“Trust me, I’m a doctor” – NESO’s approach to transparency“ by energy analyst Kathryn Porter

In this blog I will carry out further analysis of what happened on 8 January and what NESO has said about it at different times, and highlight the system operator’s disappointing lack of transparency

“Trust me, I’m a doctor” – NESO’s approach to transparency

17 January 2025|Networks|18 Comments

The National Energy System Operator (“NESO”) has been stung by my analysis of the blackouts near miss on 8 January, at one point apparently telling journalists, somewhat pompously that “WE are the National Energy System Operator, and SHE is “just” an independent consultant!” In this blog I will carry out further analysis of what happened on 8 January and what NESO has said about it at different times, and highlight the system operator’s disappointing lack of transparency.

Initial attempts to discredit me did not succeed

In the days following my blog it was picked up by the media and was widely read on X /twitter (430k views)! Here is a selection of the coverage:

• Britons paying ‘£2m an hour’ to keep gas-fired power stations running in freezing temperatures

• Britain ‘came within whisker of blackouts’ after plunge in wind speed

• UK’s blackout near-miss shows risks of Net Zero

• Blackout risk as energy supply warning issued during freezing temperatures as rush to net zero blamed

• UK households face ‘blackouts’ after energy supply warning issued

• Will Britain suffer a power outage? Freezing weather brought UK ‘within a whisker’ of blackout

• How the energy grid came ‘within a whisker’ of blackouts over sub-zero conditions

• The traders making millions by gaming Britain’s power crunch

It was even covered in foreign language press: Wielka Brytania o krok od blackoutu? Poważny incydent pierwszej zimy bez węgla (this Polish headline draws attention to this being the first winter without coal, and yes, I do speak and read Polish!) I was also interviewed on TalkTV and GB News.

I would particularly like to thank Matt Oliver at The Telegraph and David Rose at UnHerdwho both pushed NESO to answer the questions I was posing, sadly without much success, but not for the want of trying!

The first public comment by NESO was:

“NESO operates Great Britain’s electricity network to one of the highest levels of safety and reliability anywhere in the world. Yesterday our control room engineers used our standard operational tools to manage the electricity network and ensure that we maintained enough electricity for our standard operating contingency. At no point were electricity supplies less than anticipated demand and our engineers were able to rebalance the system without the need to consider emergency measures. One of the standard operating reserves held by NESO at all times is for the largest power generator on the system, which last night was 1400 MW, not the 580 MW that has been quoted online,”
– Craig Dyke, Director of System Operations, NESO

Follow-up questions from journalists who had set a deadline of 5pm on Friday 10 January for more substantive information (including a list of the units which were providing the margin and reserve on 8 January) yielded a two-paragraph response to the effect that everything had been fine and we should all just take its word for it. And none of the details that had been requested.

But it did not end there. I continued to be dis-satisfied by the lack of a proper explanation from NESO, and on Monday 13 January published further analysis of NESO’s forecasting errors which contributed to the near miss. Later on Monday, Andrew Bowie, the Shadow Energy Minister said in the House of Commons:

“All our constituents will be aware of the freezing temperatures experienced across the United Kingdom last week, dipping to minus 18° in the north of Scotland. However, many will not be aware of just how close this country came to an energy shortage, blackouts, or demand control—closer than at any point in the past 15 years…

Earlier in the week the National Energy System Operator issued a call for electricity providers to step in to provide extra electricity to meet demand and limit the risk of blackouts, paying 10 times the average daily amount to keep the lights on, all of which will end up on the energy bills of our constituents. With an incredibly tight margin between demand and available power generation, we were once again forced to rely on reliable gas power plants to keep the lights on in this country, showing that gas is and will be a vital component of our energy security for decades to come.”

As those who follow me on X /twitter will know, I have been engaging with the Shadow energy team. Claire Coutino, the Shadow Secretary of State for Energy Security and Net Zero was kind enough to tweet that I should be among a group of market expo

erts advising the Government on energy.

On Tuesday 14 January I recorded a webinar with UnHerd, one of the media outlets that has been working with me to cover this story, with the resulting interview being published to their YouTube channel on the following day.

NESO invents a new concept to mislead the market

Later on Tuesday, NESO published a short 2-pager in which it claimed to have held 3.7 GW of “headroom”.

“Headroom” is defined in the Grid Code as “The Power Available (in MW) less the actual Active Power exported from the Power Park Module (in MW),” where a Power Park Module is an Offshore Power Park Module or an Onshore Power Park Module which are themselves defined as non-synchronous generating units powered by an “intermittent power source”. In other words, NESO is playing with words. We are concerned with Margin and Reserve. Headroom, as defined in the Grid Code, has nothing to do with it, or if it does, NESO is claiming, incorrectly there was 3.7 GW of intermittent generation spare at the peak on 8 January!

It’s also curious that in the Electricity Margin Notice, NESO said there was a 1,700 MW shortfall versus required contingency of 900 MW (later adjusted to 1,120 MW shortfall vs 448 MW contingency). If there was always this mysterious “headroom” of 3,700 MW, why did we need the Electricity Margin and Capacity Market Notices? Surely there was plenty of spare generation around?!

Elsewhere in the paper, NESO says that the market tightness was exacerbated by there being roughly 3 GW of interconnection to Europe that was unavailable. It said this is “not unusual at this time of year, as maintenance is carried out over the Christmas period and returns typically through January”. It also pointed out that the Winter Outlook published in early October highlighted this period as one in which margins are generally expected to be the most tight.

So it is a little surprising that in the Winter Outlook, NESO said it assumed that 6.6 GW (de-rated) net imports would be available via interconnectors at times of tighter margin. On 8 January, only 6.28 GW was actually secured at the peak. If there is an expectation of maintenance at this time of year, perhaps more conservative assumptions should have been made.

According to this paper, peak demand was 45.841 GW at 7:30pm. This corresponds to the Initial Demand Outturn, whereas the Initial Transmission System Demand Outturn data from BMRS was 46.825 GW (at 17:30). The Initial Demand Outturn takes into account transmission losses but does not include station transformer load, pumped storage demand or interconnector demand, whereas the Initial Transmission System Demand Outturn takes into account transmission losses, station transformer load, pumped storage demand and interconnector demand. This is the higher number, and represents the number that has to be met by generation, so there is a question as to why NESO mentioned the lower number.

Operational Transparency Forum is told another story

On Wednesday 15 January, a week after the event, a member of the control room team walked though what NESO did leading up to the peak on 8 January during the Operational Transparency Forum (“OTF”) call. Interestingly he did not say what happened at the peak, or what they learned afterwards, it was a purely forward-looking view. He described how in the morning of 8 January, a planned network outage was cancelled, an ongoing network outage was ended, planned commissioning work was deferred to reduce risks on the grid, and models were adjusted to take a more conservative view of the availability of units returning from outages.

In addition, Medway CCGT was asked to return to service and Sutton Bridge was asked to run when it had planned not to for reasons that are not public (there was no notice of maintenance or similar on REMIT, they just had a notice to deviate from zero of 360 minutes which is too long for normal BM participation – questions were asked about this during the call, but NESO batted them away saying they won’t comment on individual units).

I can’t quite figure out what was going on with Medway from its REMIT notices but I assume that Amira, whose availability data I used in my previous analysis included zero output from it since it was on an outage, and that on the day, it was able to generate 340 MW during the evening peak, increasing the margin by this amount.

NESO also apparently gained 150 MW from EWIC and Moyle interconnectors with Ireland, but I don’t understand this claim since BMRS indicates no positive flows on these interconnectors (exports are not shown) during 8 January. Amira shows exports that day for Moyle of 150 MW and that this was in line with the operational schedule. It’s possible this schedule was changed early enough to not appear on the chart. It was a similar story on the East-West interconnector (exporting 100 MW). Both exported larger amounts before and after the peak. However, when I ran my numbers I took this into account, so my analysis was after this addition, if there was an addition.

It’s worth noting that we almost always export to Ireland. So much so, that I didn’t even look at the Irish interconnectors when I made my initial analysis since I think of Ireland as demand on the GB grid. The additional capacity NESO says it secured on the Irish interconnectors was a reduction in exports, not an increase in imports, ie it effectively reduced GB by demand a small amount. Ireland was also experiencing similar weather conditions to us and a tight grid (there is a single unified power grid for the whole of island of Ireland, both Northern Ireland and the Republic of Ireland).

There was also 180 MW of Demand Flexibility Service which I overlooked in my previous analysis (pity it wasn’t the 2 GW demand-response that used to be available under Triad avoidance!)

Interestingly, one participant on the call challenged NESO about the availability of Short Term Operating Reserve (“STOR”) and Positive Balancing Reserve (“PBR”). He said that batteries and peaking plant often run in the wholesale market, despite having a STOR or PBR contract, even though this is explicitly against the rules, because plants that are running cannot provide reserve.

The questioner said this was a particular problem on 8 January – which makes sense because the amount of money that could be made in the wholesale market was significant – cashout prices went as high as £2,900 /MWh. The answer was that if units do this they do not receive availability payments and on top of that a penalty regime was recently imposed (the latest STOR terms and conditions are here). There was a further question about publication of the penalties and NESO said it may consider publishing aggregate penalties as it does not publish performance data on balancing services at the unit level.

NESO was asked if any non-BMUs were included in the margin. The answer was that most comes from BMUs but there is some from STOR and Fast Reserve. (A BMU is a Balancing Mechanism Unit).

What have I been able to find out for myself: my original calculation was sound!

With NESO continuing to refuse to explain which units were providing the spare margin and reserve on 8 January, I have looked (with the much appreciated help of one of my readers who posts as “It doesn’t add up…”) at the Maximum Export Limit of all BMUs connected to the transmission system on 8 January, excluding wind and interconnectors which I looked at separately, to see what generation would have been available to run if needed.

Peak demand was at 5:30pm ie at the end of Settlement Period (“SP”) 35 and the start of SP 36. SP35 generation was slightly higher than SP36 so I used that for my analysis. The API returns MEL for the following classes of assets: 2 = aggregated, C = consumption, E = embedded, M = non-pumped hydro, T = transmission-connected and V = virtual power plant.

I added up the MELs for each of these categories. Then I excluded wind and solar because their MELs indicate what they could generate on a windy/sunny day, and double-counting (within the settlement period some assets had reported MEL multiple times, but obviously could only run once, so I kept the entries closest to 5:30pm which is when I believe the peak was, rather than 5:00pm). I also excluded the MEL of units that had STOR contracts but did not run in the wholesale market since they should be providing reserve instead of margin. I then added back the wind which actually did run, and actual net interconnector imports.

This gave me total availability of dispatchable generation plus actual wind output and actual net interconnector imports of 47.290 GW ie 465 MW higher than peak demand, which is not far away from the 580 MW of my original analysis.

There was some easily identifiable headroom. As mentioned in the OFT call, Sutton Bridge had not planned to run on 8 January and was asked to make itself available in the Balancing Mechanism (“BM”). It was accepted at its Stable Export Limit (“SEL”), so there was about 400 MW headroom to the MEL. Connah’s Quay offered itself at £2,900 /MWh in the BM and was accepted at SEL for three units and MEL for the other, giving another c300 MW total. Similarly, Rye House, which was offering itself at £5,500 /MWh in the BM was also accepted at SEL giving another 300 MW spare, except that NESO stopped extending it at from 4:30pm and by 5:30pm it was fully offline. It actually reached zero at 5:15pm, and with a ramp time of about 25 minutes to MEL, it would not have been able to reach full load by the peak.

While these assets could be called on to meet regular demand, they should not be treated as reserve. It takes around 25 minutes for a CCGT to start from zero to MEL, and 15 minutes to increase from SEL to MEL. This is too slow to be part of the initial response to the loss of generation covered by reserve. Normally batteries respond immediately until Dinorwig, the largest pumped hydro plant in Europe at 1,800 MW starts up taking 16 seconds to reach full load (water drops through its six vertical turbines in a way which is incredibly cool!), and this can run for 5 hours at full load, giving time for gas power stations to ramp up, even from a cold start which would take over an hour.

Looking at what Dinorwig did on 8 January:

• Unit 1 was at MEL (300 MW) during the peak

• Unit 2 was unavailable all day

• Unit 3 was at MEL (300 MW) during the peak

• Unit 4 was at MEL (300 MW) during the peak

• Unit 5 was unavailable all day

• Unit 6 was unavailable all day

This means Dinorwig would not have been able to respond to generation loss since the available units were already running!

There was 848 MW of contracted STOR, but, noting the above comments, I checked the PNs ie actual running profile of the assets and found they generated 599 MW in SP35. A couple of the units generated a lot. Stripping out the units that ran, those that didn’t could have provided 532 MW of reserve and not the 848 MW contracted. Fast Reserve data for 8 January are not yet available on the NESO portal. Data available for 1 January suggest there might have been 50-150 MW of Fast Reserve at the peak. So total procured reserve was maybe 700 MW.

Both my bottom up and top down analyses have yielded essentially the same result – about 500 MW of margin at the peak on 8 January. On top of this there was about 700 MW of reserve. This means that the single largest infeed loss of 1,400 MW could not have been covered. The 3.7 GW “headroom” appears to be a complete fiction, which could only be met by units that are not BMUs as these are the ones I considered (other than some STOR units). However, NESO could clear this up very easily by simply publishing the list of units providing margin and reserve at the 8 January peak, including volumes.

Someone at NESO told me they always cover the Security and Quality of Supply Standard (“SQSS”) because they have to – well everyone that drives a car “has” to have car insurance, but many people don’t and that is generally only discovered either when a third party tries to claim on the non-existent insurance or the police check for some reason such as the driver committing a motoring offence or other crime. This seems analogous – NESO “has” to secure the SQSS, but is anyone actually checking? Or are Ofgem and DESNZ assuming it’s fine and will only check after demand control or a blackout take place?

The questions that remain

Unfortunately we still do not know:

• The actual difference between available supply and demand at the peak on 8 January

• What the actual 1-minute peak demand was (rather than the half-hourly peak) – ie the highest instantaneous demand that had to be met

• The corresponding actual available supply from generators, batteries, interconnectors and demand side response

• Which units exactly provided the margin by which available supply at the peak exceeded demand at the peak and which units provided reserve
  

• What the difference was between what actually happened at the peak and what NESO thought was going to happen when the EMN was cancelled

On this last point, NESO was conspicuously silent in the OTF call (which I was unable to join live otherwise I would have asked myself). Much has been made of the cancellation of the notices, but these appear to have been based on inaccurate demand forecasts, so their cancellation is not comforting!

My analysis suggests NESO was unable to meet the single largest infeed loss and was therefore in breach of the SQSS. I invite it to DEMONSTRATE ie not simply assert, how it did comply with the Standard.

On its website, NESO says “We actively embrace the need to share our data with our customers and the industry, fostering transparency, innovation, and collaboration.” Sadly, it is not putting this claim into practice!