Why Restarting a Power Grid After Massive Collapse Is So Hard

It’s a worst case scenario that grid operators plan for but hope never to encounter. After one of the worst blackouts in Europe in more than a decade, electricity grid operators in Spain and Portugal are trying to get networks back up and running from the ground up.

The initial estimate from grid operator Red Electrica was that restoring all power supply in Spain may take between six and 10 hours. By Monday evening, that was looking optimistic — at 9pm Madrid time, there was 17.3 gigawatts of demand on the grid, about two thirds the amount seen just before ...