Estuary power

Alan Black (Letters, 15 December), writes that “river estuary turbines would destroy the marine environment for hundreds of miles”. If the sea level rises, these hundreds of miles would be irrevocably changed either by erosion, or by engineering works to prevent this.

However, if the estuary is protected at the mouth by a barrage, this can be avoided and the power of the tides used for electrical generation, mimicking the present tidal ebb and flow.

He also states that “they would switch off entirely” at high and low tides. This is obviated by constructing two basins, which would allow power to be available at all times using pumped or gravity storage, called “always on” tidal power.

The Severn Barrage has been described as potentially supplying one-fifth of England’s power requirements. Tidal range in the Firth of Forth is six metres, only slightly less than the Severn. The River Tay has a greater flow than Severn and Thames together, and never dries up. We are sitting on a goldmine.

Iain WD Forde

Main Street,

Scotlandwell, Kinross-shire