nuclear-news

Nuclear sector says more reactors needed after Neso requested increased electricity grid capacity

10 Nov, 2026 By Tom Pashby, https://www.newcivilengineer.com/latest/nuclear-sector-says-more-reactors-needed-after-neso-requested-increased-electricity-grid-capacity-10-11-2026/111

The energy operator informed the electricity market on Monday that the grid needed more generation, leading the nuclear sector to demand more reactors be built.

National Energy System Operator (Neso) issued an electricity margin notice (EMN) on Sunday 8 November at 7:17pm, covering 6am to 11am, saying: “There is a reduced system margin.

“System margin shortfall 1388 MW. The current contingency requirement is 808 MW. [Zero] MW of generation is excluded from the available system margin due to system constraints.”

System constraints can include obstacles such as transmission lines not being able to carry any more electricity from offshore Scottish wind farms to high-demand areas in the Southeast of England, which could result in wind farms being paid to stop generating electricity.

Also in the EMN, owners of electricity generators were asked to inform Neso of any additional capacity they could bring to the grid.

It is understood that low wind, forecast at less than 1GW, was contributing to the tighter margin during the morning period.

The fundamental reason for issuing an EMN is to protect the operating margin – the buffer between supply and demand – rather than due to there being a forecast risk of blackouts.

In a statement, a Neso spokesperson said: “We have issued an electricity margin notice for tomorrow morning, as a routine and precautionary measure, giving market participants the opportunity to make additional generation capacity available.

“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.”

At 09:11 on Monday 9 November, Neso cancelled the EMN.

A Neso spokesperson said: “We have now cancelled the electricity margin notice covering the period of Monday morning.

“Electricity margin notices are routine and precautionary measures, giving market participants the opportunity to make additional generation capacity available, which they have now delivered.

“This was not a warning of power cuts and there was no risk to customer electricity supplies.”

An Ofgem spokesperson said: “Neso issued an Electricity Margin Notice this morning, which was subsequently cancelled once sufficient capacity became available.

“These notices are a normal and precautionary part of operating the electricity system and managing supply and demand.

“There was no risk to customer electricity supplies and consumers did not need to take any action. We remain in close contact with Neso and government and continue to monitor the operation of the system.”

Regen is a company providing expertise on how to transition the energy system to net zero.

Explaining the context of the notice, Regen clean power & markets policy lead Georgina Morris-Rowbottom told NCE: “An electricity margin notice is a tool Neso uses to tell the market it needs more spare capacity.

“An export agreed yesterday may have made sense at the time, but if the wind drops or a power station goes offline, Britain may need more power at home.”

Morris-Rowbottom continued: “Consumers are right to ask why they should pay to fire up more gas generation while we’re exporting, but those same cables can bring in cheaper power at other times and save us from having to turn up gas plants here.

“To support energy security and consumer value, the priority must be giving the market clear signals, early enough to act, when Britain needs more power.”

Reacting to the EMN, Nuclear Industry Association chief executive Tom Greatrex said: “Britain cannot afford to lose its nuclear capacity.

“As existing nuclear power stations close without replacement, we risk greater exposure to volatile gas prices, soaring balancing costs and increasingly insecure electricity supplies.

“We must act now to rebuild our nuclear capacity and secure the reliable, homegrown, 24/7 power that households and businesses need.”

Neso previously issued an EMN for 28 September, after it has identified a system margin shortfall of 1,400MW for the period from 4pm to 7pm. This was later reduced to a projected shortfall of 104MW. Neso later cancelled the EMN.

Later, on 12 October, Neso used a different tool called an ‘emergency assistance’ because it had to buy 1.2GW of electricity from a French interconnector cable after a National Grid Electricity Transmission (NGET) asset took longer than expected to return to service.

November 15, 2026 - Posted by Christina Macpherson | ENERGY, UK