Britain power exports curbed as grid pressure rises during heatwaves

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Britain curbs power exports

Highlights

National Energy System Operator restricted wholesale power exports via four interconnectors to zero capacity during margin extremes on July 24, 29, 30, and 31.
Britain’s export limits aimed to preserve domestic electricity supplies amid high heat-driven demand, straining cross-border trading with Belgium, Denmark, Norway, and France.
On June 23, Neso also abruptly cut exports to the Netherlands during low wind output, now investigated by the regulator after whistleblower allegations of security concerns.

July export limits on interconnector cables

As reported by the Financial Times, the state-owned National Energy System Operator restricted wholesale market exports through four of Britain’s 10 interconnector cables during several hours in July to preserve domestic electricity supplies.

Neso told traders not to export power on some periods via the Nemo, Viking, North Sea Link and Eleclink cables, which connect Britain with Belgium, Denmark, Norway and France. Financial Times analysis of Neso data shows maximum day-ahead export capacity on one or more of those links was cut to zero because of “margin extremes” on the morning and evening of July 24, and on the evenings of July 29, 30 and 31, when Britain and Europe were experiencing high temperatures.

Neso says the limits provide an added layer of security and were agreed and used by system operators where needed. It adds that the interconnectors still play an important role in secure and efficient cross-border electricity trading.

The operator says the export restrictions are part of its established approach to managing an increasingly dynamic electricity system and maintaining security for consumers. During an industry forum on Wednesday, Neso also says that even if gas-fired plants appear available when margin-extreme restrictions are used, network cable constraints can prevent that power from being moved to the locations where it is needed.

Summer demand pressures and market implications

Summer is becoming more difficult for power systems as hotter weather raises demand for air conditioning and reduces the efficiency of power plants. Drought conditions in Europe are also contributing to nuclear plant shutdowns where river water for cooling is insufficient.

Britain and continental European countries rely heavily on cross-border electricity trading to balance supply and demand, but those flows can reverse quickly as market conditions change. Phil Hewitt, director at energy market specialist Montel, says political shifts toward more populist positions could create risks for the system.

The July restrictions follow a separate incident on June 23, when Neso abruptly cut exports to the Netherlands during an evening period of low wind generation and heat-driven demand. That episode is now under investigation by the energy regulator and lawyers appointed by Neso, while whistleblowers in its control room have alleged the system was not being run securely, claims later raised in parliament by shadow energy security minister Claire Coutinho.

We previously reported on Neso’s July export limits on several UK interconnector cables, when day-ahead export capacity on key links was temporarily cut to zero during periods it classified as “margin extremes” amid heatwave conditions. That coverage also noted how rising summer demand and operational constraints are increasing pressure on grid security and cross-border power flows, with the system facing added scrutiny after earlier incidents and whistleblower allegations.

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