2. 2
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
Tidal Power from the Severn
4. 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
6. 6
Barrage Layout (1989 Report)
• 216 Turbines,
40MW each,
8640MW total
• 166 Sluices
35,000m2
• Ship Locks
• Small Locks
• Public Road
7. 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. 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. 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. 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
12. 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. 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
15. 15
Caisson
Construction Sites
• 1989 report identified
potential UK sites shown
•Potential Sites in Europe
• Project and Employment
Benefits of using many
Sites
23. 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
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 2007. This will enable Barrage closure and hence first power to be generated in 2015, with full commissioning by the end of 2016.