I AM always a bit puzzled about the claims made for tidal power from the Severn Barrage.

I AM always a bit puzzled about the claims made for tidal power from the Severn Barrage. Supporters of the barrage tell us it will generate six per cent of the nation's power, but they don't tell us when or for how long on each day.

The proposed scheme is unidirectional on the ebb tide and this method will generate power after high tide has dropped a metre or two to give operating head to the turbines until shortly after low tide. According to the Admiralty Tide Tables, power would be generated today (Feb 18) from 2am to 6am and 2pm to 6pm (approximate times).

The 2am to 6am slot is not a lot of use, as we already have excess power at night and the problem is to persuade people to use it. The other slot, 2pm to 6pm, is only four hours, so we still need alternative means of power generation the rest of the time. Tomorrow the tide times will be different, every day they get later by about an hour, so the generating times will differ. When high tide is around 9am/9pm the tides are good and we get more energy. But 3am/3pm tides are lower and produce less energy.

These tidal variations will create major problems for the power companies. It is already difficult for them to cope with fluctuations in demand, they have to crank up expensive short-term generators during times of peak demand. With the Severn Barrage producing fluctuating amounts of power which vary in time and total energy day to day, they will have to have even more short-term stations coming on and off-line, which will increase the cost of production.

Are we to suffer the ills of an ugly barrage and the silting up of Weston Bay only to find that the energy rewards are not there?

MIKE ROGERS

Baker Street

Weston