Risk register · entry
Q3 · EngineeredIberian Peninsula blackout
Cascading generator trips blacked out Spain and Portugal for hours.
Tightly coupled systems where one small fault cascades and takes down the whole machine.
Why this quadrant
Grids run inside a voltage and frequency band, and outside it protection equipment disconnects to save itself. That is the correct behaviour for one generator. When a 582 MW trip near Badajoz set the next plant doing the same thing 360 milliseconds later, every unit protecting itself removed the thing the others needed. Spain and Portugal lost 31 GW.
The record
- 31 GW total load lost (25.2 GW Spain, 5.9 GW Portugal)certain
- Blackout onset 12:33 CEST, 28 April 2025certain
- 582 MW generation trip at Badajoz-area substation at 12:33:16.460, followed 360 ms later by a second PV plant disconnectioncertain
- Restoration: Portugal by 00:22 CEST, Spain by approx. 04:00 CEST on 29 April (approx. 10 hours)certain
- At least 8 deaths (7 in Spain, 1 in Portugal)likely
- Approximately 35,000 train/metro passengers required rescue in Spainlikely
- Estimated business losses of about €1.6 billion (CEOE estimate, not an official government figure)uncertain
- ENTSO-E Expert Panel final report released 20 March 2026, panel of 49 memberscertain
- Red Eléctrica's own incident report submitted 18 June 2025certain
Sources
The newsletter
One risk story a week, taken apart the way this one was: what was known, what was ignored, and which quadrant it really belonged to.
No spam, one email a week.