Football just finished and all the kettles gone on.
That’s a lot of kettles going in, then off, then on, the off, then on (etc.) for a few hours, and all at exactly the same time !
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National Grid warns of possible blackouts
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That’s a lot of kettles going in, then off, then on, the off, then on (etc.) for a few hours, and all at exactly the same time !
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What did you do in the afternoon?
brad465
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Also nationally solar reached a 3GW peak at noon, which isn't a lot in general but sounds quite good this close to shortest day, and double the yearly average of 1.48GW (the average includes all hours of day) in what will probably be a new annual record. In summer the noon peak was around 8-9GW, but I expect that to be exceeded next year if reported high rates of installation continue.
Peak solar output was over 10GW this year.
Gave in and put the central heating on!What did you do in the afternoon?
The last few days have been remarkable for the power network, helped by a windy spell. Yesterday set a new record of 2.75GW as the lowest average amount of electricity generated by Gas power stations for one day since the ‘dash for gas‘ saw lots of new gas power stations built nearly 20 years ago. Right now it’s about half that at at 1.4GW, which I think will be the lowest ever ‘instantaneous’ power by Gas.
This Christmas National Grid have been running with a minimum gas output much lower than recently, and I understand they are well advanced in plans to run a ‘fossil fuel free’ day at some point in the next year or two.
This Christmas National Grid have been running with a minimum gas output much lower than recently, and I understand they are well advanced in plans to run a ‘fossil fuel free’ day at some point in the next year or two.
brad465
Veteran Member
As Clarkson once quipped: "So if you're watching this in Saudi Arabia, PHAHAHA!!!"
(I know they're oil more than gas but overtime the grip of OPEC will weaken)
Dai Corner
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Qatar rather than Saudi Arabia for gas. Eliminating our dependence on countries we'd rather not have to do business with is a good enough reason to support nuclear and renewable generation without even considering climate change.
Norway rather than Qatar for gas, as it happens. Last year around half our gas was from U.K. sources, and almost 40% from Norway. Qatar was about 5%.
Source: https://www.ons.gov.uk/economy/nati...trendsinukimportsandexportsoffuels/2022-06-29
brad465
Veteran Member
What I don't get is how the price per MWh is still often getting to ~£200 during the day; at night it's unsurprisingly going down to £0, even negative, but the aforementioned peak price seems odd when gas power generation is very low and wind is meeting around or greater than half of all demand while generating 15-20GW. The only explanation I can see is the imports and/or Nuclear power must also be very expensive.
Isn't it the case that the "last generator switched on" is what effectively sets the price, so even with the large amounts of renewables load even one gas plant can quickly bring the whole price up?
That said, the pricing generally seems to make no sense at all (on the surface) - for example yesterday between 12:30 and 13:00 the price shot up from £13.65 to £200/MWh, yet there doesn't appear to be any significant changes in generation mix, with imports, coal, hydro, biomass and other, increasing by small amounts whilst everything else decreased. It may well be the case that interconnectors are behind a lot of the price fluctuation, or perhaps just vagueries of the balancing system
That said, the pricing generally seems to make no sense at all (on the surface) - for example yesterday between 12:30 and 13:00 the price shot up from £13.65 to £200/MWh, yet there doesn't appear to be any significant changes in generation mix, with imports, coal, hydro, biomass and other, increasing by small amounts whilst everything else decreased. It may well be the case that interconnectors are behind a lot of the price fluctuation, or perhaps just vagueries of the balancing system
| GW | 12:30 | 13:00 |
| UK Demand | 35.7 | 35.3 |
| Interconnectors | 3.10 | 3.30 |
| Coal | 0.35 | 0.40 |
| Gas | 2.02 | 1.80 |
| Solar | 3.08 | 2.82 |
| Wind | 19.51 | 19.27 |
| Hydro | 0.52 | 0.53 |
| Nuclear | 5.71 | 5.71 |
| Biomass | 1.13 | 1.19 |
| Other | 0.29 | 0.31 |
Nuclear is very cheap at the margins. Imports can vary widely, in line with market prices at origin.
The price is a veritable mix of what the marginal price of generation is, and that includes the price in the European markets we are connected to. There is also a regional effect, in that (put simply) the demand for power is greater the further south you are, but the supply is greater the further north you are. When it’s windy loads of power is produced where we don’t necessarily need it, but not enough where we do, and therefore more expensive forms of generation (such as gas and imports) are used to supply the localised demand.
There‘s a good piece on regional wholesale electricity pricing here:
Locational pricing for Britain’s electricity? | Q3 2022 Quarterly Report | Electric Insights
reports.electricinsights.co.uk
(too long to quote, sorry).
brad465
Veteran Member
Today our imports from France have gone up to 3.5GW for the first time in a while from memory, which suggests they've managed to fix the HVDC Cross-Channel (IFA-1) interconnector to go above 1GW again, given the other 2 cables are 1GW max. A fire at Sellindge in 2021 caused it to be shut down for repairs, but work was only done to get it back to 50% initially.
good spot!
France has got a power surplus at present - it’s not cold there*, it’s windy, and many of their nukes are back on line (with more to come). They are currently exporting 13GW!
*and as it’s not cold, many of their ski resorts are not open for snow sports, which reduces power demand quite a bit compared to what it should be this time of year.
One of the big problems is that, although we have the gridwatch sites giving us estimates of how much electricity is being generated and by what method, we don't have any numbers showing what the inputs are in terms of fossil fuels in order to achieve those results. The 'cost' per unit is dictated by the costs of plant and fuel for each method. For wind and hydro the fuel is free, but the availability isn't reliable. For nuclear the fuel is only around 10-15% of the cost, but for gas the fuel cost is a lot higher, with the plant being relatively cheap.
As I understand it Combined Cycle Gas can react fairly quickly to fluctuating demand, but that comes at a cost in terms of gas consumption. You either have to keep the plant in a hot standby mode (i.e. consuming gas but not generating anything) or shut it down, in which the case a large amount of gas is consumed to restart it. Coal is even worse, which is why the UK appears to be running a small amount of coal generation at a fairly steady rate at the moment.
The best explanation of all this I've found is here, but note this is now a fairly old paper:
HSTEd
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Some studies have suggested that, with respect to power cycling vs continuous output, that the fuel cost of nuclear may be effectively negative.
"Two shifting" nuclear plant and powering it down or reducing output can cause significant thermal and fatigue stresses on the reactor system and the balance of plant. This has implications for maintenance and inspection requirements.
As a result it may be cheaper to just run the reactor flat out regardless, even if the electricity price falls to zero (or even marginally below zero).
This is especially true as a shut down reactor (that does not restart almost immediately) may fall into a 'xenon pit' and not be able to restart for 36 hours or so. That might leave you unable to generate in a forthcoming peak demand period.
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brad465
Veteran Member
Gas and wind seem to correlate strongly between each other in the UK, and for at least a few weeks now gas has rarely got above 10GW, despite the UK's gas power station capacity being 28GW, with wind providing the high teens to 20GW often. The National Grid will be looking at forecasts regularly to predict wind and solar outputs, and base gas demand on that. I'm sure there will be some gas power stations in hot standby mode, but at the moment I can't see how most of them are right now. Of course when gas demand goes up to 20GW+, I would strongly expect all power stations to at least be on standby, with the overwhelming majority running.
A lot depends on the type of reactor: I assume there is a good reason that nuclear powered submarines/ships all seem to use PWRs.
I assumed that is because they're small and compact.
HSTEd
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Extremely compact and comparatively benign reactor chemistry, predominantly.
Whilst nuclear submarines have reactors capable of rapid power cycling they also use fundamentally different technologies to civil PWRs, with metallic fuel and the like to reduce thermal shock problems. And far less sophisticated steam turbine plants (since they care about compactness, not thermal efficiency).
Nicholas Lewis
Established Member
Modern CCGTs can run upto full load in under 30mins so they don't need much notice unlike old coal fired stations which needed 8-12hrs to get them to full load.
The other thing that's been interesting with wind is how even when its contributing a big chunk of generation we are still importing from Europe as there prices seems to drop back far more when renewables have a high contribution than ours do.
brad465
Veteran Member
We have a new wind power record, set earlier this evening at 21.69GW, beating the 20.9GW set in November.
it is a bit odd.
To prove the point we have just broken the instantaneous record for wind generation again - currently 21.7GW*. Gas is under 3GW. And the wholesale price is still over £200/MWh.
*I reckon today will be the most power generated by wind in a day, it will be around 18GW average.
HSTEd
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This problem is inherent to the electricity market system. We just get ever more convoluted "reforms" that aim to conceal this reality.
If we still had a CEGB-type operator using a merit order our electricity prices would be a small fraction of what they are now.
Another privatisation failure.
Nicholas Lewis
Established Member
That figure presumably includes an estimate of embedded wind generation as Elexon data says only just over 17GW at this time but thats NG metered data.
https://bmrs.elexon.co.uk/generation-by-fuel-type
yes this is from Drax’s “insights” - and even that underestimates on occasion.
HSTEd
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National Grid ESO estimated peak embedded wind generation at about 3800MW, although will have to wait a while to see where that peak was. (Full data isn't out yet)
It looks like yesterday (Wednesday) wind averaged over 20GW (20.1GW) for the entire day. This must surely be another new record.
Source: https://grid.iamkate.com/
Source: https://grid.iamkate.com/
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