1989 proposal

A Severn barrage would play in integral part in contributing to the UK’s commit to reduce greenhouse gas emissions by 2010 and beyond. Potentially providing 7% of electrical power, the barrage would also lessen the UK’s dependency on foreign political issues for energy supply. Further, a barrage would generously boost the regional economies of South Wales and North Somerset. Large numbers of temporary and permanent jobs would be created; long term tourism would also receive a welcome lift.

Additional to the obvious economic and political benefits, the environment would holistically benefit also. However, the destruction of internationally important habitat for a wide range of biota would be deemed wholly unacceptable to many powerful environmental organisations. Although their tacit approval would not be necessary, an ambivalent attitude would be a minimum requirement to prevent wholesale protestations.

1994 proposal

Modern wind turbines can be rated as high as 5MW each – an increase of over 1100% from 1994 output levels. Assuming that the number of turbines, 150, would remain the same in a modern similar proposal, the output from wind power would be approximately 1,533,998MW or 1.534TW (appendix C). Although this increased output would contribute substantially more than plant proposed in 1994, opposition to wind turbines has grown on 2 major fronts. Firstly, a growing proportion of the UK population (appendix D) appear to be becoming more vocal against the aesthetic aspect of wind farms. 150 turbines located and affecting any one scene, each turbine being 100 metres high or more, would be highly dominating. Strong objections can be predicted from locals whose view or livelihood depends on scenic beauty.

Additionally, the RSPB are currently opposing large wind farms in Shell Flat, Lancashire, and Thames Estuary, fearing that their rotating blades could adversely impact Common Scoter wintering grounds 22. With the Severn estuary harbouring several large populations of international importance (see 1989 proposal, paragraph 2.5), the RSPB is very likely to strongly oppose a large wind farm. With over 1 million members 23, the views of the RSPB carry considerable weight.

Although the sea clams would have provided the seaboard side of the barrage with protection from wave action and saline erosion 16, the additional cost of up to £13.2 million for just 13MW appears expensive. More benefit would be derived from implementing artificial reefs, at a fraction of the cost, to protect the barrage if deemed necessary 20.

It is an important fact that Sathiamoorthy and Probert’s effort in overcoming objections to the barrage principally involved adding 80.5MW of power, or 0.87%, for a minimum of £70,117,500 at 1988/1994 prices (table 3). Unsurprisingly, their proposal received little attention.

Table 3 – Total additional price of the 1994 proposal. *1988 prices. **1994 prices. All ratings and prices from Sathiamoorthy and Probert, 1994.

Tidal Electric claim that lagoons solve many of the problems encountered by the barrage;

* Economically, a lagoon would cost approximately £20-25/MWh (2.0-2.5 pence per kWh) compared to £55/MWh (5.5 pence per kWh) for a barrage 19.
* Provide 6-7% of the UK electricity demand, equivalent to 3 or 4 nuclear power stations 19.
* 30% 19 more electricity, based on the largest possible scheme, could be generated at less than half the cost (see above).
* The impounded head would be 40% smaller than a barrage 19.
* No impediment to shipping 18.
* Environmentally important inter-tidal zones are predicted not to be affected as the lagoon would be located 1 mile offshore 19.
* Has crucial backing from some environmental organisations, notably Friends of the Earth 19.

Although the tidal lagoon concept introduces myriad benefits to renewable energy, a major advantage conceded to a complete barrage is tourism. It is possible that relatively small numbers of birdwatchers and water sports enthusiasts will be drawn to a lagoon, if permitted, but attracting industrial visitors would be unlikely.