Electricity supplies are gradually being restored across parts of Spain and Portugal after a major power outage caused widespread disruption across the Iberian Peninsula on Monday.
The outage led to the suspension of subway services, rail operations, and shut down ATMs, traffic lights, phone networks, and internet services in both countries, as well as parts of France. Many residents have been warned to prepare for a night without power.
The Iberian Peninsula, home to around 60 million people, remains unclear as to how many have been directly affected.
Spain’s national grid operator, Red Eléctrica, confirmed that power had returned to parts of Catalonia, Andalusia, the Basque Country, and Castile and León by Monday evening.
Eduardo Prieto, head of operations at Red Eléctrica, described the incident as “exceptional and extraordinary”.
Teresa Ribera, the European Commission executive vice president overseeing clean energy, called it “one of the most serious episodes recorded in Europe in recent times”.
The cause of the outage remains under investigation, with authorities yet to determine a definitive explanation.
Possible Causes Under Investigation
Initial reports suggested the blackout might be linked to a rare atmospheric phenomenon known as “induced atmospheric vibration,” which can trigger anomalies in high-voltage power lines.
Portuguese energy company REN initially cited the possibility of these oscillations affecting synchronisation between interconnected European grids.
However, the company later denied this claim in Portuguese media.
Solomon Brown, professor of process and energy systems at the University of Sheffield, explained that an “induced atmospheric vibration” could shift local electromagnetic fields, potentially causing imbalances in power flow.
He noted that in extreme cases, operators might shut down the grid entirely and restore it in stages — a delicate and time-consuming process.
Brown added that Spain and Portugal’s grids are interconnected, helping to maintain a single European power network. However, during periods of stress, these networks may have to be operated separately before being brought back online.
Grid Fragility Highlighted
Other experts have pointed to the vulnerabilities of interconnected networks. Onyema Nduka, senior lecturer in power sustainability at the University of London, said that because many power plants are located far from major cities, failures can quickly cascade across a network.
Redundancy systems are usually in place to limit such effects, but restoring power is complex.
The specific restoration plan for the current outage has not yet been detailed, Nduka added.
Portuguese officials told the Associated Press that the technical problems appear to have originated outside of Portugal, though investigations continue.
Cyberattack Claims Denied
Speculation over a possible cyberattack was raised by Andalusian regional president Juanma Moreno, who urged citizens to remain cautious.
However, Spanish Prime Minister Pedro Sánchez, Portuguese Prime Minister Luís Montenegro, and European Council President António Costa all dismissed the cyberattack theory.
“Spain has mechanisms to deal with these types of situations,” Sánchez wrote on X (formerly Twitter), urging citizens to cooperate with authorities.
Portugal’s National Cybersecurity Centre also stated there was no evidence to suggest a cyberattack was involved.
Commenting on the situation, Taco Engelaar, managing director at energy infrastructure consultancy Neara, said that due to the high level of interconnection between national grids, a fault or attack would likely produce similar widespread effects.
