A part of BMT in Energy and Environment Foundations and Moorings for Tidal Stream Systems Client: The Carbon Trust Report no.: L.CAR.002W Date: September 2009 Confidential Foundations and Moorings for The Carbon Trust Tidal Stream Systems Report Title Foundations and Moorings for Tidal Stream Systems Client The Carbon Trust BMT Cordah Report No: L.CAR.002W Status and Version: Public draft Date of Release: September 2009 (Print Date Monday, 21 September 2009 at 12:39 PM) Terms: Name Signature Date Michael Starling Authors 21st September 2009 Alex Scott Approved by Richard Parkinson BMT Cordah Limited, 4th Floor, Holland House, 1 – 4 Bury Street, London EC3A 5AW Tel. +44 (0)20 7015 0300 Fax +44 (0)20 7015 0344 Email: [email protected] Website: www.bmtrenewables.com BMT Cordah Limited 1 September 2009 Foundations and Moorings for The Carbon Trust Tidal Stream Systems Document log Version Date Summary of changes Author Pre-issue 14 th October 2008 Skeleton Michael Starling 01 4th December 2008 First Issue Michael Starling 02 2nd January 2009 Second issue following review Michael Starling meeting on 4 th December 2008 03 8th June 2009 Third issue following contract Michael Starling extension 03a 24 th July 2009 Update with responses to Entech Michael Starling comments Public 21 st September 2009 Edited to be basis of the carbon trust Michael Starling Draft public version of the report BMT Cordah Limited 2 September 2009 Foundations and Moorings for The Carbon Trust Tidal Stream Systems CONTENTS 1 INTRODUCTION..................................................................................................................8 1.1 About the Report 8 1.2 Overview of the Report 8 2 OVERVIEW OF TIDAL STREAM DEVICES ....................................................................10 2.1 Sources of Information 10 2.2 Characteristics that affect the Foundations and Moorings 10 2.3 Tidal Stream Devices 10 2.4 Conclusions on Tidal Stream Devices 15 3 OVERVIEW OF TYPICAL TIDAL STREAM DEVICE LOCATIONS ..............................16 3.1 Relative Difficulty of Locations 16 3.2 Selection of Environmental Parameters that Drive Difficulty 16 3.3 Classification System for Environmental Parameters 18 3.4 Relative Importance of Environmental Parameters 22 3.5 Selection of Favoured Locations 23 3.6 Classification of the Favoured Locations 24 3.7 Relative Difficulty of Favoured Locations 27 3.8 Conclusions on Location Difficulty 28 4 FOUNDATIONS AND MOORING REQUIREMENT SPECIFICATION ...........................31 4.1 Success Criteria 31 4.2 Life 31 4.3 Loadings 32 4.4 Installation 34 4.5 Operations and Maintenance 34 4.6 Conclusions on Requirement Specification 35 5 REVIEW OF FOUNDATION AND MOORING METHODS ..............................................36 5.1 Characteristics that affect the suitability of a Foundation or Mooring 36 5.2 Potential Foundations and Moorings 36 5.3 Further Information on Foundation Types 40 5.4 Further Information on Moorings Types 44 5.5 Maintenance of Foundations and Moorings 47 5.6 Conclusions on Foundation and Mooring Methods 49 6 INDICATIVE INSTALLATION COSTS .............................................................................51 6.1 General 51 6.2 Cost Bands 52 6.3 Installation Vessel Costs 53 BMT Cordah Limited 3 September 2009 Foundations and Moorings for The Carbon Trust Tidal Stream Systems 6.4 Base Case Costs 56 6.5 Commentary on the Cost Adjustment Factors 59 6.6 Conclusions on Installation Costs 61 7 COMPARATIVE COSTS OF FOUNDATION AND MOORINGS INSTALLATION .........63 7.1 Basis of the Costing 63 7.2 Summary of the Findings 63 7.3 Limitations of the Cost Modelling 65 8 CONCLUSIONS.................................................................................................................66 8.1 Integration of Foundation Design with Device Design 66 8.2 Foundation Design - Need to use tried and tested designs 66 8.3 Mooring Design - Need to demonstrate feasibility 66 8.4 Installation of Single Devices and Series Installation 66 8.5 Installation Vessels - Need to investigate the “ideal” vessels 67 8.6 Maintainability - Need to design for ease of maintainability 67 9 RECOMMENDED ARRAS FOR FURTHER RESEARCH ...............................................68 9.1 Suggested Research to Reduce Risk 68 9.2 Suggested Research to Investigate Opportunities 69 9.3 Research Programme Participants 70 10 OBSTACLES ON THE ROUTE TO MARKET .................................................................71 10.1 Routes to Market Template 71 10.2 Conclusions and Directed Research 71 11 ANNEX A - SCOPE AND PURPOSE OF A REQUIREMENT SPECIFICATION............74 11.1 Phases of Development 74 11.2 Phases of an Installation 75 11.3 Installation Cost Drivers 76 11.4 Phases of Operation 76 11.5 Factors Affecting Operations 77 12 ANNEX B - EXAMPLE ENVIRONMENT IN THE PENTLAND FIRTH ............................78 12.1 Difficulty of the Location 78 12.2 Geology of the Location 81 12.3 Ecology and Marine Life at the Location 82 12.4 Marine Growth On Foundations and Moorings 84 12.5 Anti-Fouling Solutions 89 12.6 Tidal Current Converter 90 13 ANNEX C – ADDITIONAL INFORMATION ON COST MODELLING.............................91 13.1 Cost Variability 91 13.2 Technical Parameters used in the Cost Model 92 BMT Cordah Limited 4 September 2009 Foundations and Moorings for The Carbon Trust Tidal Stream Systems 13.3 Technical Parameters used in the Cost Model 93 TABLES Table 1 Tidal Devices and their Moorings 14 Table 2 Tidal Currents - Classification of Tidal Speed 18 Table 3 Tidal Currents - Classification of Flow Conditions 18 Table 4 Tidal Currents - Classification of Variation Across Site 18 Table 5 Tidal Currents - Classification of Data Uncertainty 19 Table 6 Water Depths - Classification of Depth at Lowest Astronomical Tide 19 Table 7 Water Depths - Classification of Tidal Range 19 Table 8 Weather Exposure - Classification of Survivability Extremes 20 Table 9 Weather Exposure - Classification of Wave and Wind Windows for Installation 20 Table 10 Bathymetry - Classification of Seabed 21 Table 11 Bathymetry - Classification of Marine Hazards 21 Table 12 Relative Importance of Classifications 22 Table 13 Classification of Favoured Locations 26 Table 14 Relative Difficulty of Favoured Locations 27 Table 15 Potential Foundations for Tidal Stream Devices 38 Table 16 Potential Moorings for Tidal Stream Devices 39 Table 17 Installation Cost Bands - Lump Sum Base Costs 52 Table 18 Installation Cost Bands - Day Rate Base Costs 52 Table 19 Installation Cost Bands - Cost Adjustment Factors 52 Table 20 Installation Vessels and their Costs 55 Table 21 Indicative Bases Costs and Cost Adjustment Factors of Installing a Foundation 58 BMT Cordah Limited 5 September 2009 Foundations and Moorings for The Carbon Trust Tidal Stream Systems Table 22 Technology Route to Market 72 Table 23 Project Route to Market 73 Table 24 Density of Marine Growth 85 Table 25 Tidal Current Converter (m/s <-> knots) 90 FIGURES Figure 1 Normalised Installation Costs 64 Figure 2 Technology Route to Market 71 Figure 3 Project Route to Market 71 Figure 4 Circling in on a Design Solution 74 Figure 5 Phases of a Marine Development 75 Figure 6 Phases of a Marine Installation 75 Figure 7 Installation Cost Drivers 76 Figure 8 Phases of Marine Operations 76 Figure 9 Operations Cost Drivers 77 Figure 10 Tidal Currents Cycles in the Pentland Firth 78 Figure 11 Tidal Currents Cycles in the Pentland Firth - Spring Tide 79 Figure 12 Tidal Currents Cycles in the Pentland Firth - Neap Tide 79 Figure 13 Normalised Installation Cost Variability - Foundations 91 Figure 14 Normalised Installation Cost Variability - Moorings 91 Figure 15 Technical Parameters - Foundations 92 Figure 16 Technical Parameters - Moorings 92 Figure 17 Cost Parameters - Foundations 93 Figure 18 Cost Parameters - Moorings 93 BMT Cordah Limited 6 September 2009 Foundations and Moorings for The Carbon Trust Tidal Stream Systems MAPS Map 1 Map of Favoured Locations 23 BMT Cordah Limited 7 September 2009 Foundations and Moorings for The Carbon Trust Tidal Stream Systems 1 INTRODUCTION 1.1 About the Report The tidal stream energy system developers share a common challenge. Each device needs to be held on station in a tidal flow in a practical and cost-effective way. The foundations or mooring systems required can form a significant part of the life-cycle cost of the system since they contribute to the capital cost and the ease of installation and maintenance of the device. There are many methods of solving this problem ranging from well-established solutions to new and innovative solutions. This report is a review of the state of the art in foundation and mooring systems and their applicability to tidal stream systems”. It has been produced by BMT Fleet Technology, BMT Cordah and Mojo Maritime and much of the information derives from the knowledge of BMT and Mojo Maritime. It was produced by the following team. o Michael Starling, of BMT Fleet Technology, for his expertise in renewable energy. o Alex Scott, of Mojo Maritime Ltd, for his expertise in sub sea construction and installation, foundations and moorings; o Richard Parkinson, of Mojo Maritime Ltd, for his expertise in offshore construction, moorings and installation of tidal and wave energy devices; o Paul Bowerman, of BMT Cordah, for his expertise on marine mapping and wave and tidal conditions. The project was managed by Michael Starling and was supervised, on behalf of the Carbon Trust, by Richard Boud. 1.2 Overview of the Report The report is made up of the