What does 'black start' capability refer to?

'Black start' capability refers to the ability of a power station to start generating electricity without the need for external power sources. This capability is essential for restoring a power grid after a blackout. In the event that the electrical grid experiences a complete failure, a black start allows certain power plants—typically those equipped with hydropower, gas turbines, or diesel generators—to start up independently and begin supplying power. Once these plants are operating, they can provide electricity to reinstate the grid incrementally and eventually bring other plants back online, facilitating a full recovery of the electrical system. This operation is crucial because, during a blackout, the grid is entirely down, and conventional power plants cannot start unless they receive power from the grid itself. Therefore, having facilities with black start capability is vital for the resilience and reliability of the electrical grid.