Heathrow Airport fireplace defined from ‘small city’ substation to why there isn’t any again up
Experts have weighed in on the likely ways the fire at a substation near Heathrow Airport could have started, and offered insight into possible backups and systems in place to keep the airport running
The North Hyde Electricity Substation sits up a non nondescript road just off the Bull’s Bridge roundabout in West London.
The road it public, opposite the newly-built Segro business park, and is completely visible from the road and separated only from it by a pair of metal fences, one of which is waist height.
It was a fire here that has led to flights around the world being cancelled, and some jets over the Atlantic reportedly turning 180degrees and heading for home.
It seems bizarre that such a small, unassuming spot most wouldn’t even notice, would create such an incident. Dr Komal Raj Aryal, Lecturer in Crisis and Disaster Management, Aston University, put things succinctly when he said it, “highlights how a localised disruption to one of the UK’s critical infrastructures can trigger cascading impacts across the globe.”
What happened in the fire at Heathrow and how was it possible?
Prof Rory Hadden, Chair of Fire Science at the University of Edinburgh, said: “The fire appears to have been in a transformer at the substation. Transformers are electrical equipment in the power distribution network and are often filled with oil as a coolant. Although oils are flammable their use is common in these installations because they do not conduct electricity so can be used effectively to cool the electrical components.
“Although there are strict precautions to minimise the risk of a fire – the use of low flammability (high flashpoint) oils, containment in the event that there are leaks, and potentially even automatic fire suppression systems – the risk of fire in these installations remains real as there are large amounts of electrical energy around which could, usually when more than one thing foes wrong, cause a fire.”
What is an electrical substation?
Dr Paul Cuffe, Assistant Professor, UCD School of Electrical & Electronic Engineering at University College Dublin, said: “A substation is where different power lines link together; like a junction on a motorway network.
“Substations house large electrical transformers that interlink power lines that operate at distinct voltage different voltages: most of the UK’s transmission lines operate at either 400,000 Volts or 275,000 Volts.
“These high voltage power lines function to transport bulk electrical power around the country. In most substations, there will also be transformers that step down to yet lower voltages; these withdraw power from the national grid for distribution out to the surrounding region at lower voltage levels; typically at 66,000 Volts or 33,000 Volts.
“Substations also house a lot of sophisticated switching equipment, to allow lines and transformers to be turned on and off to allow maintenance or to reconfigure the network in emergencies.
“It is not overtly abnormal; we can anticipate that, from time to time, substation equipment will fail and downstream power outages will result.”
Why would there only be one substation at Heathrow?
“One could argue that a critical piece of national infrastructure like Heathrow deserves special grid connection arrangements to secure its supply of electricity further,” Dr Cuffe said. “For instance, sometimes critical loads like this are fed from two separate substations to provide redundancy when outages happen. I am not familiar with the exact connection arrangements for Heathrow airport but neither setup would surprise me.
“It is ultimately a political and economic question to determine the right level of capital investment into grid infrastructure to avoid the problems that outages like this cause. Redundant power supplies for an airport the size of Heathrow do not come free!
“An airport like Heathrow requires a lot of electricity to operate; equivalent to a large town. As such, it would be typical for an airport like Heathrow to be given a dedicated connection from the substation at Hayes; there is likely a dedicated power line and transformer there that connects the airport to the wider grid. When a major fire severs that link, it will no longer be possible to bring bulk electricity to the airport.
“I would anticipate that a major airport like Heathrow would have some on-site emergency capability to ride through a grid disturbance; I would hope that the traffic control tower and runway lights weren’t totally plunged into darkness!
“However, processing planeloads of passengers requires Heathrow in its totality to consume a town’s worth of electricity, and the inability to meet this requirement is likely why flights had to be cancelled.”
Speaking on BBC Radio 4’s Today Programme, Energy Secretary Ed Milliband said, “There’s obviously been a catastrophic fire at this substation. It appears to have knocked out a back-up generator as well as a substation itself.”
A National Grid spokesman said: “A fire at our North Hyde substation in west London has damaged equipment, leading to a loss of power supply in the area. We are working at speed to restore power supplies as quickly as possible.
“We are working alongside the DNO [distribution network operator] for the area, SSEN, to reconnect affected domestic customers. As of 0600, power has been restored to 62,000 customers, with 4,900 currently without power. Restoration efforts will continue this morning, and further updates will be provided.”
