Targets established by the European Union for 2020 have introduced huge attention toward electrical energy management, starting from its sustainable production and researching and developing new production technologies based on renewable power sources, to its correct use and storage. However, storing renewable energy is still the main challenge to guarantee the use of this energy. The main energy storage techniques can be classified as: 1) Magnetic systems: Superconducting magnetic energy storage; 2) Electrochemical systems: Batteries, fuel cells, super-capacitors; 3) Hydro systems: Water pumps; 4) Pneumatic systems: Air compressors; 5) Mechanical systems: Flywheels; and 6) Thermal systems: Molten salt, water or oil heaters. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved..