3 July 2011
As a young graduate engineer in the 1980s I worked on the feasibility studies for the River Mersey Tidal scheme. The River Mersey estuary is ideally situated for the generation of power from tidal flow. The tides on the west coast of England are some of the highest in the world and the shape of the estuary with a narrow neck and a wide body beyond maximises the amount and velocity of the flow. The proposed Mersey Plant could give us 3% of total GB energy in one go. The larger proposed Severn Scheme could have given 8% of total GB energy.
The French are as usual ahead of us and built a massive tidal power station at Rance in Brittany in 1966. This has now been paid for. All they have to do now is open the valves every tidal cycle and let the water into the turbines to give them practically free electricity. The simple nature of the generation means this sort of structure has a design life of 120 years. A typical nuclear plant will only generate for 30 years before being decommissioned. A coal or gas plant will generate for 60 years before it comes to the end of its life. You need to thus build and decommission four nuclear plants or two gas/coal plants to cover one tidal plant.
In the 1980s feasibility study it was concluded that, although the proposal was technically feasible and over the 120 year life won hands down over its rivals financially, it was not financially feasible in the current climate. This was because the assessment was based on only 25 years. No consideration was made of the fact that after 25 years the tidal plant had 95 years of generation ahead of it whilst the equivalent nuclear plant would be knocked down 5 years after it had been paid for.
The reason I am bringing back the memory of my time on the project in the 1980s is that another Mersey Barrage feasibility study has just been completed. This time the project has to consider rising fuel prices, dwindling resources and global warming. What has been the result of this study? The result was the same. The short term view of only considering 25 years and ignoring the rest has again meant that the barrage will not be built. Meanwhile in Northern Brittany the tide turns again, the valves are open and the turbines spin to give free energy.
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