I thought Sweden had plenty of hydro for balancing, too.

En un viejo país ineficiente, algo así como España entre dos guerras civiles, poseer una casa y poca hacienda y memoria ninguna. -- Gil de Biedma

Furthermore, the balancing capacity in Sweden is in the north (where the rivers are) while the demand is in the south (where people live). North-south transmission capacity is limited, so you can get issues both with wind located both in the north (lines are full of power and dams are full of water, no room left for wind) and in the south (lines are already full of power and suddenly the wind dies down in the south...).

Peak oil is not an energy crisis. It is a liquid fuel crisis.