Renewable Energy from the Oceans: From wave, tidal and gradient systems to offshore wind and solar

Cover
Title
Copyright
Contents
Preface
List of contributing authors
1 A review of progress on ocean energies
    1.1 A risky business
    1.2 In the beginning
    1.3 Shocks to the system
    1.4 The challenge of ocean energy
    1.5 Technology Readiness Levels
    1.6 Wave energy – TRL 7
    1.7 Tidal and current energy
        1.7.1 Tidal range – TRL 9
        1.7.2 Tidal stream – TRL 8
    1.8 Thermal and salinity gradient systems
        1.8.1 Ocean thermal energy conversion – TRL 8
        1.8.2 Salinity gradient – TRL 4
    1.9 Offshore wind – TRL 8
    1.10 Marine solar
    1.11 Enabling technologies and actions
    References
2 Wave energy
    2.1 The wave resource
        2.1.1 Wave resource assessment
        2.1.2 Wave measurements
    2.2 Wave energy devices
        2.2.1 The ISWEC plant at Pantelleria
        2.2.2 Harbour breakwaters for wave energy conversion
        2.2.3 Overview of the development of a pivoting buoy system
    2.3 PTO development
        2.3.1 Introduction
        2.3.2 Design and test methods
        2.3.3 Innovative PTOs
        2.3.4 Magnetic gears
        2.3.5 Dielectric elastomer PTO
        2.3.6 Electromechanical ballscrew-based PTO
        2.3.7 Conclusions
    2.4 Modelling and control
        2.4.1 WEC models
        2.4.2 WEC control
    References
3 Tidal and current energy
    3.1 Introduction
        3.1.1 Characteristics of tidal current energy
        3.1.2 Basic physics of tidal energy
    3.2 The resource
    3.3 Tidal rise and fall concepts
        3.3.1 Tidal barrages
        3.3.2 Tidal lagoons
        3.3.3 Dynamic tidal power barriers
        3.3.4 Turbines for tidal rise and fall schemes
    3.4 Tidal bridges and fences
    3.5 Tidal, ocean current and river HKTs
    3.6 Differences between hydrokinetic and wind energy
        3.6.1 Limited depth suitable for turbines
        3.6.2 Tidal and ocean current flow velocities are lower than wind
        3.6.3 Much higher fluid density
        3.6.4 Cavitation
        3.6.5 Predictability
        3.6.6 Bidirectional flow
        3.6.7 Limited flow field
        3.6.8 Floating debris
    3.7 Axial flow turbines
    3.8 Crossflow turbines
    3.9 Ducts and diffusers
    3.10 ‘Flying’ turbines
    3.11 Oscillating foils
    3.12 Vortex shedding
    3.13 Tidal sails
    3.14 Arrays
        3.14.1 Tidal farm layout
        3.14.2 Mixing and wake recovery – streamwise and lateral spacing
    3.15 Economics
    3.16 Actual progress to date on large-scale grid-connected hydrokinetic power
    3.17 Case study – development of GEM, a tidal stream energy system
        3.17.1 GEM system configuration
        3.17.2 Turbine and diffuser experimental tests (small-scale models)
        3.17.3 Tests on full model in small scale
        3.17.4 Full-scale prototype tests
    Symbols used
    References
4 Thermal and salinity gradient systems
    4.1 Energy resources
        4.1.1 Oceanic thermal gradients
        4.1.2 Salinity gradients
    4.2 Ocean thermal energy conversion (OTEC) plants
        4.2.1 Open-cycle plants
        4.2.2 Closed-cycle plants
        4.2.3 Hybrid-cycle plants
        4.2.4 Feed-pump removal technique
        4.2.5 OTEC and solar pond
        4.2.6 OTEC systems characteristics
        4.2.7 Environmental impact
        4.2.8 Economic aspects
    4.3 Salinity gradient energy (SGE) plants
        4.3.1 Pressure-retarded osmosis membrane (PRO) plants
        4.3.2 Reverse electrodialysis (RED) plants
        4.3.3 Electric Double-Layer Capacitors plants
        4.3.4 Faradaic pseudo-capacitor plants
        4.3.5 SGE systems characteristics
        4.3.6 Environmental impact
        4.3.7 Economic aspects
    Acknowledgments
    List of acronyms
    References
5 Offshore wind energy
    5.1 Offshore wind characterisation
        5.1.1 The random nature of wind
        5.1.2 Long-term offshore wind speed characteristics
        5.1.3 Turbulence
        5.1.4 Wake flow effects
        5.1.5 Other offshore-specific conditions
    5.2 Wind turbine technology development: a historical perspective
    5.3 Basic principles of wind turbine operation
        5.3.1 Energy conversion and concentration
        5.3.2 One-dimensional momentum and Betz
        5.3.3 1D momentum with rotational wake
        5.3.4 Basic aerofoil principles
        5.3.5 BEM theory
        5.3.6 Basic corrections to BEM
    5.4 Offshore wind turbine control systems
        5.4.1 Control system fundamentals
        5.4.2 Steady-state control
        5.4.3 Dynamic control
        5.4.4 Advanced control for load suppression
    5.5 The future of offshore wind turbine technology
    Acknowledgements
    References
6 Marine solar energy
    6.1 Solar cell technology
        6.1.1 Semiconductor properties and growth
        6.1.2 Semiconductor properties: the P–N junction
        6.1.3 Crystalline solar cells
        6.1.4 Thin film solar cells
    6.2 Solar systems
        6.2.1 Solar panels
    6.3 Floating solar systems
        6.3.1 Motivation
        6.3.2 Components of a floating system
        6.3.3 Chronology
        6.3.4 Advantages and disadvantages
        6.3.5 Systems at sea: motivation and special challenges
        6.3.6 Systems at sea: current situation
        6.3.7 Offshore solar: the future
    References
7 Offshore support structure design
    7.1 Offshore support structures
        7.1.1 Bottom-fixed support structures
        7.1.2 Floating support structures
    7.2 Support structure design
        7.2.1 Initial design
        7.2.2 Loads and load effects
        7.2.3 Short-term and long-term design analysis
        7.2.4 Design standards, guidelines, and other considerations
    References
8 Electrical power transmission and grid integration
    8.1 Introduction
    8.2 Implications of the grid-side converter topology on the grid integration of MECs
    8.3 Impact of MECs’ integration into power distribution systems
        8.3.1 Power quality issues in marine energy installations
        8.3.2 System impact of marine energy installations
        8.3.3 Case study
    8.4 Impact of MECs’ integration into power transmission systems
        8.4.1 Additional ancillary services that can be provided by marine energy installations
        8.4.2 Transmission technologies
        8.4.3 Case study
        8.4.4 Hybrid HVAC/DC systems and expansion planning
    References
9 Offshore energy storage
    9.1 Underwater compressed air energy storage
        9.1.1 How much exergy is stored per unit volume of air containment
        9.1.2 Corrections for air density and non-ideal gas behaviour
        9.1.3 Structural capacity and its relevance to energy storage
        9.1.4 Exergy versus structural capacity for underwater containments
        9.1.5 The air ducts
        9.1.6 Using thermal storage in conjunction with air storage
        9.1.7 An example system design
        9.1.8 Sites available for UWCAES
    9.2 Offshore pumped hydro
        9.2.1 Exergy storage density for UWPH
        9.2.2 Key distinctions between UWPH and UWCAES
        9.2.3 The EC2SC ratio for UWPH
    9.3 Buoyancy energy storage systems
    9.4 Offshore thermal energy storage systems
    9.5 Other concepts
    9.6 Integrating offshore energy storage with generation
    References
10 Multipurpose platforms
    10.1 Introduction
        10.1.1 Context
        10.1.2 Why multipurpose platforms?
    10.2 Multipurpose platform projects and concepts
        10.2.1 EU projects
    10.3 Design and analysis of multipurpose platforms
        10.3.1 Multidisciplinary design methodology
        10.3.2 Resource assessment: combined wind-wave resources
        10.3.3 Modelling and analysis
    10.4 Conclusions
    References
11 Installation, operation and maintenance of offshore renewables
    11.1 Introduction
        11.1.1 Impact of installation, operation and maintenance activities in offshore renewable systems
        11.1.2 Functional decomposition of offshore renewable systems
        11.1.3 Concepts of reliability and failure analysis
    11.2 Life cycle activities for offshore energy systems
        11.2.1 Installation phase
        11.2.2 Operation and maintenance phase
        11.2.3 Decommissioning phase
        11.2.4 Vessels and equipment
    11.3 Planning the operations
        11.3.1 Strategies for planning the operations
        11.3.2 Weather windows
        11.3.3 Estimation of the delay time
        11.3.4 Offshore standards and technical recommendations for operations
    11.4 Economic modelling of installation, operation and maintenance
    References
12 Challenges and future research
    12.1 Challenge one – proving it works
    12.2 Challenge two – keeping it working
    12.3 Challenge three – technical improvements
        12.3.1 Servicing
        12.3.2 Access
        12.3.3 Data
        12.3.4 Materials
    12.4 Challenge four – environmental acceptability
    12.5 Challenge five – social acceptability
    12.6 Challenge six – making it work commercially
    12.7 Challenge seven – getting the price down
    12.8 Challenge eight – public support required
        12.8.1 Financing arrays
        12.8.2 Market pull
    12.9 Challenge nine – market development
    12.10 Challenge ten – making it happen
    References
Index