1994 proposal

Sathiamoorthy and Probert 16 called for a further review on the prospective development of a Severn barrage, only 5 years after the previous one was rejected, by suggesting an integrated technology approach. Their proposal was closely related to the 1989 study but with a number of minor adjustments, including a slight deviation in the barrages’ position. No attempt was made to address previous concerns of insurmountable costs, financial or environmental.

Crucial to the 1994 plan was the addition of turbines driven by wind and wave power. Sathiamoorthy and Probert argued that this diversification would ensure a smoother power delivery to the national grid. As the energy generated from tidal regimes could only be produced on the ebb tide, there were 2 periods of 6 hours every day where no output could be provided. A more consistent energy supply, they insisted, would better serve grid power requirements and reduce the necessity of energy production from other sources during flood tides.

A total of 150 wind turbines were proposed to be placed along 15km of the barrage, each rated at 450kW that would be capable of producing approximately 177,438MWh (0.177TWh) annually 16, at the expected average wind speed of 8.97m/s.

The 1994 proposal envisaged sourcing additional power from the ‘sea clam’ design. With a diameter exceeding 60 metres and weighing circa 1,000 tonnes, the clams harness wave power by forcing compressed air through turbines via flexible air bags; permitting use irrespective of wave direction. However, the installed capacity would have provided only 13MW with 11,195 – 34,164MWh annually at a cost of £11-13.2 million 16.