Britain’s energy market regulator has threatened National Grid with a possible fine after nearly a million businesses and homes in England and Wales suffered power cuts on Friday evening, causing severe disruption to transport at the start of the weekend getaway.
Ofgem said it had demanded an urgent detailed report from National Grid “so we can understand what went wrong and decide what further steps need to be taken”. This could include enforcement action, the regulator added.
Ofgem has the power to fine energy companies up to 10 per cent of their turnover if they are found to have been at fault.
National Grid said on Saturday morning that investigations had been working overnight to better understand the situation but insisted the “root cause of yesterday’s issue was not with our system but was a rare and unusual event, the almost simultaneous loss of two large generators, one gas and one offshore wind, at 16:54”.
It added: “We are still working with the generators to understand what caused the generation to be lost.”
Energy analysts at EnAppSys had previously identified the Little Barford gas-fired power station in Cambridgeshire, owned by the German power company RWE, and the Hornsea offshore wind farm, owned by Danish utility Orsted, as the cause of the outage.
National Grid said other generators had increased their output to compensate for the loss in supply.
“However due to the scale of the generation losses this was not sufficient, and to protect the network and ensure restoration to normal operation could be completed as quickly as possible, a back-up protection system was triggered which disconnects selected demand across GB,” National Grid added.
RWE said its Little Barford site had experienced a technical fault on Friday afternoon, but was back in action and ready to be called upon by National Grid to generate power later that night.
Such technical faults are not uncommon but it is quite rare for two generators to trip at the same time and cause blackouts. Gareth Miller, chief executive of Cornwall Insight, a consultancy, said on Twitter that the last time two power stations failed at the same time was in 2008, when hundreds of thousands of homes in England lost power.
The power outages reported across the South-east, Midlands, South-west, North-east and Wales left hundreds of people trapped on trains. The power cuts also disrupted traffic lights in areas of London and the South-east as well as essential services such as hospitals.