This is how Spain recovered from the great blackout: an energy-related oil slick that spread across the peninsula.

The electricity system's demand has been restored to 99%. Although the data is from 6:00 a.m., Red Eléctrica announced it on its X account at 6:46 a.m. and at 6:49 a.m. it was confirmed - in her case, on Bluesky - by the Third Vice President of the Government and Minister for the Ecological Transition: 100% of the 680 substations in the transmission network are in service, restored. It is not yet known what caused the blackout, but it is known how we recover from it.

In reality, it's worth noting that the response has been relatively swift, and everything was put in place practically from the moment the power failure occurred, detected at 12:32 p.m. on Monday. Communication protocols were also initiated between the manager, industry companies, the government, and authorities. But from the electrical perspective, everything began in France, Morocco, and hydroelectric plants prepared for this eventuality.

Neighboring countries used their border connections to spread power to Catalonia, the Basque Country, and Andalusia. This allowed their systems, which had also been down, to be brought online and, from there, to spread power to the rest of the peninsular electrical system. The power, so to speak, spread like an oil slick across the country.

At the same time, a group of hydroelectric plants capable of autonomous startup came online when the blackout was detected and proceeded to connect to the grid. Broadly speaking, their role was the same as that of Morocco and France: to establish these zones and gradually expand them as they reached new supply points. The voltage spread throughout the grid, and these energy islands grew until it was possible to interconnect them all. In its 9:00 p.m. announcement, Red Eléctrica reported that at that time there were no islands left.

In this process, different sources were connected to the system. The two key ones were the aforementioned hydroelectric plants and combined-cycle plants, which burn fuel—usually gas—and can be started up relatively quickly. If they are already operating, which wasn't the case, it's almost immediate. Nuclear power also takes several hours—about 12—to resume generating electricity, but once it does, it will provide continuous generation. In the midst of the power outage, the operators of Spain's nuclear power plants notified the Nuclear Safety Council of the declaration of a pre-alert emergency situation due to the loss of external electricity supply. It was a safety shutdown. As the sun rises, solar photovoltaic power will resume.

This "oil slick" didn't need to reach the islands and Ceuta and Melilla, because they have autonomous systems and weren't affected by the outage. This, however, doesn't make them more robust, and in fact, it's much more common for an island to go down when a zero like the one on the peninsula occurs. In the Canary Islands, the entire system doesn't go down because they operate precisely as energy islands, except for Lanzarote and Fuerteventura, which are connected by a submarine cable.

New fall?

The big question now is whether the system could fail again. The reality, again, is that this normally doesn't happen, because it's very robust and has redundant sources capable of backing up each other and safeguards (electro-intensive industries, for example, can be disconnected). But the reality is also that it failed yesterday. Until we know for sure what happened, nothing can be guaranteed. However, if this return to normal is, in fact, a return to normal, it should hold now that all the substations are back online.