On 10/12/2012 17:30, Corporal Jones wrote:
CCGT (I presume this is gas)

Yes. And as no-one has seen to enlighten you:

Combined Cycle Gas Turbine is basically a jet aircraft engine connected
to a generator. Then because the exhaust is hot you can run a steam
engine off it.

Open Cycle Gas Turbine doesn't have the steam engine, so it's less
efficient.

You can run a CCGT in open mode, and that part of it will fire up in
minutes. The steam part takes ages, which means it doesn't respond well
to a sudden increase in requirements when the wind drops.

Andy