The Severn Barrage may be dead as a project, but Tidal Lagoon Power, the development company behind the proposed Swansea Bay Tidal Lagoon in South Wales, says it has successfully completed two-dimensional physical model testing.
With planning applications due to be submitted shortly, a section of bund wall has been constructed to scale in a 1.2 metre deep flume at HR Wallingford in Oxfordshire.
Tests included the stability of rock armour under various design conditions with different combinations of water levels and wave heights including wave overtopping and sea level rises resulting from climate change.
The impact of storm waters/surges was also measured to ensure that the final design structure is optimised for long-term stability and safety. Given the massive storms experienced this winter, this is particularly topical.
As the world’s first, man-made, energy-generating lagoon, with 240MW nominal rated capacity averaging 16 hours of generation every day, Swansea Bay Tidal Lagoon is expected to provide clean, renewable, reliable and predictable power for over 120,000 homes (enough to power 70% of Swansea Bay’s annual domestic electricity use) for over 120 years. It could be connected to the National Grid by 2018.
The development will, if built, comprise a breakwater wall, concrete turbine housing similar to those found in many maritime structures, sluices and hydro turbines (whose reliability has been established for 50 years) as well as a visitor centre and associated onshore amenities.
The hydro turbines will be installed in a single section of the outer reaches of the breakwater wall, through which estuarine water can flow four times daily to generate power.
Although the lagoon is the first of its kind, all component parts of the project have been proven elsewhere in the world, keeping technology risk low, insists the project’s developer.
Engineering director Ton Fijen said of progress: “Physical modelling remains the most reliable way to test conditions and that is why we are working with HR Wallingford as one of the world’s leading providers of analysis, advice and support for engineering and environmental hydraulics and the management of water.”
The Severn Estuary is subjected to the second highest tidal range in the world and, within this, Swansea Bay benefits from an average tidal range during spring tides of 8.5m.
This tidal range offers significant potential for the extraction of renewable energy through the construction of tidal lagoons and is an exciting opportunity for Wales and the UK with the potential for over 10,000MW of power from a series of five coastal tidal lagoons.”
The only other tidal barrage system in Europe is in France at La Rance, Brittany.
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