Northwest tidal power to rival Severn Barrage

Four major tidal barriers in the north west of England could supply 5% of the present UK electricity demand, rivalling the Severn barrage, research has shown.

Conjunctive operation of barrages across the Solway Firth, Morecambe Bay and the Mersey and Dee estuaries, and possibly the Ribble, could put the North West tidal resource on a par with the Severn Estuary, say researchers at the University of Liverpool, who carried out the two year study ‘Tapping the Tidal Power Potential of the Eastern Irish Sea’.
The renewable energy captured could reliably meet about half of the North West’s daily electricity need, over a 120-year operational life, whilst providing:-

• substantial estuarial sea defence and flood risk protection extending up-river beyond tidal limits
• road/rail crossings reducing travel distances and so encouraging socio-economic development
• substantial employment during the design and construction phases
• tourism interest and greater recreational opportunity;

Outline costing studies suggest that with governmental funding at favourable discount rates (~3.5%), these developments should be competitive against alternative renewable sources.

The most attractive locations for harnessing tidal power are estuaries with a high tidal range for barrages and other areas with large tidal currents (e.g. straits and headlands) for free-standing tidal stream turbines.

Source: The New Civil Engineer

Tidal barrages delay the natural motion of the estuary flows as sea level changes: holding back the release of high tide out of the inner estuary basin, for so-called ‘ebb-flow’ electricity generation when water level difference across the barrage is sufficient for turbine operation; deferring entry of water into the estuary as tide levels rise ‘flood-flow’ generation; or ’two-way (dual) mode’, a combination of both). Each mode permits generation for typically between 8 and 11 hours a day. The North West tidal development and the Severn barrage would be complementary in respect to the timings of their twice-daily pulsed inputs to the electricity grid