First proposed in 1840, the scheme really gained momentum in 1981 when a group of contractors, known as the Severn Tidal Power Group(STPG), carried out engineering and environmental studies into a 16km barrage spanning the Severn between Cardiff and Weston-Super-Mare.
STPG's findings were published jointly with the Government in 1989, but subsequently fell from consideration following privatisation of the electricity industry in 1990.
Harnessing the massive renewable energy resource that is the tidal range of the Severn Estuary, at 14m the second largest in the world, has again hit the political radar thanks tp the combined forces of European renewable energy targets and rocketing oil and gas prices.
In September 2007, Business secretary John Hutton announced that the Government would be running a two-year feasibility study into tidal power in the Severn Estuary, exploring a number of technologies including several barrage proposals.
Two contracts have so far been awarded under the feasibility study: a consortium led by consultant Parsons Brinckerhoff is managing a Strategic Environmental Assessment of all the options being considered; an investigation into the funding of the various tidal schemes is being carried out by PriceWaterhouseCoopers.
Apart from the substantial upfront cost of a barrage across the Severn estuary - the Cardiff-Weston alignment is estimated at £14bn - the main objection to this renewable energy scheme that could meet 5% of the UK's electricity demand is, ironically, an environmental one.