National Grid say lightning was to blame for the failure at a Little Barford Power Plant that resulted in Britain’s largest blackout in over 10 years.
The blackout at around 5pm on 9 August, affected large parts of England and Wales leaving commuters stranded, road signals unable to function, and a hospital and airport without power.
1.1 million electricity customers were also without power for up to an hour.
Now a report from National Grid has blamed a lightning strike on the grid between Eaton Socon and Wymondley.
This resulted in the “extremely rare and unexpected event” of ‘tripping’ the Little Barford plant and another over 100 miles away.
The National Grid was unable to cover both outages as it only had 1,000MW in reserve. The loss of power at both stations was equivalent to more than 1,300MW.
Outages at Little Barford, a gas fired power station, and the Hornsea off-shore wind farm happened within seconds of each other immediately after a lightning strike.
The strike may also have created a cascade of failures at a number of small-scale power sources, such as those powered by renewable energy and diesel farms, which could have supplied 500MW.
Ofgem say they’re now investigating to see if the statutory requirements they set National Grid require them to hold enough reserve power to stabilise the grid after a power station failure.
“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,” said Jonathan Brearley, Ofgem’s Executive Director of Systems and Networks.
The opening of this investigation does not imply that Ofgem has made any findings about non-compliance for any of the companies mentioned at this early stage of the investigation. However, if evidence does emerge in the course of the investigation enforcement action could follow.
They are also investigating if the energy generators and regional energy networks responded appropriately to the power plant’s shutting down.
The Office of Rail and Road, who regulate the railways, will also be consulted to determine why the drop in power led to such disruption for passengers and if it could be avoided.
Jonathan added: “Having now received National Grid ESO’s interim report, we believe there are still areas where we need to use our statutory powers to investigate these outages.
“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.”
A final detailed technical report into the outages by National Grid will be submitted to Ofgem by 6 September. You can read the interim report here.