We do not necessarily have to use our tidal basins on 24 hour cycles. Either by leaving the basins empty until needed, or indeed full until needed, they operate as multi – megawatt batteries that can be turned on and off when the grid requires additional power. The timing to match 50 Hz is just that of any other power plant, no special equipment or precautions are required.
And they can be turned on or off at the touch of a button.
The identification of over 40 potential sites for large scale tidal power development means that the available “standby” power levels will be variable because of tidal differences but with some of the larger “open air” water basins the availability of 200 or 300 Megawatts could compensate for a gas station tripping out. Where these are fairly close together (e.g. Bristol / South Wales, Or the Thames / Orwell) then there is potential for a 1 Gigawatt “battery” to be made available should the grid demand it although of course the main site could still just be operated as normal.
There is at least 2 Gigawatts of power storage available.