On 11/12/12 21:40, Andy Champ wrote:
On 11/12/2012 02:34, The Natural Philosopher wrote:

no. It means it doesnt repsond well to cold starts. Its actually a fully
dispatchable power plant and whilst wear at say half power is obviously
not much less than full power, gas consumption tracks very well with
output.

So there is a tendency to use rather more than you need running below
full chat.

Giving you emergency headroom. And at the moment we have 2GW or so
pumped storage to take care of short term peak requirements.


How the heck do they get the steam side of it up and running in 20
minutes? I'd assumed it really was a shaft turbine (and you can fire
them up full power from cold, although it's cruel) feeding some kind of
boiler with the exhaust.


I think they have very small flash steam type boilers.

So - 20 minutes to get the oil warmed up, let the blades heat evenly,
and the GT part is running. I can easily believe that.

Better than that. I think the gas turbine is pretty much full output in
10-12 mins on the latest ones. From a cold start.

But surely the steam must take longer? And surely until the steam is up
to heat you're using just as much gas for the turbine side as you would
after the steam is running?


Yes, the steam does take longer.. thats 40 mins or so. But yes, they are
running at that point at OCGT efficiency - 37% or so. As opposed to 60%
plus with the steam section up. I had some time/output curves somewhere.


I'm obviously missing something. Comes of having fans an inch across in
my kit...

Though short term (~= ad. breaks) isn't what bothers me. It's the 3
days flat calm nationwide we get occasionally.


Like today.

I ****ed myself larfing when some mad ozzie bitch who runs the green
party was on 'Jeff Randall' who said that the way to solve the energy
crisis wasn't to use gas at all, especially not fracked, offshore wind
farms solar panels and economising would be all we needed to do.

It was by then dark, freezing cold, and the total wind output across the
UK from over 6GW of installed kit was less than 1% of the national
demand. Which peaked at 56.7 GW.

I was wondering whether to write to her and ask her to send me some of
what she had been smoking, but then I realised it had patently caused
terminal brain damage.



Andy


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