Electricity supplies are slowly coming back to some parts of Spain and Portugal as a major power outage on Monday caused chaos for those living across the Iberian Peninsula.
The outage halted subway trains and railways, cut phone service and Internet connections, and shut down ATM machines and traffic lights throughout booth countries and parts of France. Many now face the prospect of a night without power.
The Iberian region is home to a population of roughly 60 million people, though it's not clear how many have been affected by the outage.
Red Electrica, Spain's national grid operator, said in a statement that power supplies had been restored to parts of several regions, including Catalonia, Andalucia, the Basque Country, and Castille and Leon on Monday evening.
Eduardo Prieto, the head of operations at Red Eletrica, told the Associated Press that the situation was unprecedented, calling the event "exceptional and extraordinary," while Teresa Ribera, European Commission executive vice president tasked with promoting clean energy, called the incident "one of the most serious episodes recorded in Europe in recent times".
Authorities are still seeking to determine the exact cause of the outage, but experts have floated some possible scenarios for why it occurred.
It should be noted, however, that there is little evidence at present to say definitively what went wrong.
Rare atmospheric phenomenon?
Reports circulating on Monday suggested that the outage could have been the result of a rare phenomenon called "induced atmosphere vibration," which caused "anomalous oscillations" in the high-voltage lines of Spain’s energy grid.
"These oscillations caused synchronisation failures between the electrical systems, leading to successive disturbances across the interconnected European networks," Portuguese energy company REN reportedly told the BBC on Monday afternoon.
REN later refuted these claims in the Portuguese media. But what are these vibrations, and what effect would they have had on the region’s power grid?
Solomon Brown, a professor of process and energy systems at the University of Sheffield in the UK, said that an "induced atmospheric vibration" could be considered the equivalent of "inducing a small shift in the local electromagnetic field".
"This would have the same kind of impact as, say, a solar event and may cause imbalances in electrical power flows that would need to be controlled," he told Euronews Next.
The power distributor could use a range of actions to control this, he continued, like asking power sources to produce or reduce the amount of power they’re providing.
In cases where the disturbance is too great, Brown continued, operators may shut the grid down and slowly turn it back on. Re-energising the grid is "tricky," he added, saying it may take a number of hours for the power to come back on everywhere.
While not an expert on the Spanish-Portuguese grid, Brown believes the two are "interconnected" through high-voltage cables that are synchronised to create a single power network.
"This is quite common and for Europe, helps to create a single power network that can cooperate, but at times of stress have to be managed separately and brought back together," he said.
Possible grid issues
Onyema Nduka, a senior lecturer in power sustainability at the University of London, said that power networks are normally interconnected because the generation plants that power them are located far away from the cities.
That means that a power cut in one part of the grid could "lead to a cascading effect in other areas".
"Ideally, redundancies are built into the system, such as having multiple supply points, backup generators sited at different locations, interconnected wires and cables etc," he said.
The solution is for energy companies to restore electricity to the affected customers as soon as possible, but the procedure for completing this feat "has not yet been revealed," Nduka added.
Portuguese officials quoted by the AP and local media have so far blamed the outage on unspecified technical issues that stem from outside the country, but noted that the investigation is still ongoing.
Cyberattack ruled out by some, not all
Juanma Moreno, president of the Andalusian regional government, said on Monday that a cyberattack has not been ruled out and advised citizens to be cautious.
However, the cyberattack claim has been refuted by officials, including Pedro Sanchez, Spain’s premier, Luis Montenegro, Portugal’s prime minister, and Antonio Costa, the president of the European Council.
"Spain has mechanisms to deal with these types of situations," Sanchez posted on social media platform X.
"Once again, I appeal to the public to cooperate with all authorities and act responsibly and civilly, as we have always done".
The Portuguese National Cybersecurity Centre also said in a statement that there was no indication the outage was due to a cyberattack.
In comments to Euronews, Taco Engelaar, managing director at energy infrastructure experts Neara, posited that the interconnectivity of the national grids and their systems would mean a fault or attack would have the same net result.
"Such a widespread grid failure is extremely unusual and could be caused by a number of things: there could be a physical fault in the grid which brings down power, a coordinated cyberattack could be behind it, or a dramatic imbalance between demand and supply has tipped the grid system over the edge," he said.
"If it's a system fault, then the interconnectivity between different regional and national grids could be leading to the large footprint of outages we're seeing today [Monday]," he added.
"The same goes for a cyberattack - lots of these systems are connected and share assets - taking down one could take down many".
