The plans have been put forward by specialists at Strathclyde Univer­sity, who say the scheme could become reality within the next few years.

Marine architect Robert McNair and his colleague Colin MacFarlane, emeritus professor of engineering at Strathclyde, told The Herald that bold measures would be needed if Scotland was to meet its renewable energy targets and see off the threat posed by increased flooding risk in decades to come.

The structure would dominate the mouth of the Clyde, running from Greenock to the Ardmore Point, between Helensburgh and Dumbarton, with a further rail and road bridge to be added upstream.

Although similar developments have been proposed in the past, the last serious attempt at building a Clyde barrage was dismissed by the then Scottish Secretary Willie Ross in 1964, who said it would be impossible because of “technical engineering considerations”.

Advances in the past 45 years have now overcome these barriers, according to Mr McNair, and the increased risk of flooding due to climate change and rising sea levels make the barrage a more financially sound investment.

It could also aid shipping, as water depths could be controlled to allow passage of large vessels without the need to wait for favourable tides, and it could be built to incorporate a railway station for freight.

The engineers have contacted Energy Minister Jim Mather to air their proposals directly, and a spokesman for his office said the Government was keen to meet face to face to go over the scheme in more detail.

“The concept of a barrage across the Clyde is not new, yet generating clean, green energy from the river is an interesting idea and we would be happy to discuss it with Mr McNair,” he said.

Mr MacFarlane and his colleague acknowledge that the barrage would not be the cheapest way to produce electricity, but they have insisted

that it makes economic sense because of the flood protection and other environmental benefits it would bring.

The scheme would generate approximately 200GWH per year, considerably less than the Severn Barrage or the Solway Energy Gateway, but because its output could be controlled and stored relatively easily it would be a valuable addition to the less-reliable power provided by wind farms.

Mr McNair said immediate action was needed to safeguard against flooding over the next century and beyond, and that the barrage could save millions of pounds in the long run by preventing damage to property and replacing piecemeal local authority efforts to tackle the dangers.

He said: “We feel the time is right to open up debate about what we really are going to do about the major flood issues of the near, mid-term and long-term future. Severe flooding could permanently damage the estuary environment and the expense of flood prevention will eventually be overwhelming.”

Referring to previous attempts to build Clyde barrages, he added: “There is clearly sufficient evidence to change the Government’s decision of 1964.

Associated tidal flood problems will not go away and this is a combined solution for renewables, economic regeneration and flooding. This system protects people and habitat alike. I hope the SNP Scottish Government will seriously look at this concept in the very near future.”