Preface
Contents
Contributors
1 Wave Energy Potential
1.1 World Energy Outlook
1.2 Ocean Energy
1.3 Environmental Impacts
1.4 Tidal Datum
1.5 Importance of Wave Energy
1.6 Wave Power Potential
1.6.1 Methods of Evaluation
1.6.2 Estimated Wave Power Potential
1.7 Wave Energy Map for INDIA
References
2 Wave Energy Convertors
2.1 General
2.2 Harnessing of Wave Energy
2.3 Conversion Process
2.4 Wave Energy Devices
2.5 Wave Energy Developments and Activities
2.5.1 General
2.5.2 Shoreline Wave Energy System
2.5.3 Near Shore Wave Energy System
2.5.4 Offshore Wave Energy Systems
2.6 Onshore/Nearshore OWC Wave Energy Devices
2.7 Offshore OWC Wave Energy Devices
2.8 Special Types of Breakwaters with WEC
2.9 Summary
References
3 Direct Absorber for Wave Energy Conversion
3.1 Introduction
3.1.1 Wave Energy Physics and Resource
3.2 Theoretical Background and Governing Equations
3.2.1 Linear Wave Theory of Ocean Surface (LWT)
3.2.2 Dispersion Relation
3.2.3 Energy in Water Wave
3.2.4 Wave Energy Spectrum
3.2.5 Forces on Floating Bodies
3.3 Wave Energy Conversion Systems
3.3.1 Attenuator
3.3.2 Oscillating Wave Surge Converter
3.3.3 Oscillating Water Column
3.3.4 Overtopping Device
3.3.5 Submerged Pressure
3.3.6 Point Absorber
3.4 Conclusion
References
4 Development of Oscillating Water Column and Wave Overtopping—Wave Energy Converters in Europe Over the Years
4.1 The Importance of Wave Energy Resources Utilisation
4.2 A Brief Introduction to Wave Energy Harvesting Mechanism
4.3 Oscillating Water Column (OWC) Type Wave Energy Converter
4.3.1 General Introduction of OWC
4.3.2 Working Principle and Design Analysis of OWC
4.4 Oscillating Water Column Type WEC Projects Developments History
4.4.1 Land Installed Marine Power Energy Transmitter (LIMPET)
4.4.2 Pico Power Plant
4.4.3 Mutriku Wave Energy Plant
4.4.4 Resonant Wave Energy Converter (REWEC) or U-OWC
4.4.5 Siadar Wave Power Project
4.4.6 Floating OWC Development
4.5 Brief Summary of Wave Overtopping Devices’ Development Over the years
4.5.1 General Introduction to Wave Overtopping Mechanism
4.5.2 Wave Loadings Analysis and Development of Sea-Wave Slot-Cone Generator (SSG)
4.5.3 Overtopping BReakwater for Energy Conversion (OBREC) Development
References
5 Performance Characteristics of an OWC in Regular and Random Waves
5.1 Introduction
5.2 Experimental Investigations
5.2.1 OWC Model
5.2.2 Experimental Program
5.2.3 Harbour Walls in OWC
5.2.4 Wave Characteristics for the Study
5.2.5 Hydrodynamic Factors
5.3 Results and Discussion
5.3.1 Regular Wave Tests
5.3.2 Random Waves
5.3.3 OWC with Inclined Harbour Walls in Regular and Random Wave Fields
5.4 Summary and Conclusions
References
6 Wave Induced Pressures and Forces on an OWC Device
6.1 Introduction
6.2 Literature Review
6.3 Experimental Investigation
6.3.1 Test Facility
6.3.2 Test Model and Experimental Set-Up
6.3.3 Instrumentation
6.3.4 Wave Characteristics
6.4 Hydrodynamic Parameters
6.5 Results and Discussion
6.5.1 Time Histories of Measured Signatures
6.5.2 Pressure Distribution in Front of the Lip Wall
6.5.3 Pressure Distribution at the Rear Wall of OWC Device
6.5.4 Air Pressure Inside the OWC Caisson
6.5.5 Horizontal Wave Force
6.5.6 Vertical Wave Force
6.5.7 Comparison of Measured and Estimated Horizontal Wave Force
6.5.8 Total Horizontal and Vertical Wave Forces Due to Random Waves
6.6 Summary and Conclusions
References
7 Hydrodynamic Performance Characteristics of U-OWC Devices
7.1 Introduction
7.2 Experimental Set-Up
7.2.1 General
7.2.2 Details of the Models and Test Set-Up
7.2.3 Test Facility
7.2.4 Experimental Procedure
7.3 Results and Discussion
7.3.1 Spectral Width Parameter
7.3.2 Dynamic Pressures
7.3.3 Energy Efficiency
7.3.4 Air Pressure Variation
7.3.5 Phase Difference
7.3.6 Wave Amplification
7.4 Conclusions
References
8 CFD Modelling of OWC Devices for Wave Energy Harnessing
8.1 Introduction
8.2 The Numerical Experiment
8.2.1 Computational Domain
8.2.2 Mesh
8.2.3 Boundary Conditions
8.3 Governing Equations
8.3.1 Pressure-Based Solver
8.3.2 Pressure–Velocity Coupling
8.3.3 Solution Control Parameters
8.4 Under-Relaxation Factors
8.4.1 Spatial Discretization of Equations
8.4.2 Reconstruction of Gradients
8.4.3 Time Discretization
8.5 Multiphase Flow
8.5.1 The Volume of Fluid (VOF)
8.6 Explicit Scheme
8.7 Implicit Scheme
8.7.1 Interpolation Near the Water–air Interface
8.7.2 Wave Generation
8.7.3 Dynamic Mesh
8.8 Dynamic Mesh Update
8.9 Elastic Smoothing Method
8.9.1 Open Channel Boundary Condition
8.10 PTO System and Configuration of the Porous Medium Region
8.11 Simulation, Data Saving, and Post-Processing
8.12 Conclusions
References
9 Numerical Modelling Techniques for Wave Energy Converters in Arrays
9.1 Introduction
9.2 Review of Hydrodynamic Modelling of WEC Arrays
9.2.1 Point Absorber Method
9.2.2 Plane-Wave Method
9.2.3 Multiple Scattering
9.2.4 Direct Matrix Method
9.2.5 Geographical Scale Studies
9.3 Boundary Element Methods
9.3.1 Problem Definition
9.3.2 Mathematical Formulation
9.3.3 Generated Power and Interaction Factor
9.3.4 Wave Disturbance Under Multi-Directional Sea
9.4 Verification of the Numerical Model
9.4.1 Performance of Arrays
9.5 WEC Array Modelling by Ocean Scale Numerical Models
9.5.1 Numerical Model Set-Up
9.5.2 Predictions Without Energy Extraction
9.5.3 Implementation of Energy Extraction
9.6 Concluding Remarks
References
10 Hydrodynamic Performance of an Array of OWC Devices Integrated with Breakwater
10.1 Introduction
10.2 Experimental Investigation
10.2.1 Test Facility
10.2.2 Data Acquisition Sensors
10.2.3 Test Model and Experimental Setup
10.2.4 Instrumentation
10.2.5 Wave Characteristics and Hydrodynamic Parameters
10.3 Results and Discussion
10.3.1 Time Histories
10.3.2 Effect of Wave Characteristics
10.3.3 Wave Interaction Between Devices
10.3.4 Effect of Spacing
10.3.5 Performance of OWC in an Array
10.3.6 Total Performance vs. Average Performance
10.3.7 Reflection Nature of OWCBW System
10.4 Hydrodynamic Performance of OWCBW System Subjected to Oblique Wave Incidence
10.5 Summary and Conclusions
10.5.1 The Salient Conclusions Drawn from the Studies Are
References
11 Power Take-Off Devices for Wave Energy Converters
11.1 Introduction to Wave Energy
11.2 Types of Power Take-Off Mechanisms Used in Point Absorbers
11.2.1 Air Turbines
11.2.2 Hydraulic Converters
11.2.3 Hydro Turbines
11.2.4 Direct Mechanical Drive Systems
11.2.5 Direct Electrical Drive Systems
11.3 Conclusion
References
12 Wells Turbine as a Power Take-Off Mechanism for Wave Energy Converters
12.1 Introduction
12.2 Historical Overview
12.3 Wells Turbine: Principle of Operation
12.4 Variations of Wells Turbine
12.4.1 Monoplane Wells Turbine
12.5 Turbines with Guide Vane
12.6 Turbines with Non-zero Pitch Angles
12.7 Turbines with Variable Pitch Angles
12.8 Unsteady Flow Analysis
12.9 Starting Characteristics of Wells Turbine
12.10 Optimization of Air Turbines
12.11 Conclusion
References
13 Experimental Testing of Air Turbines for Wave Energy Conversion
13.1 Introduction
13.2 Experimental Setup
13.3 Instrumentation: Sensors and Data Acquisition Systems
13.4 Generator Selection
13.5 Generator Characteristics
13.6 Experimental Procedure
13.7 Experimental Testing of an Impulse Turbine
13.7.1 Design and Fabrication
13.7.2 No-Load Test
13.7.3 Performance of the Turbine
13.7.4 Power Calculation: Load Test
13.8 Experimental Testing of a Wells Turbine
13.8.1 Design and Fabrication
13.8.2 Starting Characteristics
13.8.3 No-Load Test
13.8.4 Test with Resistive Loading
13.9 Uncertainty Analysis
13.10 Conclusions
References
14 Passive Flow Control Methods for Performance Augmentation in Air Turbines Used for Wave Energy Conversion—A Review
14.1 Wave Energy
14.2 Oscillating Water Column
14.3 Air Turbines for Wave Energy Conversion
14.3.1 Wells Turbine
14.3.2 Axial Impulse Turbine
14.4 Flow Control Methods
14.5 Passive Flow Control Methods in Wells Turbine
14.5.1 Blade Sweep
14.5.2 Blade Setting Angle
14.5.3 Penetrating Ring and Endplate at the Blade Tip
14.5.4 Non-uniform Tip Clearance
14.5.5 Variable Chord Blade
14.5.6 Casing Groove
14.5.7 Suction Slots
14.5.8 Variable Thickness Blade
14.5.9 Leading-Edge Undulation
14.5.10 Radiused Edge Tip Blade
14.5.11 Static Extended Trailing Edge (SETE)
14.5.12 Gurney Flap
14.5.13 Combined Radiused Edge Tip, Static Extended Trailing Edge, and Variable Thickness Blade
14.6 Passive Flow Control Methods in Axial Impulse Turbine
14.6.1 Endplates
14.6.2 Blade Setting Angle
14.6.3 Penetration Ring
14.6.4 Leaned Blade
14.7 Conclusions
References
15 Optimization of an Impulse Turbine for Efficient Wave Energy Extraction
15.1 Introduction
15.2 Oscillating Water Column
15.3 Turbine Selection for OWC
15.4 Numerical Studies on Impulse Turbine
15.4.1 Background Study
15.4.2 Steps Involved in Performing CFD Simulations
15.4.3 Case Study on CFD Simulations for an Impulse Turbine for Wave Energy Extraction
15.5 Optimization
15.5.1 Design Variable and Objective Function
15.5.2 Design Space
15.5.3 Use of Surrogates Method to Populate Sampling Points
15.5.4 Genetic Algorithm as an Optimizer
15.6 Results and Discussions Based on Optimization of Impulse Turbine
15.6.1 Design Space
15.6.2 Sensitivity of Design Variable
15.6.3 Results from Optimization Algorithm
15.6.4 Results for Optimized Turbine Over Wide Flow Range
15.6.5 Parametric Sensitivity Analysis
15.7 Closure
References
16 Control of Wave Energy Converters
16.1 Introduction
16.2 Control Techniques Applied to WECs
16.2.1 Control of WEC Primary Parameters
16.2.2 Airflow Control
16.2.3 Control of Secondary Converters
16.3 Conclusion
References
17 Recent Advances in Direct-Drive Power Take-Off (DDPTO) Systems for Wave Energy Converters Based on Switched Reluctance Machines (SRM)
17.1 Introduction
17.2 Power Take-Off (PTO) in Wave Energy Converters
17.2.1 Introduction to PTO-Concept
17.2.2 Introduction to the Different Types of PTOs
17.3 Direct-Drive Power Take-Off: SRM Topology
17.3.1 Introductory Aspects
17.3.2 Example of an Analysis of a WEC with a DDPTO
17.3.3 The Linear Switched Reluctance Machine (LSRM)
17.3.4 SRM Power Electronics and Control
17.4 Superconducting Linear Switched Reluctance Machine (LSRM)
17.4.1 Introduction
17.4.2 The Importance of High Force/High Efficiency PTOs
17.4.3 Some Simple Concepts on Superconductivity and Cryogenics
17.4.4 Options for Superconducting Machines: A Superconducting PTO
17.5 Concluding Remarks
References
18 Grid Integration of Wave Energy Devices
18.1 Introduction: Wave Energy Impacts in Electric Grid
18.1.1 Impact in the Power Grid of Renewable Energy
18.1.2 Current Status and Perspectives of Ocean Energy
18.1.3 Problems with the Grid Integration of Wave Energy Converters
18.2 Power Oscillations in Wave Energy Generation
18.2.1 Wave Energy Resource: Characterization of Oscillations
18.2.2 Evaluation of Electric Power Oscillations in Wave Energy Converters
18.2.3 Evaluation of Impacts on the Electric Grid
18.3 Analysis of Smoothing Power Solutions
18.3.1 Introduction: Relevant Solutions for Wave Power Smoothing
18.3.2 Analysis of Energy Storage as Power Smoothing Solution
18.4 Integration of Energy Storage System in Wave Energy Converters: Industrial Examples
References