Spain, Portugal switch back on and search for answers after major blackout

Spain and Portugal switched their power back on after the worst blackout in their history, though authorities offered little explanation for what had caused it or how they would prevent it from happening again.

Traffic lights were back on, train and metro services slowly returned and schools reopened. Commuters battled with delays to get back to work after an outage that had left people stranded in lifts and cut off from phone contact with their families.

The sudden outage had seen the equivalent of 60 per cent of demand in Spain drop in five seconds around midday on Monday.

Spanish Grid operator REE on Tuesday ruled out a cyber attack as the cause. It said it had identified two incidents of power generation loss, probably from solar plants, in Spain’s southwest that caused instability in the electric system and led to a breakdown of its interconnection with France.

But it was still too early to explain why that had happened, REE's system operations chief Eduardo Prieto told a press conference.

"Until we receive the data on the generation aspects we cannot draw conclusions," he said. REE planned to invest in more interconnections with France to make the system more stable, he added.

Spain is one of Europe's biggest producers of renewable energy, and the blackout sparked debate about whether the volatility of supply from solar or wind made its power systems more vulnerable.

Investment bank RBC said the economic cost of the blackout could range between 2.25 billion euros and 4.5 billion euros, blaming the Spanish government for being too complacent about infrastructure in a system dependent on solar power with little battery storage.

STATE OF EMERGENCY

Madrid's authorities put on free buses to get people to work on Tuesday and the metro and some trains started to operate, although with delays.

A state of emergency was declared across many Spanish regions on Monday, with the deployment of 30,000 police. In Atocha station in Madrid, police and Red Cross workers handed out blankets and bottles of water. Cafes and restaurants counted the cost of lost produce after fridges and freezers were switched off for more than eight hours.

In Portugal, the government said hospitals were back up and running, airports were operational albeit with delays in Lisbon, while the capital's metro was restarting operations and trains were running.

Energy systems can be vulnerable when combining intermittent renewable power such as wind and solar with traditional sources such as gas and nuclear plants, said Victor Becerra, a professor of power systems engineering at the University of Portsmouth.

"Whatever the cause, a major failure in one area can place sudden pressure on neighbouring systems, causing protective shutdowns to prevent further damage," Becerra said.

More than 75 per cent of the energy Spain was using at the time of the outage came from renewable sources, according to Red Electrica data.