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 (EP ) was the first major study Tripartite study (EP ) defined the present scheme Could produce power by 2017 if progressed soon

3. Location: Downstream of Cardiff to Weston-super-Mare 16 km length
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, MW 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 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. Cost – Price relationship1 2 3 4 5 6 7 8 9 10
Cost
ILEX April
2005 spot
market
forecast
Actual
Price
7 Dec 05
Tax
Equity Return
Transmission Opex
Transmission Capex
Barrage Opex
Barrage Capex
ROC recycle
ROC buyout
Wholesale electricity price
p/kWh
April 2005 money

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

20. Flow Patterns with Barrage

21. Construction Sequence
(1989 Report)

22. Areas at Risk from Flooding

23. 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

24. Outline Programme for Implementation
If Government authorises a re-appraisal soon, and this demonstrates that the Project is viable having regard to the changed circumstances, first power could be available in 2015.
The key to the further development of the Severn Barrage is recognition of the potential long term benefits of the Project in the forthcoming Energy White Paper.
Our recent study makes it clear that Government would need to be a key part in the development and promotion of the Project. The number of parties involved across wide sectors and geography mean that only Government would be able to achieve consensus to approve the Project.
The re-appraisal will examine the organisational structure, including Government’s role, and the financing of Project implementation. These aspects of the Project were withdrawn from the 1989 studies because of privatisation of the electricity industry and have never been completed.
If Government decides that the Project has strategic value and agrees to support it, the preparation of the enabling legislation and its passage through parliament is expected to take 2 years - leading to Royal Assent for the Bill in the next Parliament around 2007.
Completion of the detailed design and Environmental Assessment are anticipated as taking a further 2 years with construction commencing around This will enable Barrage closure and hence first power to be generated in 2015, with full commissioning by the end of 2016.