Talk:National Grid (UK)
From Wikipedia, the free encyclopedia
 |
This article is part of WikiProject Engineering, an attempt to build a comprehensive and detailed guide to engineering on Wikipedia. If you would like to participate, you can edit this article, join the project, visit the project portal, and contribute to the project discussion. |
| ??? | This article has not yet received a rating on the quality scale. |
| ??? | This article has not yet received an importance rating. |
Contents |
[edit] Cost per kWh of Transmission
User:Engineman - Can't you find some published material on the transmission costs for wind power? I appreciate this is an important subject, but the current claim seems to be based only on your own research. The policy against original research does not only apply to factual information, but also to "arguments, ideas, data, or theories." Thanks, Crosbiesmith 20:12, 15 November 2006 (UTC)
Crosbiesmith - Sorry I do not understand your point above - I have referenced in the article the published rates for the cost of the transmission network from the National Grid themselves, so that is surely a solid reference and not research.
http://www.nationalgrid.com/uk/Electricity/Charges/usefulinfo/
I have then performed an obvious calculation and divided the total receipts based on that charging rate and divided it by the published total of kW hours sold, to give the average unit rate of the cost of the transmission network.
So I have taken published reference source material and shown that at the present, the entire cost of the UK national Grid transmission network is the surprisinly low cost of 0.2 p/kWh.
I do not see how that is original research, or how it needs any further reference, but correct me if I am wrong.
I have then, purely by way of example, said, that by inference, if the size of the transmission doubled,trebled or quadrupled (none of which I am saying will happen) then this would presumably , double, treble or quadruple the cost of transmission.
The original calculation was in a paper read at a conference at the Open University so surely that counts as a reference in its own right.Engineman 14:37, 16 November 2006 (UTC)
http://www.ukerc.ac.uk/content/view/258/852
- It was only the last paragraph, the example concerning wind power, that I was questioning. I didn't check the first part. Was the paper read the 'UKERC Intermittency Report'? Or was it some other paper? - Crosbiesmith 19:47, 16 November 2006 (UTC)
Apologies Crosbiesmith - I gave wrong reference - should have been this:
http://eeru.open.ac.uk/conferences.htm#jan06
crosbie smith - ok I see your point now....and have reworded .....hope that suffices.... engineman...
OK, just done a massive rewite of this section. Hopefully the explanation is somewhat clearer. RDevz 18:41, 26 March 2007 (UTC)
[edit] Losses
In the losses section:
Fixed losses: 266 MW (consists of corona and iron losses; can be 100 MW higher in adverse weather)
Is iron a typo? The wikilink to iron doesn't make it any clearer. JimChampion 86.144.73.92 20:10, 5 December 2006 (UTC)
[edit] Transmission costs
Ive put back the estimation of transmission costs as being 0.2 p/kWh since it was removed without any explanation, discussion or counter argument.Engineman 21:58, 3 April 2007 (UTC)
The reasons for my removal of it were twofold: Firstly, the section simply didn't flow properly. Secondly, you don't appear to have understood the underlying charging methodology. I'll refer you to the Statement of the Use of System Charging Methodology (found on http://www.nationalgrid.com/uk/Electricity/Charges/chargingstatementsapproval/ ), which explains how the charges are calculated. It simply isn't a case of Triad demands - they're only used in determining how HH metered sites are billed for TNUoS. NHH sites are billed based on their total consumption between 1600 and 1900 local time over the course of an entire year, and generators are billed based on the amount of TEC they have.
If you want to work out the cost of transmission, a much better way is to divide the total allowed revenue (see: Transmission Price Control section of Ofgem's website (www.ofgem.gov.uk)) of £653m in FY 2006/07 by the total demand of the GB transmission system, of around 360 TWh. This gives you an answer of 0.18p/MWh. Yes, this is similar to what you have already, but it's a sounder basis, as opposed to blindly asserting it. RDevz 23:37, 7 April 2007 (UTC)
RDevz - thanks for the correction - can't accept it was blind assertion I spelt out exactly my assumptions which were near enough. Could you, since you obviously know a lot more about it than me, correct the article on transmission costs then? I assume you mean 0.18p/kWh not 0.18 £/MWh. The point is the costs are very low compared to the energy and other costs - presently around 8 p/kWh by the time it gets to my house any way. Engineman 20:32, 24 April 2007 (UTC)
Um, yeah. £0.18/MWh is obscenely low. I think I meant £1.80/MWh. In my defence, it was late at night. I'll make the necessary adjustments when I'm more awake. RDevz 02:28, 25 April 2007 (UTC)
Update from an expert, Bernard Quigg, CEng. etc writes"
Dave, Yes and no. So long as you don't actually use the transmission system to move power any distance it is cheap. Otherwise it is not. Thus we pay triad charges of 2200 pence per annum for a kW of capacity and the system load factor is about 0.6. Triad charges alone are circa 2200/8760 with the answer divided by 0.6. Thus for us, triad charges are 0.42p/kWH. If we add the exit charges hidden in distribution charges and charges for the generators to put power into the network then we will not be far off the 1p/kWH for say about 200kM of transmission. Do the transmission losses appear in the allowed revenue? If they are put into the trading mechanism they may be hidden as they are not then in the allowed revenue. Rgds Bernard Quigg"
I would only add that the charges Bernard is talking about are for the extreme South West where they are bound to be more expensive...but I suppose that is fair..Engineman 17:52, 25 April 2007 (UTC)
[edit] Further comments on Bernard Quigg's points
“How much does it cost to shift electricity within the UK at semi market related prices?”
Bernard,
I am sure your facts are correct, but I don’t think your answer to my question is right.
Any generator will have to pay the access charges be they a new nuke or a wind farm and they will appear in the respective business case so don’t count.
All electricity that comes from a GSP no matter what its origin or distance has to pay the exit charges so don’t count either.
So the cost of getting it say 200 km (surely 400 km) from a point in the HV near the large coal stations to the Wessex Area GSPs will be only the Triad charges, and as you say these are about 0.42 p/kWh,.
My error had been in averaging the Triad charges for the whole country who pay much less because they are nearer to the coal field power stations than Wessex which is why I got 0.2p
So it seems to me that the answer to the question “ how much does it cost to shift electricity within the UK at semi market related prices over about 200 km (surely 400 km) is about 0.42 p/kWh.
Any advances anyone?
Engineman 20:10, 25 April 2007 (UTC)
[edit] Comments from GB
There is another factor to consider here. The total transmission cost is apportioned between generation and demand users on a 25/75 split (at least it used to be this). The total costs are based on the transmission system usage at the three peak periods (i.e. triads). Therefore if you are going to use triad payments as an approximate method to estimate the cost of transmission then you have to increase this by about 1.33 to account for the 25% contribution from generation that is hidden from your triad charges.
Just for reference, a new-build 275kV double circuit line will give a "firm" capacity of about 800MVA and a recent cost estimate is in the region of £1.2M/km installed. This equates to a capital cost of £1.5/kVA/km or £300/kVA for the 200km reference. This asset probably has a 40 year useful lifetime and so apply a reasonable discount rate to calculate the replacement cost of transmission. This will give an upper end cost estimate.
Regards,
G Engineman 17:35, 26 April 2007 (UTC)
[edit] Comments from a leading UK consultancy
Maurice
Firstly, Triad is locational and so you cannot extrapolate a southern triad into a national revenue.
Secondly, Triad is a return on the fixed costs of providing the wires and not a cross-subsidy.
Thirdly, BSUoS is a mix of mainly bought in transmission services (reserve, frequency response, reactive power etc). The exception is constraint costs, which may be considered a potential cross-subsidy for wires not-provided, except that wires not-provided, do not go into the asset base and earn a return anyway.
Finally, both BSUoS and Triad now cover for GB wires and services and not just NGET’s transmission system.
The final transmission price control Ofgem proposals for the 5-years starting in April 2007 give:
Total allowed revenue for TNUoS (NGET, SPT, SHETL): £1299m. This is 73% on supply and 27% on generation. This gives an average triad on peak day throughput of 60 GW (that was the peak for 2005/6) of £15.59/kW for demand. Generation TNUoS is based on TEC rather than peak day throughput but I am not sure they are interested in that. So approximating as £2.75/MWh
BSUoS incentive for 2007/8 is proposed at £440m (of which about £80m would be allowed for constraint costs). On a throughput of 344.8 TWh (2006/7 but I haven’t checked on allocation of losses in the BMRS figures for initial demand outturn on which I based this figure) then BSUoS is about £0.64/MWh on generation and on demand.
This gives £3.40/MWh on demand plus whatever comes through distribution on the T/D connection charge
I am also intrigued by their use of figures on diesel reliability. Outside demand control it is 85% but in demand control (presumably offered into standing reserve?) it is 50% due to load management in storms.
By the way, what is the concern about NGET revenues given that we have Ofgem attempting to keep them under control they will not be significantly different from what competition could deliver – i.e. that is what it costs to run the system and only limited fat can be carved out.
Rob
Engineman 17:38, 26 April 2007 (UTC)
[edit] Major incidents
I've added a bit on the 28 May 2008 DCI but I'm know little about the technicalities and details appear to be scarce because they "want to maintain confidence in the network" as someone said on Radio 4 !? I presume that a DCI is a sensible criteria for inclusion although the last one occurred 4 years ago which seem rather too frequent ? The big one would presumably be the 1987 storm damage. Is it correct that too low a voltage is as damaging as too high a voltage ? What are the agreed bands ? They talk about frequency but do they mean voltage ? It would be nice to have a section on the emergency procedure, here's the link [1]. Thanks -- John (Daytona2 · Talk · Contribs) 13:10, 31 May 2008 (UTC)
