Anesco has called for the electricity system operator (ESO) at National Grid to procure more back-up generation to prevent a repeat of the power cut on Friday that brought much of the transport networks to a standstill during the evening rush hour.
The renewable developer, which is also building a large portfolio of battery storage, said blame for the blackout “lies squarely” with the ESO for failing to procure enough frequency response to cover the simultaneous loss of two generators.
“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,” said Anesco executive chairman Steve Shine.
“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.”
The ESO was forced to cut power supplies to around a million customers after two generators went offline in quick succession – first, RWE’s 730MW Little Barford combined-cycle gas turbine plant in Bedfordshire shortly before 5pm, and then two thirds of Orsted’s 1.2GW Hornsea Two offshore windfarm a few minutes later.
In this short space of time, almost 1.5GW of generation was lost from the transmission network.
“Fault here doesn’t lie with the generators or the timing of the failures,” said Shine.
“The power cut and resultant cost to business and industry, lies squarely at the door of National Grid who failed to take appropriate preventative action and we await with interest the results of Ofgem’s investigation.”
Anesco asset management director Mike Ryan said: “What was interesting about this event was the role that battery storage ended up playing. Anesco’s own Clayhill batteries fully responded to help catch the falling frequency.
“When National Grid cut off the power, the frequency bounced back very quickly, sending the system the other way and meaning our battery sites were then called on to balance the grid by taking power out.”
Shine said the power cut could have been avoided if there were more batteries available to contain the initial drop in frequency.
“Despite everyone knowing how important they are to the system, and promises being made about tariffs that would make batteries investible, it’s 18 months later and we are still waiting,” he added.
“It’s incredibly frustrating and if something isn’t done, it will be the end of batteries – as no one will build them and no investor will touch them.”
However, Cornwall Insights’ senior consultant Thomas Edwards questioned whether the additional cost would be justified given the rarity of large simultaneous generation losses.
“I’m not clear that it is necessarily worth preventing this kind of issue,” he told Utility Week.
“It would be a significant extra cost and a lot of the problems that occurred were due to the inability of the rail network to cope with a loss of power. Everything was back online within 40 minutes.
“If you were to cover the whole of the largest infeed loss requirement with a sub-one-second frequency response service; if you were to cost that based on the recent enhance frequency response tenders, you would have been looking at probably £500 million.
“Do you want spend another half a billion pounds every year?”
Edwards said the 40-minute power cut fell within the government’s security of supply standard, which underpins the operation of the capacity market and limits supply interruptions to no more than three hours per year.
“Would it better to increase the resilience of things like traffic and rail networks; make sure hospital backup generators work; make sure airport backup generators work; focus more on the other parts of the integrated economy?”, he asked. “Or do you want to spend a lot more money on providing a lot more backup?”
Edwards said the ESO is working hard to overhaul its operations as the growth of renewables makes the power grid more susceptible to sudden changes in frequency. It could do more to prevent problems like this occurring, for instance, by integrating wind generation into balancing service more quickly.
But, he concluded: “Sometimes stuff breaks. We have all these standards that are set in place. Everything worked as it was supposed to. I guess now the debate is: are those the right standards?”
National Grid chief executive John Pettigrew said in statement: “Whilst this event was due to a rare and exceptional combination of circumstances, we were able to restore power within 15 minutes.
“The system did the job that it was designed to do – by protecting many more millions of customers nationwide from potential loss of power. Our own customers, the DNOs, had all restored power to their own customers within 45 minutes.
“We don’t underestimate the inconvenience and disruption this caused however, and one of the questions we will be addressing as an industry is whether the system as it is currently designed prioritises power supplies in the right way.”
National Grid Group chief executive John Pettigrew said in statement: “Whilst this event was due to a rare and exceptional combination of circumstances, we were able to restore power within 15 minutes.
“The system did the job that it was designed to do – by protecting many more millions of customers nationwide from potential loss of power. Our own customers, the DNOs, had all restored power to their own customers within 45 minutes.
“We don’t underestimate the inconvenience and disruption this caused however, and one of the questions we will be addressing as an industry is whether the system as it is currently designed prioritises power supplies in the right way.”
Business and energy secretary Andrea Leadsom has said the government will commission the Energy Emergencies Executive Committee to conduct an investigation into the power cut.
Meanwhile, Ofgem has requested a “detailed report” from the ESO to establish “what went wrong and decide what further steps need to be taken”. The regulator said these steps “could include enforcement action.”