The UK's National Energy System Operator has issued an unusual market notice requesting additional electricity generation after forecasting a shortfall of almost 1,400 megawatts on Monday morning, amid forecasts of low wind power generation across Europe. The operator said the notice was a routine precaution and that there is no risk to customer electricity supplies.
The notice, issued on Sunday evening, said Neso faced a shortfall of almost 1,400 megawatts in electricity supply margins between 6am and 11am on Monday. It said it would need to find extra generation of about 800 megawatts, the equivalent of a medium-sized gas power plant, within eight hours before a scheduled review at 4am. A second margin notice after that review showed the shortfall had been reduced to 500 megawatts and no further contingency power was required, though Neso said it could still call on plants to generate more than usual between 8am and 11am.
Such notices have historically been used on cold winter evenings when demand peaks. The unusual morning call follows a recent uptick in alerts, including the first margin notices issued during the past summer when heatwaves pushed up demand while curbing generation.
The shortfall may have been prompted by low wind speeds across Europe, which curbed renewable output at the end of last week. On Friday, Neso paid more than ten times the market price of earlier in the week for electricity imported from the continent, a cost ultimately covered through household energy bills. Independent energy consultant Kathryn Porter said these payments included £2,500 per megawatt-hour for power imported via subsea cables and £1,000/MWh to fire up gas plants.
Neso said the notice was a "routine and precautionary measure" to give the market an opportunity to make extra generation available. A spokesperson added: "This is not a warning of power cuts, there is no risk to customer electricity supplies, and customers do not need to take action – Great Britain’s electricity system remains secure."
The operator has faced scrutiny after an independent investigation last month found "cultural issues" in its control room, following whistleblower claims that it was covering up the growing risk of blackouts. The whistleblowers alleged that control room decisions were subject to interference by the company's corporate affairs team.
Neso was previously part of National Grid and came back under government control in 2024.
Analysis
Why This Matters
- The incident highlights the vulnerability of the UK grid to periods of low wind generation, which is becoming a more frequent concern as renewable capacity expands.
- The costs of paying for high-price electricity imports will be passed on to households through higher bills.
- The ongoing scrutiny of Neso's control room culture raises questions about transparency and preparedness for future supply challenges.
Background
The National Energy System Operator (Neso) is the government-owned body responsible for balancing electricity supply and demand on a minute-by-minute basis across Great Britain. It was originally part of the FTSE 100 energy company National Grid and returned to public ownership in 2024.
Margin notices, which request additional generation, have historically been used during cold winter evenings when demand is highest. This summer saw the first such notices issued during a heatwave, and the trend has continued.
An independent investigation last month, prompted by whistleblower allegations, found "cultural issues" within Neso's control room, including claims that corporate affairs staff interfered in operational decisions to protect the operator's reputation.
Key Perspectives
Neso: described the notice as a routine and precautionary measure, stating that there is no risk to customer supplies and that the electricity system remains secure.
Kathryn Porter, independent energy consultant: highlighted the high costs paid to secure imports, with payments of £2,500 per megawatt-hour for power from subsea cables and £1,000/MWh for gas plant generation.
Whistleblowers: have alleged that the grid is becoming increasingly unmanageable and that Neso's corporate affairs team has influenced control room decisions to suppress information about blackout risks.
What to Watch
- Whether the frequency of margin notices rises further as winter approaches and renewable share grows.
- The outcome of the investigation and any reforms to Neso's operational transparency.
- The impact on consumer energy bills as costs for high-price imports are recovered through charges.
Checked
12 claims in this story checked against 1 source: 12 supported.
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- SupportedThe grid operator issued a rare call for electricity as wind output dropped across Europe.UK news | The Guardian: “Rare call for more electricity supplies as wind power drops across Europe.”
- SupportedNeso’s notice cited a shortfall of almost 1,400 MW for Monday morning, amid forecasts of low wind generation across Europe.UK news | The Guardian: “A notice issued by the National Energy System Operator (Neso) on Sunday night said it faced a “shortfall” of almost 1,400 megawatts in its electricity supply margins from 6am until 11am on Monday.”
- SupportedA Neso spokesperson called the notice “a routine and precautionary measure”.UK news | The Guardian: “A spokesperson for Neso, which balances the power system’s supply and demand on a minute-by-minute basis around the clock, said the notice was “a routine and precautionary measure””
- SupportedA Neso spokesperson said there was no risk to customer electricity supplies and customers did not need to act.UK news | The Guardian: ““This is not a warning of power cuts, there is no risk to customer electricity supplies, and customers do not need to take action – Great Britain’s electricity system remains secure,” the spokesperson said.”
- SupportedNeso said it needed about 800 MW of extra generation within eight hours before a review scheduled for 4am.UK news | The Guardian: “The notice said Neso would need to find extra generation of about 800 megawatts, or the equivalent of a medium-sized gas power plant, within eight hours before a review of power supplies scheduled for 4am.”
- SupportedAfter the review, a second notice showed the shortfall had fallen to 500 MW, no further contingency power was required, and Neso could still call on plants to generate more than usual from 8am to 11am.UK news | The Guardian: “A second “electricity margin notice” issued after the pre-dawn review revealed that Neso’s 11th hour margin call helped to shrink its shortfall to 500MW. It said that no further contingency power was required but Neso could still call on power plants to generate more than usual between 8am and 11am.”
- SupportedSuch notices were historically used on cold winter evenings when demand peaked, and the recent alert uptick included the first notices issued during the summer amid heatwaves.UK news | The Guardian: “In the past, these notices would typically have been used during cold, winter evenings, when electricity use is often at its highest for the year”
- SupportedLow wind speeds across Europe may have prompted the shortfall and curbed renewable output at the end of last week.UK news | The Guardian: “This suggests that the shortfall may have been prompted by low wind speeds across Europe, which have curbed the continent’s renewable energy output at the end of last week.”
- SupportedOn Friday, Neso paid more than ten times the market price from earlier in the week for European electricity imports, with the cost ultimately covered through household energy bills.UK news | The Guardian: “On Friday, Neso paid more than ten times the market price of earlier in the week to secure power imports from Europe, which will ultimately be covered through charges on home energy bills.”
- SupportedKathryn Porter said the payments included £2,500 per MWh for power imported via subsea cables and £1,000/MWh to fire up gas plants.UK news | The Guardian: “Kathryn Porter, an independent energy consultant, said these payments included £2,500 per megawatt-hour for power imported via Great Britain’s high voltage subsea cables, and £1,000/MWh to fire up gas plants.”
- SupportedAn independent investigation published last month found cultural issues in Neso’s control room, after whistleblowers accused Neso of covering up the growing risk of blackouts.UK news | The Guardian: “The system operator is under scrutiny after an independent investigation, published last month, found significant and concerning “cultural issues” within the grid operator’s control room. The three-month investigation was undertaken by an external law firm after whistleblowers accused Neso of covering up the growing risk of blackouts faced by the country.”
- SupportedWhistleblowers alleged that control room decisions were subject to interference by the company’s corporate affairs team.UK news | The Guardian: “the whistleblowers claimed the grid was becoming increasingly unmanageable, and that control room decisions were subject to “interference” by the company’s corporate affairs team to protect the reputation of the government-owned operator.”