How long is internet available during a blackout?

The internet can survive a few hours without power, but not for long. Large data centers are protected by their own clusters that can operate indefinitely. But the network relies on intermediate clusters that have a much shorter lifespan, which could be seriously compromised by a massive blackout like the one currently being experienced on the Iberian Peninsula.

“The internet works because there is intermediate equipment [data switches] distributed throughout cities; much less is needed because fiber optics travel very quickly and very far,” says Arturo Azcorra, deputy director of Imdea Networks, a technology research center.

Even if large data centers survive, without this intermediate equipment, the connection would not be possible: “It’s as if the central nervous system worked, but the peripheral system did not,” says Azcorra.

Vodafone, for example, has reported that its network is currently 70% active, thanks to backup generators, but its operation will depend on how long the blackout lasts. “At Vodafone Spain, we recommend that our customers with cell phone communications use their services responsibly to avoid overloading the service,” the company states. Other telephone companies have not yet provided updates on the status of their networks.

Therefore, while service is restored, the connection depends primarily on Wi-Fi access, which requires electricity that office buildings, for example, can produce autonomously.

On the street, base stations —rooftop antennas— don’t work unless they’re near critical locations and have special equipment to generate electricity, as can also be the case in rural areas. For this reason, cell phones without Wi-Fi access are unlikely to work. “If someone walking past a critical location, such as a security forces headquarters, they might be able to connect, but typically they won’t be able to connect or make calls,” explains Azcorra.