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The Severn Barrage Presentation to Severn Estuary Forum 8 th June 2006 David Kerr

The Severn Barrage Presentation to Severn Estuary Forum 8 th June 2006 David Kerr Sir Robert McAlpine. Tidal Power from the Severn. Bondi study (EP46 - 1981) was the first major study Tripartite study (EP57 - 1989) defined the present scheme Could produce power by 2017 if progressed soon.

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The Severn Barrage Presentation to Severn Estuary Forum 8 th June 2006 David Kerr

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  1. The Severn Barrage Presentation to Severn Estuary Forum 8th June 2006 David Kerr Sir Robert McAlpine

  2. Tidal Power from the Severn Bondi study (EP46 - 1981) was the first major studyTripartite study (EP57 - 1989) defined the present schemeCould produce power by 2017 if progressed soon

  3. Location: • Bristol Channel/ Severn Estuary • Downstream of Cardiff to Weston-super-Mare • 16 km length

  4. Tidal Power • The Barrage impounds the tide, then the water is released through a turbine to generate electricity • Proven Technology: La Rance in France has generated tidal power reliably for over 35 years

  5. Barrage Operation

  6. Barrage Layout (1989 Report) • 216 Turbines, 40MW each, 8640MW total • 166 Sluices 35,000m2 • Ship Locks • Small Locks • Public Road

  7. Facts and Figures • Annual Output 17 TWh (5% of UK consumption) • Installed Capacity 8640 MW • Renewables Obligation: • 15% by 2015 (50-55TWh) - Barrage cannot contribute • 20% by 2020 would require a further 17TWh. Barrage could contribute all of this - if sanctioned soon • Capital Cost £8Bn 1989 > ~£14Bn 2005 – needs re-estimate • Security of supply benefit

  8. Environmental Studies 1989 • A total of 70 studies, with a budget of £2M, covering: • Hydrodynamics (tides, currents, waves) • Sediments, Salinity,Water Quality, Drainage • Ecology, Birds, Fish

  9. Main effects of the Barrage • Tide Range reduced from 14m to 7m (springs) • A smaller inter-tidal area • Reduced currents, leading to:- A large reduction in suspended sediment • Sunlight penetration through the water column • An increase in dissolved oxygen to more normal levels • A more stable seabed with more life • Expected to Result in an increase in bird species and numbers

  10. Flood protection in the Severn Estuary and Rivers • Flooding in the estuary can occur when extreme high tides coincide with storm surges • Flooding in the rivers can occur when these same sea conditions coincide also with high river flows • The water level in the basin can be controlled - • To prevent the flooding in the estuary (upstream of the barrage) • To avoid obstruction to river flow caused by high tides

  11. Use Of Barrage for Flood Protection

  12. Environmental Balance ? • Loss of the unique harsh environment • Some birds may lose habitat • Marine life and other birds will increase • Flood protection to estuary and rivers • Carbon Saving • The environmental assessment needs to be updated to account for the changes in the Estuary since the 1980’s and also the changes in legislation

  13. Transport Key Issues • Ports and Shipping • Forecast Shipping Movements • Size of Locks to suit Portbury & Avonmouth • Road and Rail • Cost-benefit of a Barrage Crossing

  14. Construction : Prefabricated Caissons

  15. Caisson Construction Sites • 1989 report identified potential UK sites shown • Potential Sites in Europe • Project and Employment Benefits of using many Sites

  16. Turbine Installation

  17. 10 9 8 Tax 7 Equity Return 6 Transmission Opex 5 Transmission Capex 4 Barrage Opex 3 Barrage Capex 2 1 0 Cost ILEX April Actual 2005 spot Price market 7 Dec 05 forecast Cost – Price relationship ROC recycle ROC buyout Wholesale electricity price p/kWh April 2005 money

  18. Conclusion The Severn Barrage should be re-examined as part of the Energy Review

  19. Flow Patterns with Barrage

  20. Construction Sequence (1989 Report)

  21. Areas at Risk from Flooding

  22. Modes of operation Ebb Generation: Preferred for most schemes Flood Generation Less usable water volume Two Way Generation No extra Energy Higher cost of Energy due to more complex turbines Energy is spread over more of the day

  23. Outline Programme for Implementation

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