1 minute ago, studiot said:

I take your word for the 20% - 50 % spare capacity, as i said you are in a position to have better figures than I.

Did you take my point about hot standby requirement? Yes or no.

Just now, sethoflagos said:

This was never in dispute. I presume you read the bit about London being powered from South Wales during the blitz? Necessary at the time no doubt, but it is generally most economic to keep short distances between generation and demand centres.

But there are (were) also arguments for placing the generating capacity near to coalfields, hence the Trent, Soar and Ouse (including Drax).

The Wiki article also implicitly confirms my comment about fragmentation.

And today we see flood warning is certain areas coupled with drought orders in others because the once unified water industry is now in the same boat fragmented and worse because we are without a national water grid.

Edited June 12Jun 12 by studiot
spelling

9 minutes ago, studiot said:

Heathrow excepted ?

Just level it and construct a 15 GW nuclear station on the site. God would smile.

Just now, sethoflagos said:

Did you take my point about hot standby requirement? Yes or no.

I know what hot standby means, AGCR edit (I mean gas fired sorry) stations are the fastest fossil fuel stations for this.

But battery based supply a la Shetland is even faster.

Just now, sethoflagos said:

Just level it and construct a 15 GW nuclear station on the site. God would smile.

The staines gravel is already pretty level.

I do remember a proposal to move London airport to a more suitable site, with a proper transport link, on derelict land.

Heathrow would have then been sold off and the state could have made a massive profit from the real estate value of the site, in the midst of London.

Edited June 12Jun 12 by studiot

2 minutes ago, studiot said:

I know what hot standby means, AGCR stations are the fastest fossil fuel stations for this.

Advanced Gas-Cooled Reactor?! Perhaps you meant CCGT station? I know. Sutton Bridge was one of mine. A little before ENRON hit the headlines for all the wrong reasons.

Just now, sethoflagos said:

Advanced Gas-Cooled Reactor?! Perhaps you meant CCGT station? I know. Sutton Bridge was one of mine. A little before ENRON hit the headlines for all the wrong reasons.

Yes my bad.

I cross posted with my edit when I realised.

On 6/13/2025 at 12:05 AM, studiot said:

But battery based supply a la Shetland is even faster.

Now that the tone of the discussion has calmed a little, I recommend reading this paper: The future of frequency response in Great Britain

It's quite short and not too technical, and deals with the critical consideration of grid stability.

The meat of the analysis is in this paragraph:

3.1. GB grid model

The GB grid model used in this study is based on the swing equation:

df∕dt=f_n2(R+I−kD_nΔf)∕2E_nf.

f_n [Hz] is the nominal frequency of the grid and Δ f=f−f _n. E_n [MW.s] is the total rotational kinetic energy stored in the grid at f_n, which is what we define as inertia in this paper. R [MW] is the FR of the grid, which can be positive or negative. I [MW] is the power imbalance of the grid and is positive when generation is greater than demand and negative when demand is greater than generation. D_n[MW] is the demand of the grid at f_n and k is the demand damping constant, set to 0.02 in this paper.

To be clear, R here represents staged interventions by the grid to maintain frequency within statutary limits in response to imbalances, I, between generation and demand.

In my day, 20% of UK average load was met by three stations (Ferrybridge, Eggborough, and Drax) strung out along just 15 miles of the Aire Valley at the heart of the grid. 14 turboalternators churning out 8 GW This centre was bolstered by a similar capacity generated by a string of somewhat smaller stations (Rugeley, Drakelow, Castle Donington, Ratcliffe-on-Soar, High Marnham, Cottam, and West Burton) on the Trent Valley. Between them, their huge combined angular momentum provided the cental 'flywheel' of the system, to which all more remote generation units were forced (by physics) to follow in both frequency and phase. The resulting high value of E_n resulted in exceptionally low fluctuations of grid frequency, and consequently very rare need for direct intervention by the grid. Hence, the historically excellent stability and reliability of the UK grid.

As the paper referenced suggests, the transfer from coal to renewables will greatly reduce the rotational kinetic energy of grid supply. Essentially, it will become dominated by the considerably smaller nuclear component. And hence, if grid stability is to be maintained, there is going to be a far greater reliance on grid intervention, R. And key stages of this must activate within one second of notice. This is the real challenge to be faced by the transistion to renewables. Everything else is simple in comparison.

Edited June 14Jun 14 by sethoflagos
typo