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Barrage or What?. Engineering Options. Prof Colin Taylor CEng FICE Professor of Earthquake Engineering Head, Department of Civil Engineering colin.taylor@bristol.ac.uk. The technical options. Barrage Lagoon Tidal reef Tidal fence Tidal stream.
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Barrage or What? Engineering Options Prof Colin Taylor CEng FICE Professor of Earthquake Engineering Head, Department of Civil Engineering colin.taylor@bristol.ac.uk
The technical options • Barrage • Lagoon • Tidal reef • Tidal fence • Tidal stream Source: Marc Paish, Severn Tidal Fence Group
Barrage turbine Source: Roger Falconer
Tidal lagoon Source: University of Colorado
Fleming lagoon flow computation Source: Roger Falconer Filling Discharging
Source: Evans Engineering Evans tidal reef
Source: Rod Rainey, Atkins Low-head turbine for reef
Source: Marc Paish, Severn Tidal Fence Group Tidal fence
Source: DeltaStream Turbines Tidal stream Source: Swanturbines
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