A power cut on Friday left nearly a million homes and businesses across England and Wales in the dark.
The incident threw road and rail networks into chaos, knocked out traffic lights and affected hospital services and airports.
Although power had been restored to around 900,000 customers by Saturday, issues with the rail network continued.
Consequences could include enforcement action
Ofgem said: “In any incident the priority is to get power restored to customers as quickly as possible. National Grid has now informed Ofgem that the system has been restored.
“However, Ofgem understands the frustration this power cut has caused consumers. Ofgem has asked for 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.”
Rare and unusual event
A National Grid Electricity System Operator spokesperson said: “We appreciate the disruption caused by yesterday’s power outage and investigations have continued overnight to better understand the situation.
“As the Electricity System Operator we do not generate power directly, but use the power made available by the industry to manage the system and balance supply and demand. 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 16.54pm. We are still working with the generators to understand what caused the generation to be lost.”
Hornsea One lost load
A spokesperson from Ørsted said: “Hornsea One lost load on Friday 9th August, around the same time as another generation source lost load. We are investigating the cause, working closely with National Grid System Operator, which balances the UK’s electricity system.”
Could battery storage have prevented it?
Anesco Executive Chairman, Steve Shine said: “It would be easy for National Grid to write this incident off as a fluke event, but they have actually been aware of this potential issue for many years. Indeed, it can be seen in their System Operability Framework publications and was referenced in their System Needs and Product Strategy document.
“What is needed is a greater volume of faster response services, which can be called into action when the frequency drops. This would have prevented the need to turn the power off. Storage assets like our own 6MW Clayhill site responded to the event, but the fact is an insufficient volume of such assets have been procured.”
More flexibility is a must
Jonathan Ainley, Head of Public Affairs and UK Programme Manager at KiWi Power, said: “Friday’s power outages were caused by the almost simultaneous failure of two large plants. Whilst time will rightly be spent assessing the response to this incident and what could have been done to minimise its impact, there’s no doubt that National Grid needs more tools at its disposal to help manage supply and demand.
“As the UK continues its net zero carbon transition creating a smarter, more flexible energy system with widespread deployment of energy storage and demand side response is a must. Our own portfolio of distributed energy assets responded in real-time, reducing demand and exporting stored energy to help mitigate the shortfall in supply and stabilise the grid. Rapidly scaling these technologies requires competitive markets that provide a level playing field for new technologies to complete with incumbent generation and a regulatory regime that incentivises low carbon solutions.”