Hydro Power & Storage In Europe

Developed and untapped hydropower potential
[endseurope.com]
Europe:
Installed hydro storage capacity: 180 TWh. [source]
Electricity consumption: 3,636 TWh/yr. [source]
Hydro storage reserves in days: 18 days
[ec.europa.eu] – Assessment of the European potential for pumped hydropower energy storage
this study which focuses on two topologies:
(T1) when two reservoirs exist already with the adequate difference in elevation and which are close enough so that they can be linked by a new penstock and electrical equipment
(T2) based on one existing reservoir, when there is a suitable site close enough as to build a second reservoir.
The results show that the theoretical potential in Europe is significant under both topologies, and that the potential of topology 2 is roughly double that of topology 1. Under T1 the theoretical potential energy stored reaches 54 TWh when a maximum of 20 km between existing reservoirs is considered; of this potential approximately 11 TWh correspond to the EU and 37 TWh to candidate countries, mostly Turkey. When a shorter maximum distance between existing reservoirs is considered, e.g. 5 km, the majority of the 0.83 TWh European theoretical potential is in the EU (85%).
Under T2 the European theoretical potential reaches 123 TWh when the distance between the existing reservoir and the prospective site is up to 20 km. Unlike topology 1, in topology 2 the majority of this potential (50%) lies within the EU. For a distance between reservoirs of 5 km a theoretical potential of 15 TWh -of which 7.4 TWh within the EU- was found.
P.S. the figures mentioned need to be reconciled: 180 TWh and the other ones.
[source]