Joule Project JIRP106/03 Oct 2006 – Dec 2008 Tapping the Tidal Power Potential of the Eastern Irish Sea FINAL REPORT March 2009 Richard Burrows, Ian Walkington, Nick Yates, Terry Hedges, Daoyi Chen, Ming Li, Jianguo Zhou Department of Engineering, University of Liverpool, Liverpool L69 3GQ Judith Wolf, Roger Proctor, Jason Holt Proudman Oceanographic Laboratory, Liverpool L3 5DA David Prandle Consultant www.liv.ac.uk/engdept/tidalpower CONTENTS Page LIST OF FIGURES iv LIST OF TABLES ix ACKNOWLEDGEMENTS (and Definition) xiii EXECUTIVE SUMMARY ES.1 1. INTRODUCTION 1.1 1.1 Terms of reference 1.1 1.2 Background 1.1 1.3 Project aims and objectives 1.3 2. PRELIMINARY STUDIES 2.1 2.1 Initial appraisals of barrage potential based on Prandle’s approach 2.1 2.2 Reassessment of the 1980s Department of Energy barrage scheme 2.2 energy estimates 2.2.1 Conjuctive operation 2.3 3. ENERGY FROM MAJOR BARRAGE SCHEMES (0-D MODELLING) 3.1 3.1 0-D modelling context 3.1 3.2 Dee Estuary and Dee-Wirral Lagoon 3.2 3.2.1 Initial appraisal (ebb generation only) 3.3 3.2.2 Investigating different operating modes 3.5 3.2.2.1 Effect of pumping 3.6 3.2.3 Turbine conditioning 3.7 3.2.3.1 Changing generator capacity 3.7 3.2.3.2 Increasing turbine diameter 3.8 3.2.3.3 Conclusion 3.8 3.2.4 Increasing installed turbine capacity and cost implications arising 3.10 3.2.4.1 Comment and discussion 3.12 3.2.5 Increasing installed sluice capacity and cost implications arising 3.13 3.2.6 Dee Outer Barrage (Dee-Wirral Lagoon) 3.14 3.2.7 Dee Offshore Lagoon 3.15 3.3 Mersey Estuary 3.16 3.3.1 Initial appraisal (ebb generation only) 3.17 3.3.2 Investigating different operating modes 3.17 3.3.2.1 Effect of pumping 3.18 3.3.3 Turbine conditioning 3.19 3.3.3.1 Changing generator capacity 3.19 3.3.4 Increasing installed turbine capacity and cost implications arising 3.21 3.3.4.1 Effect on generation window 3.22 3.3.5 Increasing installed sluice capacity and cost implications arising 3.23 3.3.6 Intertidal area 3.24 3.4 Ribble Estuary 3.28 3.5 Morecambe Bay 3.29 3.5.1 Initial appraisal (ebb generation only) 3.31 3.5.2 Investigating different operating modes 3.31 3.5.2.1 Effect of pumping 3.32 3.5.3 Turbine conditioning 3.33 3.5.3.1 Changing generator capacity 3.33 i 3.5.4 Increasing installed turbine capacity and cost implications arising 3.35 3.5.5 Increasing installed sluice capacity and cost implications arising 3.36 3.6 Solway Firth 3.36 3.6.1 Initial appraisal (ebb generation only) 3.38 3.6.2 Investigating different operating modes 3.38 3.6.2.1 Effect of pumping 3.39 3.6.3 Turbine conditioning 3.40 3.6.3.1 Changing generator capacity 3.40 3.6.4 Increasing installed turbine capacity and cost implications arising 3.42 3.6.5 Increasing installed sluice capacity and cost implications arising 3.43 3.6.6 Conclusion 3.44 4. CONJUNCTIVE (MULTI-SCHEME) ENERGY CAPTURE (2-D 4.1 MODELLING) 4.1 Introduction 4.1 4.2 Present climate scenario 4.3 4.2.1 Base configuration (1xDoEn) 4.3 4.2.1.1 One-way (ebb) mode operation 4.3 4.2.1.2 Two-way (dual) mode operation 4.5 4.2.2 Tidal stream turbine farm energy capture 4.7 4.2.3 Enhanced energy capture from tripling turbine capacity (3xDoEn) 4.9 4.2.3.1 One-way (ebb) mode operation 4.9 4.2.3.2 Two-way (dual) mode operation 4.11 4.2.4 Combined tidal range (1xDoEn barrages, ebb mode) and tidal stream 4.13 extraction 4.2.4.1 Tidal range 4.13 4.2.4.2 Tidal stream 4.14 4.2.5 Summary 4.15 4.3 Future climate scenario 4.16 4.3.1 Tidal range 4.17 4.3.1.1 One-way (ebb) mode operation (1xDoEn) 4.17 4.3.1.2 Two-way (dual) mode operation (3xDoEn) 4.18 4.3.2 Tidal stream 4.20 4.3.3 Combined tidal range (3xDoEn barrages, dual mode) and tidal stream 4.21 extraction 4.3.3.1 Tidal range 4.21 4.3.3.2 Tidal stream 4.21 4.3.4 Summary 4.22 5. ENVIRONMENTAL IMPLICATIONS 5.1 5.1 Introduction 5.1 5.1.1 Generic impacts of tidal power schemes 5.2 5.1.1.1 Physical changes 5.2 5.1.1.2 Environmental and ecological impacts 5.2 5.1.1.3 Human, economic, aesthetic and amenity impacts 5.3 5.1.2 Modelling studies: far-field effects 5.3 5.2 Present hydrodynamics in the Irish Sea (base run) 5.4 5.3 Impact of changes in tide-induced circulation 5.6 5.3.1 One-way (ebb) mode operation (1xDoEn) 5.6 5.3.2 Two-way (dual) mode operation (3xDoEn) 5.8 5.3.3 Environmental implications 5.10 5.4 Impacts on the estuarial waters and intertidal regime 5.11 5.4.1 Introduction 5.11 5.4.2 Case study for the Mersey Estuary 5.13 ii 5.4.2.1 2-D modelling 5.14 5.4.2.2 Environmental implications 5.16 5.5 Impact on sediment regime and induced morphological changes 5.17 5.6 Water quality issues from reduced exchange and sediment 5.22 disturbance 5.6.1 Surface water quality 5.22 5.6.2 Contaminated sediments 5.23 5.7 Flood defence 5.25 5.7.1 Flood risk in the estuaries and protection offered by barrages 5.25 5.7.2 Global warming and coastal vulnerability 5.28 5.7.3 Conclusion 5.28 6. CONCLUSIONS AND RECOMMENDATIONS 6.1 6.1 Conclusions 6.1 6.2 Recommendations 6.2 7. REFERENCES AND BIBLIOGRAPHY 7.1 APPENDICES 1. A.1 A.1.1 The research team A.1.2 House of Commons evidence A.1.3 Tidal stream energy extraction from estuaries 2. A.2 A.2.1 Theoretical background to energy computations (0-D modelling) A.2.2 Implication of entry and exit losses in turbine conduits A.2.3 Validation of Turgency/Generation Matlab computational routines A.2.4 Preliminary studies – potential from barrages on major UK estuaries A.2.5 Constructional aspects 3. A.3 A.3.1 Barrage lines, cross sections and bathymetries A.3.2 Energy computation spreadsheets A.3.3 Costing calculations 4. A.4 A.4.1 ADCIRC background A.4.2 Barrage operation in ADCIRC A.4.3 Tidal stream farms in ADCIRC A.4.4 Validation of simulation grid iii LIST OF FIGURES Page Figure 1: Different modes of operation of a tidal barrage. ES.2 Figure 2: The 0-D modelling interface: example for Dee scheme. ES.3 Figure 3: ADCIRC tidal modelling domain showing bathymetry and ES.3 unstructured grid (North West barrages shown inset). Figure 4: Illustration of power pulses and basin levels for schemes on the ES.5 Dee. Figure 5: Intertidal area retained in the Mersey. ES.6 Figure 6: 1xDoEn schemes in ebb-mode operation (spring output shown ES.7 inset). Figure 7: 1xDoEn schemes in dual-mode operation (spring output shown ES.8 inset). Figure 1.3.1: Schematic illustration of potential barrages initially envisaged. 1.3 Figure 2.2.1.1: Power output of all barrages with maximum generation window 2.4 (preliminary studies). Figure 2.2.1.2: Power output of all barrages during spring tides with maximum 2.4 generation window (preliminary studies). Figure 2.2.1.3: Power output of all barrages during neap tides with maximum 2.5 generation window (preliminary studies). Figure 2.2.1.4: Power output of all barrages for maximum energy generation 2.5 (preliminary studies). Figure 2.2.1.5: Power output of all barrages during spring tides for maximum 2.6 energy generation (preliminary studies). Figure 2.2.1.6: Power output of all barrages during neap tides for maximum 2.6 energy generation (preliminary studies). Figure 3.1.1: Screen image showing: top – turbine performance characteristics; 3.1 middle – tidal (green) and basin (blue) level variations; and bottom – power outputs. Figure 3.2.1: Sketch showing the location of a Dee Barrage. 3.2 Figure 3.2.2: Dee basin area (km2) as a function of water level (mAOD). 3.3 Figure 3.2.1.1: Illustration of the ebb generating cycle. 3.4 Figure 3.2.1.2: Effect of delays on annual ebb energy output from Dee Barrage 3.4 (initial appraisal). Figure 3.2.2.1: Dee Barrage water levels for different operating modes (samples 3.6 from the spring tidal phase; external tide level in green, basin water level in blue). Figure 3.2.3.3.1: Dee Barrage water levels and power output for 6m diameter 3.9 turbines; ebb mode. Figure 3.2.3.3.2: Dee Barrage water levels and power output for 8m diameter 3.9 turbines; ebb mode. Figure 3.2.4.1: Dee Barrage dual mode operation with 80 8m x 10MW turbines. 3.10 Figure 3.2.4.2: Annual energy output from Dee Barrage operating in ebb and dual 3.11 modes as a function of number of turbines.