There was enough power for Heathrow to remain open during the entire period it was shut down on Friday, the head of National Grid has said.
Speaking for the first time since a fire forced North Hyde substation to close, the National Grid chief executive, John Pettigrew, said two other substations that serve Heathrow were working and could have supplied the airport with all the power it needed to remain open.
“There was no lack of capacity from the substations,” he told the Financial Times. “Each substation individually can provide enough power to Heathrow.”
The government has ordered an investigation into the closure of the airport, which returned to normal business on Sunday. The shutdown is estimated to have cost the airline industry £60m to £70m and disrupted the journeys of more than 200,000 passengers around the world.
Ed Miliband, the energy secretary, said the government was “determined to properly understand what happened and what lessons need to be learned”, in regard to the incident at Heathrow and the UK’s “energy resilience for critical national infrastructure”.
Over the weekend, Heathrow airport’s chief executive, Thomas Woldbye, defended the airport’s response to the unprecedented power outage: “Heathrow uses as much energy as a city every single day so we don’t have backup power for baggage systems, fuel systems, things like air bridges and so on.
“So whereas the safety systems are working and we can get aircraft in and out, most of the airport infrastructure comes to a standstill when we need to reset, as we did [on Friday].”
But Pettigrew said two substations were “always available for the distribution network companies and Heathrow to take power”. He added it was a “question for Heathrow” as to why it took the action it did.
“Losing a substation is a unique event – but there were two others available,” he said. “So that is a level of resilience.”
On the day of the fire, Woldbye said the airport’s backup systems “worked the way they should” and told reporters outside the airport that the power supply of Heathrow is a “bit of a weak point”.
The next day he told the BBC that although the airport has other substations “to switch to them takes time”, and he was proud of how Heathrow workers had responded to the fire. “The situation was not created at Heathrow airport and we had to deal with the consequences,” he said.
“I don’t know of an airport that has backup supply that can switch on in minutes to the magnitude of what we experienced yesterday. The same would happen in other airports.”
Pettigrew said all three transformers at the North Hyde substation were damaged by the fire, which firefighters have said burned 25,000 litres of cooling oil. This included one transformer that is a backup and is located further away from the other two.
He added that the cause of the fire was not yet known, as the site is still too hot for full forensic work, and third-party involvement is not ruled out. “I can’t remember a transformer failing like this in my 30-plus years in industry,” Pettigrew said.
Counter-terrorism officers from the Metropolitan police initially led the investigation, but the force said the fire was not believed to be suspicious. London fire brigade is now leading the inquiry, which will focus on the electrical distribution equipment.
Asked why the North Hayes site, built in the 1960s, was designed in a way that meant a single fire could knock out all three transformers, he said: “You have to build substations in the space available, and obviously you do all you can to mitigate the risks.
“But that is something that clearly I think an investigation will look into a bit further.”
