The share of renewable energies on the net electricity consumption is rising rapidly all over the world and governmental goals of a full renewable electricity supply by 2050 are getting more and more common. Especially intermittent, non-controllable energy sources like wind and sun will play a significant role to reach these targets. The fluctuating nature of these two energy carriers will pose some mature problems to energy supply systems. Solving these problems will be one of the mayor challenges in the next decades. With an installed amount of non-controllable power that exceeds the yearly peak load, situations will occur with a surplus of energy that can be rejected, exported or stored. This paper deals with an empirical approach to estimate the future energy storage needs from an electricity system point of view. The energy storage needs will further be divided into short and long term energy storage.