The UK's National Energy System Operator (Neso) is facing intense scrutiny over allegations it covered up its own vulnerabilities during a heatwave in late June. The claims, which have been debated in Parliament, centre around senior managers allegedly prioritising Neso's reputation over the stability of the power system. Whistleblowers within the organisation reportedly told MPs that control room staff were instructed to abandon standard procedures for logging their efforts to stabilise the grid, potentially leaving a trail of inconsistencies in the audit trail.
Shadow Energy Secretary Claire Coutinho alleged in Parliament that Neso's corporate affairs team attempted to sway operational decisions to protect the organisation's image. She stated that employees spoke out because they were deeply concerned about the strain on the grid and claimed senior bosses 'were risking blackouts to protect Neso’s reputation'. The allegations have sparked a formal investigation, with independent investigators from Eversheds Sutherland commissioned by Neso to examine the events of the last week in June.
The heatwave that gripped Great Britain in late June was marked by unusually high temperatures and reduced output from wind turbines and nuclear plants across Europe. This led to an immense pressure on the electricity network, prompting Neso to implement emergency measures usually reserved for peak winter demand – a first in summer. To mitigate the strain, Neso spent nearly £800,000 between mid-April and mid-July incentivising consumers to reduce their electricity consumption.
The grid's frequency, which Neso strives to maintain at approximately 50Hz, dipped close to its operational limits of 49.8Hz and 50.2Hz during this period. On 23 June, the frequency remained under pressure for nearly an hour, reaching a low of 49.66Hz – still above the statutory lower limit but indicating significant stress on the system.
A former Neso employee suggested that the prolonged period of lower-than-usual frequency may indicate the organisation was running out of less drastic options before potentially needing to disconnect industrial users. They highlighted that while a 0.2Hz change might seem minor, it signifies a much greater vulnerability and increases the risk of unforeseen events that the strained system may not be able to absorb. Neso has acknowledged 'sustained pressure on power networks' but has downplayed these concerns.