A widespread blackout occurred in Spain around 12:30 hours. Later, it was confirmed that this blackout also affected other European countries. We review some possible causes that could generate an event like this.
What are the main technical causes that could lead to a general power outage in Spain and what would happen if there was a structural failure in the electricity transmission network?
The Spanish Electricity Grid manages high and very high voltage lines. A serious failure in a main substation, a critical line, or in the protection and control systems could destabilize the grid and trigger automatic blackouts. A similar example occurred in Chile in 2025, leaving the country without electricity for over eight hours.
How can a sudden imbalance between supply and demand cause a blackout?
The electrical system needs to constantly balance generation and consumption. If demand suddenly rises or generation unexpectedly drops, and quick action is not taken, the grid frequency can collapse, leading to massive disconnections, as happened in Italy in 2003, where a blackout paralyzed the peninsula for 12 hours.
What would be the consequences of the simultaneous interruption of several generation plants?
Although the system can withstand the loss of a generator, if several plants fail at the same time, such as nuclear or combined cycle plants, the reserve capacity could be exceeded, leaving entire areas without power. This occurred in Japan in 2011 after the earthquake and tsunami that shut down multiple plants.
Can a cyberattack cause a power outage?
Yes. The SCADA systems that control the electricity grid are vulnerable. A cyberattack that manipulates operations or paralyzes control centers can trigger imbalances and uncoordinated disconnections. In Ukraine, in 2015, a cyberattack left over 200,000 users without electricity. What risk does a failure in international interconnections pose? Spain depends on interconnections with France, Portugal, and Morocco. If these fail, the ability to import electricity in emergencies is limited, which could overload the internal grid. A similar failure in Germany in 2006 caused power outages that affected several countries, including northern Spain.
How does a rapid decrease in renewable generation affect?
The variability of wind or solar power can cause renewable production to drop abruptly. Without fast reserves or firm backup generation, the grid's stability is compromised. In Germany in 2017, an unexpected drop in wind generation jeopardized the supply, although a blackout was avoided.
Can human error cause a blackout?
Yes. Real-time operation of the electricity grid is very complex. Errors in generation dispatch or reserve activation can amplify small incidents to cause massive blackouts, as happened in the U.S. and Canada in 2003, affecting over 50 million people.
What would be the consequences of sabotage or physical damage to critical infrastructure?
An attack on substations, transformers, or control centers can disconnect strategic nodes and cause overloads that trigger cascading blackouts. In California in 2013, an armed attack severely damaged a substation, although a blackout was avoided thanks to a rapid response.
Can a failure elsewhere in Europe affect Spain?
Yes. Spain is integrated into the continental European electricity system. A serious failure in another country can spread through interconnections. In 2021, a failure in the Balkans affected all of Europe, requiring emergency maneuvers to prevent blackouts in Spain.
How can extreme weather events cause a blackout?
Phenomena like intense solar storms, which affect high-voltage lines, or extreme storms that damage electrical infrastructures and control systems, can severely compromise the stability of the electrical system. A significant precedent was the solar storm of March 1989, which caused a widespread blackout in Quebec (Canada), affecting 6 million people in less than 90 seconds. If a phenomenon of that magnitude were to occur in Spain, the impact could extend to the entire national electrical system for hours or even days.