Note on the Iberian blackout — causes, consequences and public power

On 28–29 April 2025 the electricity supply failed across Spain, Portugal and parts of southern France. About six crore people were without power for more than twelve hours. Metros stopped in Madrid, Barcelona and Lisbon. Madrid-Barajas delayed 220 flights.

At the hour of the failure, wind and solar supplied about 80 percent of electricity in Spain and Portugal. A sudden 1.2 GW drop in solar output moved the frequency. Ageing 400 kV lines, some more than thirty years old, oscillated and the failure cascaded. Private operators had put new renewable plant ahead of the grid that has to carry it.

European grids are coupled without proper public control of the utilities. Frequency movement in Spain passed into the neighbouring countries. The same questions stand over monetisation of Indian grids, heavy dependence on variable renewables, and the One Sun One World One Grid coupling project.

The note is for discussion among workers of POWERGRID and NTPC. Integrated public governance of generation, transmission and distribution — not fragmentation for the market — is the line the Centre places before the unions.