Spain and Portugal blackout highlights vulnerability of Europe's energy grid
Passengers wait outside Atocha train station during a nationwide power outage in Madrid, Monday, April 28, 2025. (AP Photo/Manu Fernandez)
What we know at this point is that there was a massive power outage affecting the entire Iberian Peninsula at 12.30pm local time in Spain.
This was a complete “blackout” in that the entire national electricity grids of Spain and Portugal shut down.
This is the largest electricity blackout in Europe in recent memory, and possibly one of the largest ever in terms of its scale and its disruption to everyday life for tens of millions of people.
Spain and Portugal not only lost electrical power but also lost many other essential services. Internet and telecommunications were severely impacted, as well as transport, with rail and metro services and airports all closed.
There was chaos on the roads, with traffic lights out of service across all the major cities. Banking and card payment services were also impacted.
The root cause of this blackout is still unknown. Spanish authorities have not explained the cause of the event — as of Monday night — and are asking the public not to engage in speculation for now.
It appears that there is no suspicion of cyberattacks or other foul play, and the very sudden, widespread blackout seems more in line with a technical failure of the transmission grid.
One theory — which is being given some attention, as the Portuguese grid operator suggested it — is that this event was caused by a very “rare atmospheric phenomenon,” with extreme temperature variations across Spain resulting in oscillations on high-voltage power lines.
The theory is that these oscillations were severe enough to cause the Spanish and Portuguese grids to lose synchronisation, or disconnect from, the rest of Europe.
However, we do not yet have any official explanation of the root cause, and it may take some time for this to be established.
When the national electricity grid is shut down completely, power needs to be restored using a process called a “black start.”
The dead electricity grid is gradually brought back into service, one generating station at a time, and region by region, until it is eventually restored to full service.
This process is being carried out on Monday afternoon and evening, and it is expected that most electricity users across Spain and Portugal will be reconnected by Tuesday.
Large-scale blackouts like this are extremely rare, but they can happen. The electricity grid is a vast and complex system. It is sometimes called the “largest machine ever built by mankind.”
Millions of individual grid components need to work together in order to have a safe, reliable electricity supply. Failures and malfunctions of these components happen all the time.
Usually, there is enough redundancy in the system to ride through these issues without large-scale disruptions.
It is difficult to assess the level of risk to other electricity grids, such as Ireland’s, without yet knowing the root cause of the Spain and Portugal blackout.
Grid operators across the world want to know how and why this event happened, and if there are similar vulnerabilities in other grids.
There will undoubtedly be learnings from this blackout, but the full investigation needs to be carried out first, and this will take time.
Grid operators need to go through reams of measurement data from electrical installations across the grid, and physically inspect affected high-voltage equipment, then piece it all together.
Regardless of the outcome of this investigation, this blackout—and other events such as the recent Heathrow Airport power outage and Storm Éowyn in Ireland—are now putting a spotlight on critical infrastructures such as the electricity grid.
It highlights the need to update and modernise our energy infrastructure in order to ensure energy resilience into the future.
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