|Lisbon and London
Shortly after noon on Monday April 28th, Spain’s electricity grid suddenly and unexpectedly lost 15 gigawatts of power—equivalent to 60% of its national demand. The massive drop caused most of the country’s electricity system to shut down, followed by much of neighbouring Portugal’s. Trains and metros ground to a halt and 35,000 passengers across Spain had to be evacuated. Traffic lights stopped working; hospitals cancelled all non-essential operations; mobile-phone networks and the internet went dark.
The chaos lasted for hours. Though Portugal recovered by the end of the day, most of Spain’s electricity was not restored until 7am the next day. Red Eléctrica de España (REE), Spain’s state-controlled national electricity operator, called the blackout “exceptional and totally extraordinary”. Pedro Sánchez, Spain’s prime minister, promised to “get to the bottom” of what happened.
For now, authorities are in the dark. Rumours of a cyber-attack have been dismissed by REE; AEMET, Spain’s meteorological agency, has said that it has not detected any “unusual meteorological or atmospheric phenomena”, or sudden temperature fluctuations that could be a possible culprit. Identifying the true cause may take weeks, says Mike Hemsley of the Energy Transitions Commission, a London-based think-tank.
That has not stopped some from questioning the resilience of energy systems mostly powered by renewable sources. Spain and Portugal have some of the highest shares of wind, solar and hydro power in Europe: in 2024 these provided nearly 60% of Spain’s electricity, and over 70% of Portugal’s. The comparable figures for Britain, France and Germany are closer to 40%, 30% and 50%, respectively. Are renewable-heavy grids especially failure-prone?
Not necessarily. Even though the initial failure seems to have occurred in south-west Spain, the source of most of the country’s solar power, at a time of day when the grid would have been basking in solar, two other faults then followed hard on its heels, including one in the connection between Spain and France. Simultaneous failures of this kind could be enough to take out any grid, says Janusz Bialek, an electrical engineer at Imperial College London, as their probability is low enough to make protection prohibitively expensive. That means even fossil-fuel-heavy grids can grind to a halt, as seen in Italy in 2003. Natural-gas plants ill-prepared to handle the harsh winter may also have contributed to Texas’s dramatic blackout in February 2021.