National Grid had evidence that the shift to renewable energy was putting Britain’s electricity supply at risk months before the biggest blackout in a decade, The Mail on Sunday can reveal.
The company, which is responsible for keeping the lights on, has downplayed the role of wind energy in the power cut that caused widespread chaos earlier this month.
John Pettigrew, chief executive of the FTSE 100 firm, described the outage as a ‘once-in-30-years’ event and said there was ‘nothing to indicate there is anything to do with the fact that we are moving to more wind or more solar’.
Yet in April, National Grid published research warning that using more renewable power sources posed a threat to the network’s ‘stability’.
In a report based on a £6.8 million research project, National Grid admitted that renewables increased the ‘unpredictability and volatility’ of the power supply which ‘could lead to faults on the electricity network’.
The revelations come as energy regulator Ofgem and the Government continue to investigate the causes of the blackout.
A report due out this week is expected to show the outage was caused by a series of failures, including a lightning strike which led to the almost simultaneous shutdown of two power stations.
A gas-fired power station at Little Barford, Bedfordshire, and the Hornsea offshore wind farm in the North Sea both went offline just before 5pm on August 9.
That caused the electricity network’s frequency – the rate at which power is transmitted to users – to drop below 50 Hz. Equipment can be damaged if it is higher or lower than this level.
To maintain frequency, local distribution networks were forced to cut supply in some areas.
Figures from the National Grid show almost half the UK’s power was generated from wind at one point on the day the power failed.