National Grid has blamed a lightning strike for Britain’s biggest blackout in more than a decade after it caused two power generators to trip offline.
The lightning strike was one of many to hit the grid on the same day as the 9 August blackouts but in an “extremely rare and unexpected event” it managed to bring down two electricity generators more than 100 miles apart.
The report revealed that National Grid was unable to cover the twin outages at a gas-fired power plant in Bedfordshire and an offshore wind farm off the east coast of England because it did not have enough backup.
The outages took place within seconds of each other immediately after the strike, according to the report, causing chaos across much of England and Wales.
The combined power capacity lost in the outages was more than 1,300MW and National Grid had only 1,000MW in reserve when the outages took place.
The energy regulator has responded by launching an investigation into whether National Grid’s statutory requirements, which are set by Ofgem, require it to hold enough reserve electricity supplies to stabilise the grid following outages.
The Guardian revealed that National Grid has suffered three blackout “near misses” in as many months after similar-sized outages in May, June and July, which were all greater than 1,000MW.
It will also investigate whether the energy generators and regional energy networks responded correctly to the sudden loss in frequency caused by the power plant trips.
Jonathan Brearley, a senior executive at Ofgem, said the regulator has received the report and believes “there are still areas” that need to be investigated.
“This will ensure the industry learns the relevant lessons and to clearly establish whether any firm breached their obligations to deliver secure power supplies to consumers,” he said.
“The power cuts of Friday 9 August caused interruptions to consumers’ energy and significant disruption to commuters. It’s important that the industry takes all possible steps to prevent this happening again.”