HOT TOPICS

IN DEFENCE

Tom Shaw* argues the case for the controversial Severn Barrage.

We are only four years away from the centenary of 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 only a gleam in the scientific eye and not the all-pervading, society-determining facility which it has so quickly become.  Where we would be tomorrow if it was to be taken from us today is, hopefully, fantasy, though there have been moments over the past few decades when the lights have gone out.
 
It is this fear that is driving governments in European and other countries to back off from their extraordinary dependence on imports which we have, perhaps unconsciously, come to regard as a right - until disruptions to supplies prompt reflection on policy.  The UK literally seems to blow hot and cold on this with disturbing frequency. Like terrorist attacks and traffic jams, they dominate the news when they happen, before routine returns.
 
The renewable energy industry (it is robust enough to warrant that description), is also truly international, strong politically and, increasingly, competitive economically 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 one exception.
 
Tidal power, based on a barrage in a high tide range estuary, calls for the same power-generating technology that has been the lifeblood of the hydro-electric sector since the nineteenth-century, and which was, of course, the motivation for the first (1911) Severn Barrage proposal.    With the passage of time, the 'hydro' industry has come to dominate the supply of electrical power to the many countries which can call upon natural resources.   Norway remains a leader in this respect; others like France and Germany have long harnessed much of theirs in response to the ever-growing demands which changed the face of the electricity sector through the twentieth-century.  
 
The Severn Barrage returned as a potential power station player in 1965, largely because the French were then constructing the Rance tidal power barrage on the north coast of Brittany, close to St. Malo.  This project, with 24 turbines, has sufficient generating capacity to make a real contribution to supplies. It is large enough to be regarded as a proper power station and it has functioned well from the outset.   The simple fact that the machines operating today are those installed more than 40 years ago - in seawater - is stark evidence of the robustness of what the French have achieved.   Small wonder that others have sought to emulate their achievements, most recently the South Koreans.
 
Estuaries are a focus for society for geographical reasons.  But none offer the power generating opportunity and such a developed community infrastructure as the Severn, though the Rance comes close.   Hence, we can learn much from its presence to the communities which lie about it and the tourism which passes through it.
 
Last year brought another Government-driven study of the Severn Barrage.  The first dates from 1933, the second 1945, the third 1980, the fourth 1989 and the fifth in 2002.  Their common thread is that the technology is in place, and no one is saying that it cannot be built.
 
Central Government announced recently that the UK's renewable energy sources now provide 4.6 percent of our electricity requirements, mainly from long-established hydro schemes and wind turbines constructed recently.  The Severn Barrage would eclipse all of that.  It would, for example, meet all of Wales' present annual demand for electricity, whilst also providing a stout defence against the risk of flooding due to sea level rise, assisting land and marine transport, boost recreation and add greatly to land values - all as evidenced at Rance.
 
If one is concerned about its environmental implications, that is even more reason for focussing on Rance.  Scientific evidence dating from the nineteenth-century tell us what we need to know about the changes which 41 years of barrage operation have brought to an estuary which has much in common with the Severn.
 
 
*Tom Shaw of Shawater is a fellow of CIWEM.