Blackout Spain, 22 years ago the tree that plunged Italy into darkness: here's what happened

Italy too, like Spain, experienced a maxi blackout that paralysed the country: it happened on 28 September 2003, when around 3.27 a.m. it found itself almost entirely without electricity.

The interruption lasted no more than 12 hours and was due to the fall of a tree in central Switzerland, in Canton Ticino, on a high-voltage line supplying Italy. This fall caused the remaining lines to be overloaded, which in turn shut down. It was only discovered later that the Swiss transmission system operator Etrans (today Swissgrid) delayed repair work and did not promptly inform the Italian transmission system operator GRTN (today Terna) of what had happened.

The phenomenon caused major disruptions: the interruption of transport services (including airports and stations), the switching off of traffic lights and the blocking of lifts. Road traffic was also aggravated by the rain. The blackout hit Italy while the first edition of the Notte Bianca was taking place in Rome, in which some 500,000 people were participating, many of whom were stranded in the streets and subways.

The situation returned in the course of the day, with the supply of electricity restored first in the North and then in the South. In the North, electricity was restored around 9.00 am, in the Centre at 4.30 pm (in Rome from around 11.30 am), in the South at 7.00 pm, while Sicily had to wait until 10.00 pm. The only areas that were not affected by the blackout were the islands of Pantelleria, Capri, the Egadi Islands, and Sardinia.

The blackout was caused by a number of interconnected factors. The main problem was the vulnerability of the Italian power grid, which was heavily dependent on imported energy from abroad. The tree fall on Swiss territory and the consequent failure of the power lines were only the first link in a chain of events. The episode marked a turning point for the Italian energy system and rang alarm bells, leading in the years to come to the launch of a plan to modernise the infrastructure itself and at the same time increase energy production from renewable sources, such as wind and solar power.