Neso faces whistleblower probe over UK grid heatwave strain
Britain's state-owned grid operator has hired external lawyers to investigate whistleblower claims that managers suppressed records of severe system strain during a summer heatwave, exposing the operational fragility of the UK's energy transition.
The National Energy System Operator (Neso) has brought in investigators from Eversheds Sutherland to examine allegations that senior staff ordered control room workers to skip standard note-keeping during late June's record temperatures. Shadow energy secretary Claire Coutinho told parliament the whistleblowers alleged managers were "risking blackouts to protect Neso’s reputation".
The late June heatwave created a perfect storm for grid balancing. High pressure stalled wind turbines, heat affected gas plants, and French nuclear exports dropped just as British demand for cooling surged. Neso was forced to deploy emergency measures typically reserved for winter scarcity for the first time in summer, resulting in millions of pounds in payments to gas power plants for short-term generation.
Data highlights the physical strain on the system. Grid frequency, a critical metric for preventing blackouts that Neso targets at 50Hz, dropped to 49.66Hz on 23 June. While above the statutory 49.5Hz cutoff, it sat at the edge of Neso's 49.8Hz to 50.2Hz operational limits for nearly an hour. Neso also breached standard trading limits on subsea interconnectors multiple times, including an emergency call for 500MW from the Netherlands on 24 June.
Balancing these tight margins came at a direct cost to the system. Figures show Neso spent almost £800,000 between mid-April and mid-July paying consumers to reduce their electricity usage. These demand-side schemes are designed to prevent far more expensive emergency actions, such as disconnecting industrial users.
The governance allegations carry significant weight because Neso only recently became a state-controlled entity. The government bought the operator from FTSE 100 company National Grid for £630m in late 2024. A former employee noted the shift in pressure: "Whether there were direct orders to cover up a scandal or not, individuals are potentially being put in an invidious position that might inhibit them from taking the correct action."
Neso director Craig Dyke defended the system's performance, noting that "no customer demand was disconnected, frequency remained within statutory limits, the voltage stayed within limits and no lines or cables were overloaded". Chief executive Fintan Slye wrote to regulator Ofgem asserting that policies exist to prevent corporate interference, but the ongoing investigation will test whether political pressure is compromising grid security.
