The government’s energy emergency committee will give a verdict on National Grid’s handling of last Friday’s nationwide blackout within weeks.
The business secretary, Andrea Leadsom, has tasked the government’s Energy Emergencies Executives Committee with completing a review of the system operator’s role in Britain’s first major blackout in a decade within 12 weeks.
It will also consider whether future power cuts could be prevented and how to minimise the impact of a blackout on people and essential services when they do occur.
“National Grid has already confirmed that the incident was not linked to the variability of wind power, a clean, renewable energy source that the government is investing in as we work towards becoming a net zero emissions economy by 2050,” Leadsom said.
“Friday’s incident does, however, demonstrate the need to have a diverse energy mix.”
The emergency committee’s first meeting since the blackout took place on Monday between officials from the government and the regulator as well as energy industry professionals.
The investigation is likely to raise questions over standards agreed between Ofgem and National Grid that govern how the energy system is managed, as well as the role of regional network operators in keeping the lights on.
Meanwhile, National Grid is “urgently reviewing” what happened to trigger the outage, which caused “significant chaos and disruption to hundreds of thousands of people”, Leadsom said.
The energy regulator has demanded an interim report this Friday before a full technical explanation of the nationwide outage by early September.
John Pettigrew, National Grid’s chief executive, used his first interview since the blackout to blame regional network operators for making the rare outage more severe. He told the Financial Times that the investigation should look into why the networks allowed power to be cut to critical infrastructure such as railways and hospitals.
National Grid has said that the rare blackout was caused by a sudden drop in the energy system’s frequency – or energy intensity – after two unexpected generation outages within minutes of each other.
In an interview with BBC Radio 4, Pettigrew denied that the grid’s frequency had fallen to dangerously low levels with increasing regularity in the three months before the blackout.
The claim contradicts data from the system operator itself, which shows that the grid’s frequency fell to within 0.1% of its legal limits for the first time in years this summer.
To safeguard the energy grid, the industry regulator expects National Grid to keep the grid’s frequency at about 50Hz and no lower than 49.5Hz. The grid’s frequency fell to 49.55hz on 9 May, 49.52Hz on 20 June and 49.58Hz on 11 July.
Energy industry sources and experts agree that the energy system has become more volatile in recent years.
Thomas Edwards, an analyst at the energy consultancy Cornwall Insight, said: “We’ve observed that the fluctuations in frequency are getting wider. Frequency levels are less clustered around 50Hz compared to three years ago and we can see a clear trend of higher volatility in the system.”