barrage or what?
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Barrage or What?. Engineering Options. Prof Colin Taylor CEng FICE Professor of Earthquake Engineering Head, Department of Civil Engineering [email protected]. The technical options. Barrage Lagoon Tidal reef Tidal fence Tidal stream. - PowerPoint PPT PresentationTRANSCRIPT
Barrage or What?Engineering Options
Prof Colin Taylor CEng FICEProfessor of Earthquake EngineeringHead, Department of Civil Engineering
The technical options
• Barrage• Lagoon• Tidal reef• Tidal fence• Tidal stream
Source: Marc Paish, Severn Tidal Fence Group
Barrage
Barrage turbine
Source: Roger Falconer
Tidal lagoon
Source: University of Colorado
Fleming lagoon flow computation
Filling Discharging
2 2.5 3 3.5 4 4.5 5 5.5 6
2 m/s
Water level (m)
Flood
Frame 001 01 Sep 2008 Hydrodynamic Results in Nodes
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
2 m/s
Water level (m)
Ebb
Frame 001 01 Sep 2008 Hydrodynamic Results in Nodes
Source: Roger Falconer
Evans tidal reef
Source: Evans Engineering
Evans tidal reef
Low-head turbine for reef
Source: Rod Rainey, Atkins
Tidal fence
Source: Marc Paish, Severn Tidal Fence Group
Tidal stream
Source: DeltaStream Turbines
Source: Swanturbines
Short listed options
Severn Tidal Fence Group
Barrage issues
• Significant environmental impacts
• Reduction of water levels and tidal range
• Loss of inter-tidal habitats • Impacts on bird and fish
populations in the Severn• Inhibits port traffic • Protection from effects of
storm surges, sea level rise• Reduced turbidity• Established technology
La Rance, France
Lagoon issues
• Significant reduction in tidal range within the impounded area
• Loss of inter-tidal habitats• Other environmental effects
are similar to smaller barrages • Less impacts on fish and
navigation as not a full a barrier across the estuary
• Enclosure construction uncertain (e.g. embankment, caissons, innovative modular concrete/earth units?)
• Longer than barrage
Reef issues
• Unproven technology• Long development
period• Less loss of tidal
range• Lower efficiency?• Inhibits shipping
Source: Evans Engineering
Fence issues
• Unproven technology• Long development period• Less loss of tidal range• Lower efficiency?• Less impact on shipping
(but vulnerable to ship impact?)
Source: Marc Paish, Severn Tidal Fence Group
Cost comparisons
Source DECC Analysis of Options report