environmental/social impact. This was achieved by a combination of numerical/physical modelling and desk-based studies relating to structural design, operational & maintenance requirements, levelized cost of energy and environmental/social impacts of the technology. During the course of the project, the LiftWEC concept was taken to Technology Readiness Level 4. A holistic, whole system design approach was taken by the project in an attempt to overcome many of the issues that have previously challenged the wave energy industry.
At project close, the LiftWEC project has been successful in its various endeavours. Specifically the work has culminated in the outline design of a lift-based wave energy converter that was shown to have an estimated Levelized Cost of Energy that may be considered competitive in the renewable energy marketplace.
The LiftWEC project has been building a foundation of knowledge on lift-based wave energy converters that can be used to help identify the potential for this type of wave energy converter. Work has been performed to help understand the hydrodynamics, control, structural design, operational and maintenance requirements, cost of energy, and the environment and social impact of such systems.
An understanding of the fundamental hydrodynamics of lift-based wave energy converters has been developed using various numerical models. A computational fluid dynamic model has been developed and used to investigate the fundamental performance for using a hydrofoil to generate lift and achieve unidirectional rotation in waves. In addition, a potential flow model has been developed to investigate how the hydrofoil should be controlled to maximise power capture. This model has been used to develop robust and reliable control system for the device. Finally, a far-field wave model has been developed to determine the fundamental hydrodynamic properties of the device and to investigate how the primary device dimensions may influence the maximum theoretical performance. Two sets of 20th scale physical wave tank testing have been also completed in both 2D and 3D.
Work began with the development of 17 "Preliminary LiftWEC Configurations". The effects of key design parameters such as the hydrofoil span, radius, chord length etc. were investigated to provide guidance for design. Similarly, the installation and operational & maintenance requirements for different LiftWEC configurations have been modelled and implications for the design of lift-based wave energy converters identified. These preliminary configurations were then refined down to four "Baseline LiftWEC Configurations" which formed the basis of the second phase of project efforts. Work completed in this second phase led to the selection of the "Final LiftWEC Configuration" which was deemed to hold the greatest potential for commercialisation. Various technical assessments of this Final LiftWEC Configuration have been completed and the results of the project have been widely disseminated in peer-reviewed research articles as well as in numerous public forums such as in the form of both project deliverables and public presentations.
An understanding of the fundamental hydrodynamics of lift-based wave energy converters has been developed using various numerical models. A computational fluid dynamic model has been developed and used to investigate the fundamental performance for using a hydrofoil to generate lift and achieve unidirectional rotation in waves. In addition, a potential flow model has been developed to investigate how the hydrofoil should be controlled to maximise power capture. This model has been used to develop robust and reliable control system for the device. Finally, a far-field wave model has been developed to determine the fundamental hydrodynamic properties of the device and to investigate how the primary device dimensions may influence the maximum theoretical performance. Two sets of 20th scale physical wave tank testing have been also completed in both 2D and 3D.
Work began with the development of 17 "Preliminary LiftWEC Configurations". The effects of key design parameters such as the hydrofoil span, radius, chord length etc. were investigated to provide guidance for design. Similarly, the installation and operational & maintenance requirements for different LiftWEC configurations have been modelled and implications for the design of lift-based wave energy converters identified. These preliminary configurations were then refined down to four "Baseline LiftWEC Configurations" which formed the basis of the second phase of project efforts. Work completed in this second phase led to the selection of the "Final LiftWEC Configuration" which was deemed to hold the greatest potential for commercialisation. Various technical assessments of this Final LiftWEC Configuration have been completed and the results of the project have been widely disseminated in peer-reviewed research articles as well as in numerous public forums such as in the form of both project deliverables and public presentations.
The state-of-the-art in lift-based wave energy converter at the start of this project consisted of a single configuration being actively developed by a commercial entity. Early in the LiftWEC project, an additional seventeen potential configurations were identified, increasing the scope and diversity of potential configurations for this under-investigated class of wave energy converter. The increase in number of potential configurations being investigated means that there is a greater probability that a commercially viable configuration of this type of wave energy converter will be identified. At project close, the most promising configuration has now been identified and significant technical works have gone into the development of this concept.
In addition, the project has developed a variety of novel numerical models and research methods that can be used to investigate the response, performance, loading and commercial/environmental/societal viability of lift-based wave energy converters. Many of these methods did not exist/had not been published prior to the completion of the project. Furthermore, the project has also published 14 of open source datasets, including the first every publicly available wave tank testing results for this class of wave energy converter.
At the end of the project, the state-of-the-art has been significantly advanced in the modelling and analysis of lift-based wave energy converters, as well as the assessment of their commercial potential. The state-of-the-art has been advanced with the production of numerical models that provide higher fidelity and greater insight into the hydrodynamics and structural design of lift-based wave energy converters. The state-of-the-art in control has also been advanced with the identification of control strategies that significantly increase device power capture. Finally, a method for estimating the peak possible power capture of the device has been developed. This work has revealed many of the fundamental hydrodynamics which explicitly detail how this type of device operates. This knowledge did not exist prior to the LiftWEC project.
In addition, the project has developed a variety of novel numerical models and research methods that can be used to investigate the response, performance, loading and commercial/environmental/societal viability of lift-based wave energy converters. Many of these methods did not exist/had not been published prior to the completion of the project. Furthermore, the project has also published 14 of open source datasets, including the first every publicly available wave tank testing results for this class of wave energy converter.
At the end of the project, the state-of-the-art has been significantly advanced in the modelling and analysis of lift-based wave energy converters, as well as the assessment of their commercial potential. The state-of-the-art has been advanced with the production of numerical models that provide higher fidelity and greater insight into the hydrodynamics and structural design of lift-based wave energy converters. The state-of-the-art in control has also been advanced with the identification of control strategies that significantly increase device power capture. Finally, a method for estimating the peak possible power capture of the device has been developed. This work has revealed many of the fundamental hydrodynamics which explicitly detail how this type of device operates. This knowledge did not exist prior to the LiftWEC project.