Local conditions
While the grids in Spain and Portugal are connected to each other, they have limited connections to elsewhere. The only sources of external power to the grid come from France and Morocco, which are small connections, but they could be used to help black start some plants. Both blacked-out countries have significant hydropower, with Spain seeing it cover 10 percent of its demand and Portugal 25 percent. That’s useful because hydro plants need very little in the way of an external power supply to start operating.
Beyond that, both countries have invested heavily in renewables, with Portugal supplying about half of its power from wind and hydro,
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