The increasing share of renewable electricity will make energy storage technologies indispensable in the future. In this study, the potential of grid energy storage technologies is discussed, focusing on the Nordic countries as well as Germany. It is challenging to balance the intermittency of wind power and solar power production in the energy system. In Norway and Sweden, and to some extent Finland, hydropower is a very important balancing resource. Compressed Air Energy Storage (CAES) is a technology that has not had a real breakthrough yet. There are ongoing projects at different locations where one of the targets is to achieve better round-trip efficiency by taking care of the heat generated at compression. Pumped hydroelectric storage (PHS) has advantages in being cost-efficient and has a high round-trip efficiency. There is probably a high theoretical potential of new generating capacity in Norway and Sweden, but the electricity cost does not vary enough for new developments to be profitable at the moment. The environmental and social impact of PHS plants is an important and difficult aspect to handle. Power-to-gas, power-to-power and hydrogen storage has been getting more attention recently but needs more research to increase the round-trip efficiency and to reduce the costs of electrolysers, storage and fuel cells. Batteries can be well suited as a minute reserve or for peak shaving but are currently not cost-efficient for long-time storage. With lower prices and the possibility of using more abundant metals with less environmental and social impact batteries could play a larger role in electric grids. There might be possibilities of integrating batteries in electric vehicles with power systems as well.To speed up the development of energy storage technologies, governmental subsidies might be necessary. In the future, a larger variation in electricity cost can be expected during different times of the day and the year, which will make energy storage facilities more profitable.