This paper analyses the flexibility provision for future electricity systems by bulk energy storage technologies (EST) as well as transmission capacity expansion based on selected European case studies. For this, future potentials of bulk EST in different European countries were estimated and matched with the spatial dispersion of future wind-deployment on country-level to be able to estimate the possible direct benefits of bulk EST implementation to balance the incumbent electricity system. Further on, the contribution of possible future transmission grid expansion for bringing together centers of variable wind generation and flexible generation was analyzed. In this context, an example of transmission expansion is presented: Central Western Europe and Nord Pool, where a cost / benefit analysis of transmission investments based on a welfare maximization approach is conducted. However, both technology options are needed to perfectly operate future European electricity systems with high shares of variable renewable electricity generation.