Passengers wait for their trains at Atocha station in Madrid on April 29, 2025, the day after a massive power cut affecting the entire Iberian peninsula and the south of France. | Photo by Thomas COEX / AFP
Madrid, Spain – A massive power outage hit Spain and Portugal on Monday, cutting telephone and internet access, halting public transport and plunging cities into darkness.
What happened?
The outage, which began at 1033 GMT (12:33 pm in Spain and 11:33 am in Portugal), affected all of the Iberian Peninsula, which is home to around 55 million people, as well as parts of France.
Spain’s Canary Islands in the Atlantic Ocean and its Balearic Islands in the Mediterranean Sea, as well as the Spanish exclaves of Ceuta and Melilla in North Africa, were spared.
These regions have little or no electrical connections to the Iberian Peninsula and their power systems operate independently.
READ: Power returns to most of Spain, Portugal after massive blackout
Why did it last so long?
In France, electricity network operator RTE quickly restored power. In Spain and Portugal, however, it took much longer to get the power back on, with some residents waiting up to 20 hours.
One explanation lies in the scale of the blackout, which according to the Spanish grid operator REE began with a “strong oscillation in power flows” on the electricity network “accompanied by a very significant loss of production” — a phenomenon it described as “totally extraordinary”.
“This loss of production exceeded the reference disturbance for which electricity systems are designed” and led to “a disconnection of the peninsular electricity system” from the rest of the EU, with the Spanish network “collapsing” in the space of just five seconds, according to REE.
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Power stations, including nuclear ones, stopped working in response to this blackout.
The transmission lines had to be “gradually reactivated and the production units synchronised”, which is “time-consuming and technically arduous”, said Pratheeksha Ramdas, an analyst at Rystad Energy.
Another explanation for the slow recovery is the nature of the Iberian Peninsula’s energy grid, which operates as an energy island and is linked to the rest of Europe through a small number of cross-border interconnections with France.
Spain also has a limited energy storage capacity which “restricts its ability to absorb these fluctuations and slows down the rapid recovery needed during major blackouts”, said Ramdas.
What is the possible cause?
Several hypotheses have been put forward, including that of a cyberattack.
Spain’s top criminal court said Tuesday it was investigating whether the blackout was “an act of computer sabotage on critical infrastructure” that could be classified as “a terrorism offence”.
But REE’s director of operations, Eduardo Prieto, ruled out “a cybersecurity incident”, telling a news conference “there was no type of intrusion” in the company’s control systems that may have caused the outage.
Stories spread on social media based on a fake press release attributed to Portuguese grid operator REN which said a “rare atmospheric phenomenon” could have caused a “fault” in the system. This too has been ruled out.
“No unusual meteorological or atmospheric phenomena have been detected,” Spain’s national weather agency AEMET said.
Spanish Prime Minister Pedro Sanchez urged people “not to speculate” and announced that his government had set up a commission to investigate what triggered the incident. He refused to rule out any hypothesis.
Prieto said the grid operator was still gathering key information which will provide a “complete picture” and “obtain the appropriate conclusions”.
