Large-scale power outages in Spain and Portugal: A grid crisis amid the pains of the energy transition

On April 28, 2025, Spain and Portugal suffered the most severe power grid collapse in Europe in nearly two decades. The blackout, which lasted over 11 hours, plunged more than 50 million people on the Iberian Peninsula into chaos and affected neighboring regions such as southern France, Morocco, and Andorra. This incident not only exposed the deep-seated contradictions in Europe's energy transition but also prompted a global re-examination of grid stability.

I. A Complex Web of Causes Leading to the Grid Collapse

The immediate trigger of the blackout was attributed to the "strong oscillation" phenomenon in the power grid. Data from Red Electrica, the Spanish grid operator, showed that at 12:35 on the day of the blackout, the national grid load dropped by 15 gigawatts within five seconds, equivalent to an instantaneous loss of 60% of the generation capacity. This extreme fluctuation triggered a chain reaction, causing the separation of the Spanish grid from the European mainland grid and leaving the Iberian Peninsula in an isolated power island state.

The combination of meteorological conditions and the vulnerability of the grid was a key factor. REN, the Portuguese grid operator, proposed the "atmospheric-induced vibration" hypothesis, suggesting that abnormal temperature fluctuations in southern Spain on that day caused severe oscillations in 400-kilovolt ultra-high voltage lines. This physical phenomenon led to resonance between the transmission lines and the towers, eventually causing the separation. Meteorological records showed that the temperature in Seville, Spain, rose by 8°C within 15 minutes two hours before the blackout, which may have exacerbated the thermal expansion and contraction effect of the cables, reducing transmission efficiency.

The deeper structural contradiction lies in the imbalance of the energy transition. Spain's share of renewable energy has reached 43%, but the grid's peak load regulation capacity has not improved in tandem. At the time of the incident, Spanish nuclear power plants automatically shut down for safety reasons, further weakening the grid's inertia. The combination of "excessive share of wind and solar power + insufficient energy storage" made the grid highly vulnerable to collapse during sudden load changes. Energy expert Mark Nelson pointed out that low-inertia grids are extremely sensitive to small disturbances, and this incident was an extreme manifestation of the imbalance between supply and demand.

II. Social Paralysis under the Butterfly Effect

The transportation system was the first to fall into chaos. Data from the Spanish National Railway Company showed that 116 trains carrying 35,000 passengers were affected by the power outage. The Madrid Metro evacuated over 200,000 people in a single day. Lisbon Airport canceled 40% of its flights due to power failure in the boarding bridges, and the air traffic control system at Madrid Barajas Airport partially broke down, causing delays for about 200 international flights. The failure of traffic lights led to a sharp increase in traffic accidents. In the Madrid region alone, 37 collisions were recorded due to traffic light malfunctions.

The communication network was severely damaged. Cloudflare's monitoring showed that internet traffic in Portugal dropped by 30%, and in Spain by 37%. A large number of mobile communication base stations went offline. People were forced to rely on radios for information, and the topic of a "dark age" was widely discussed on social media. The financial system experienced temporary chaos. Some ATMs in Madrid banks were out of service, and the electronic payment system was paralyzed for more than four hours.

The medical system faced a life-and-death test. The Spanish Ministry of Health disclosed that 12 hospitals activated emergency diesel generators to maintain the operation of operating rooms, but 37 emergency surgeries were still postponed. The automatic drug dispensing systems in pharmacies broke down, and some critically ill patients had to be manually prescribed medication. Even more seriously, the backup power supply in nursing homes could only last for six hours, forcing a Lisbon institution to manually transfer 43 disabled elderly people.

III. Warning Lights for Global Energy Transition

The aftershocks of this power outage have yet to subside. The Spanish government declared a state of emergency, France rushed to provide 700 megawatts of electricity support, and Morocco also activated cross-border power transmission agreements. Economists estimate that Spain's tourism industry alone suffered a loss of 120 million euros in a single day, and the cancellation of flights at Lisbon Airport caused losses of over 8 million euros to the aviation industry.

This incident exposed three deep-seated vulnerabilities in the European power grid: first, the fragility of cross-border grid interconnections, with Spain and France connected by only four 400-kilovolt lines, with a transmission capacity far lower than the 2,000-kilowatt-level channels between Germany and Poland; second, the lag in energy storage facility construction, with Spain's energy storage capacity accounting for only 3% of its renewable energy generation, far below Germany's 15%; third, insufficient emergency response mechanisms, as the EU has yet to establish a cross-border grid coordination dispatch platform.

This crisis has sounded the alarm for global energy transition. The Spanish government has committed to investing 20 billion euros in the next five years to upgrade the power grid, with a focus on building pumped storage power stations and battery energy storage systems. The European Commission has announced the launch of the "Grid Resilience Plan," requiring member states to increase their grid investment from the current 0.8% of GDP to 1.5%. Energy experts warn that if the balance between the development of renewable energy and grid stability cannot be maintained, similar power outages may become the new normal.

As the lights gradually come back on across the Iberian Peninsula in the twilight, this power outage leaves the world not only with the physical task of grid repair but also with a profound reflection on the path of energy transition. In the game between climate goals and energy security, how to build a more resilient power system will become a question that humanity must answer in the 21st century.