Seven Seas Vision Helping to make things happen at the speed of light...

We are only four years away from the centenary of what we believe is the first published reference to a tidal power barrage in the Severn Estuary.

This is not to be confused with earlier talk of railway crossings on embankments, at a time when electricity was still a gleam in the scientific eye and was certainly not the all-pervading society-determining facility which it has so quickly become. Where we would be tomorrow if electricity was to be taken away today can presumably be left to fantasy, though there have been moments over the past few decades when the lights have gone out, albeit not for long.

It is this fear that is driving governments in European and other countries to back off the extraordinary dependence on imports which we have, perhaps unconsciously, come to regard as a right - until disruptions to supplies prompt serious reflection on Gt. Britain’s energy policy.

The UK literally seems to blow hot and cold on this with very disturbing frequency. Like terrorist attacks and traffic jams, they dominate the news when they happen but all too soon routine complacency returns.

In the energy sector, all is not, of course, simply stop-go. Concern about carbon emissions from thermal power stations is increasingly affecting development policy, not least in respect of the case for re-focussing on nuclear power stations. This international industry carries huge political and financial support, as witnessed by the diversity of project sources and pressures now bidding for development opportunities in the UK and around the world particularly China presently building coal fired power stations at the rate of 2 a week. 70% of the world’s light bulbs are now made in China.

In its own way the renewable energy industry (it has now long been robust enough to warrant that description) is also truly international, politically strong and increasingly economically competitive as it gets to grips with its particular problems, such as the availability, both politically and economically, of feed-stocks for biomass-based power stations and commercially-proven technology for marine-energy driven installations - the latter with just one exception.

Tidal power based on the construction of a barrage in a high tide range estuary calls for the same power-generating technology as has been around in the hydro-electric sector since the 19th Century, and which was, of course, the motivation for the 1911 Severn Barrage proposal. With the passage of time, the 'hydro' industry, which can certainly claim to be both an industry and truly international, has come to dominate the supply of electrical power to those many countries which are able to call upon the appropriate natural resources. Norway remains a leader in this respect whereas others like France and Germany, which in earlier times included an element of ‘hydro’ dependence, have long had to look elsewhere to deal with the growing demands which changed the face of the electricity sector through the 20th Century. The UK's position is, of course, the same in this respect, though Wales had and still has the potential to remain more dependent on this source.

The Severn Barrage returned as a potentially key power-station player in 1965, largely because the French were at that time, by calling upon their prowess in hydro-technology, constructing the Rance tidal power barrage on the North Coast of Brittany, close to St. Malo. This project, which with 24 turbines not only has sufficient generating capacity to make a real contribution to supplies but is also large enough to be regarded as a proper power station, has functioned immensely well from the outset. The few technical problems which have occurred were resolved without significant loss of generation and can be attributed to the learning curve - the simple fact that the machines operating today are those which were installed more than 40 years ago - in seawater - is surely evidence of the robustness of what the French have achieved. Small wonder that others have sought to emulate their achievements, yet only South Korea has moved to construct an electrically larger scheme. Use of the construction technique based on floated-in caissons is favoured, akin to the way in which offshore oil and gas platforms are now built and which resembles giant Lego units, these having been built in Scotland and elsewhere and towed into position before being sunk onto prepared foundations. Unlike the much longer Zuider Zee barrage built by the Dutch in the 1930s, this technique would largely remove the effect of the construction operation from the local community. Barrage construction, which at today’s prices would cost in the region of £15 (?) billion, will take 5-6 years to complete, during which time many of the turbines will be installed and thereafter used to good effect whilst the remainder are supplied and commissioned.

In a recent talk which I, Tom Shaw, gave about the Severn Barrage I commented about the lack of landscape intrusion of the Rance Barrage - to us it does after all appear as only an embankment across the Rance Estuary, all of the power-generating action necessarily being below sea level, like any other hydro-power scheme. As a result, as I know from stories which have been told, it is not at all difficult to drive over the barrage on its dual-carriageway road without realising what is going on beneath your wheels. After all, it is not unusual to be uninformed about the services which lie everywhere below the tarmac. At that point, the Chairman for the meeting I was addressing spoke up, saying that he had gone to the Rance Estuary to see the barrage, and it was not until he had driven over it and was well beyond it, still looking for it, that he realised his mistake!

The Rance Barrage epitomises much that would apply to the consequences of a Severn and all other barrages. Estuaries are a focus for society, some more so than others for geographical reasons. None in the world offer the scale of power generating opportunity from an estuary which has such a developed community infrastructure as that of the Severn. For its smaller size, the Rance comes close, so we can learn, indeed we already have learnt, much from its central presence to the communities which lie about it and the tourism which passes over and through it (by boat).

2007 brings another Government-driven study of the Severn Barrage. The first reported in 1933, the second in 1945, the third in 1980, the fourth in 1989, the fifth in 2002 - and now the next. The common thread between these is that the technology is in place - although a lot of hardware would be needed, no-one either has or is saying that it cannot be built. The French have added enormous confidence to predicting its annual energy potential, to which we have added important twists to identify how we might best use it 15 years hence and thereafter in a world which, on the basis of recent events, is unlikely to be as we have it today.

Central Government recently announced that the UK's renewable energy sources now provide about 4.6% of our electricity requirements, mainly from long-established hydro schemes and recently constructed wind turbines. The Severn Barrage would eclipse all of that. In simple energy terms it would meet all of Wales' present annual demand for electricity, whilst providing a stout defence against the risk of flooding which sea level rise will only accentuate, it will assist land and marine transport, boost recreation, add greatly to land values, etc - all as evidenced at Rance. One can note here that the lagoon schemes which have been proposed would not help with sea defences nor provide any of the other peripheral benefits of the barrage. Furthermore model studies have shown that lagoons would be subject to silting up over a relatively short period leading to the need for regular dredging.

And if one is concerned at what is said in some negative quarters about its environmental implications, that's even more reason for giving Rance priority focus. EU legislation is not intended to be as holy as those looking for excuses maintain - witness the thrust of the Water Framework Directive to which Europe, as a whole, is now constructively gearing its thinking about use of the water environment.

Lastly with Sea Levels predicted to rise by 5 – 6 meters in the next (20 to 50 years) the shape of Great Britain will change dramatically as will available new building land become ever more costly to acquire. Additionally, the UK’s population will possibly increase by around 20 million. The Severn Seas Barrage Group suggest that wasting time is no longer an option. We shall also be able to predict to annual energy output of the Severn Barrage for the first 100 years!

Dr Tom Shaw
David Mappin

Co-Founders of the Severn Barrage Group in 1977
Reformed as the Severn Seas Barrage Group in 2007.