Everything that is known and what remains to be clarified about the great blackout: causes, hypotheses and restoration of supply

Spain has experienced one of the worst power outages in its recent history. In just five seconds, at 12:33 p.m. on Monday, April 28, 60% of the country’s electricity generation suddenly disappeared.

Millions of citizens, from Madrid to Galicia and  Aragon , suffered the consequences of an unprecedented “energy blackout ,” which left almost the entire peninsula without power and plunged public transportation, communications, and essential services into chaos. To this day, the exact cause of this collapse remains unknown.

THE BLACKOUT: HOW IT BEGAN AND ITS INITIAL IMPACT

According to Red Eléctrica de España (REE), the outage occurred after a “very sharp fluctuation in power flows” in the electrical grid. This sudden loss of 15 gigawatts of generation , equivalent to 60% of national demand at the time, caused an automatic disconnection of the peninsular electrical system from the rest of Europe , triggering a total blackout in Spain, Portugal, and parts of southern France.

The recovery was gradual : northern areas such as the Basque Country and Galicia began to recover power at 2:00 p.m., while regions such as Madrid , the Valencian Community , and Andalusia took several more hours. At 6:00 a.m. this Tuesday, Red Eléctrica reported that 99% of electricity demand had been restored .

WHAT CAUSED THE BLACKOUT: THE HYPOTHESES UNDER INVESTIGATION

So far, there is no official explanation for the cause of the system crash. The government insists that “no hypothesis has been ruled out ,” but urges everyone to avoid spreading rumors and misinformation .

Among the theories that have circulated are:

• Meteorological phenomenon : Initially, a possible “induced atmospheric vibration” was suggested as the cause, but official sources quickly denied this version.
• Cyberattack : Speculation of a cyberattack arose after “unusual activity” was detected in North Africa days earlier , according to the National Intelligence Agency (CNI). However, European Commission Vice President Teresa Ribera stated that there is “no evidence of sabotage” so far.
• Other technical causes : Experts warn that incidents of this magnitude could also be due to serious technical failures , not necessarily malicious attacks.

“15 GIGWATTS LOST IN THREE SECONDS”

Prime Minister Pedro Sánchez appeared twice to report on the situation caused by the massive blackout that affected Spain. In his speech, he explained that at 12:33 p.m. on Monday, 15 gigawatts of electricity generation were suddenly lost , equivalent to 60% of national demand at the time. This sudden drop triggered the collapse of the peninsular electricity system .

Sánchez emphasized that such a “zero energy” situation has never occurred before in Spain, underscoring the unprecedented and exceptional nature of the incident. He also noted that all hypotheses regarding the cause of the blackout remain open and are being investigated “with the utmost caution,” avoiding jumping to conclusions for now.

The president also asked the public not to spread information of dubious origin, in order to avoid increasing social alarm at a time of extreme sensitivity. He noted that the National Security Council and the country’s main emergency agencies are working in a coordinated manner to clarify what happened and guarantee the safety of citizens.

Regarding the restoration of electricity service, Sánchez explained that the system has been gradually restored, although he acknowledged that the impact has been uneven across the different autonomous communities. Finally, he insisted that Spain is “a safe and responsible country” and appealed for the calm and cooperation of all citizens while the investigations continue.

HOW SUPPLY WAS RESTORED AND WHICH AREAS ARE STILL AFFECTED

The recovery of the electrical system was gradual and uneven. The Basque Country, Galicia , and parts of Catalonia were among the first to recover power. By Monday afternoon, other regions began to join in, including Madrid , Valencia , Castilla-La Mancha , and Murcia.

However, despite the fact that 99% of demand has recovered , public transport remains affected . Renfe has reported that commuter and medium-distance services in cities such as Madrid , Seville, Valencia, and Zaragoza are experiencing disruptions. Some high-speed trains have also experienced delays, especially on connections with Andalusia and Galicia.

Airports, for their part, operated using emergency generators , but also recorded flight delays of up to two hours .

WHY IT DIDN’T AFFECT THE BALEARIC ISLANDS, THE CANARY ISLANDS, CEUTA AND MELILLA

These territories were spared the blackout because their power grid is separate from the mainland’s system and relies on their own island infrastructure. In the case of the Balearic Islands, the connection to the mainland is via a submarine cable, but the system is capable of self-sufficiency. The Canary Islands, Ceuta, and Melilla also operate with independent systems, which allowed them to maintain stability.

The historic blackout that paralyzed Spain still leaves more questions than answers. With power almost restored across the country, the technical investigation remains open, and authorities insist on proceeding with caution in the absence of a confirmed cause. Spain, for now, remains on alert, awaiting clarification of one of the largest electrical incidents in its history.