Roland Perry wrote in message .. .
In article , Terry Harper
writes

Yes, it would be a big gas turbine. Would a few hundred MW be adequate, do
you think?

Dinorwig (Llanberis) was designed as a power station for fast backup.
1,728MW available within 16 seconds, apparently.

Strictly speaking Dinorwig was not designed as a backup generator, nor
is used as one, as it is powered from pumped hydro storage and thus
has a finite time from which it can provide useful energy conversion
before the head of water becomes exhausted.

Its purpose is to provide additional generating capacity during peaks
in demand of the sort created by the nation putting the kettle on
during the middle of soap operas, footie etc. This prevents the system
frequency from sagging to the point of shedding load. On a typical
day, the plant at Dinorwig may only generate electricity for as few as
10 minutes or even less, some of the remainder of the time being used
as a pumping station to restore the reservior's head.

To provide the ability to go on line and generate 1.7GW in 16 seconds
with fossil or nuclear fuelled plant would require an installed
capacity of perhaps 8GW and the associated costs of keeping it in
spinning reserve until called upon.

As Dinorwig and other pumped storage schemes are used to support the
Grid's stability during transient load flows, they are classed as
power compensation plant and as such are operated in England & Wales
by NGT (National Grid Transco), the transmission system operator.

Richard