Growth of wind and solar power. Which storage for electric power?

As the part of wind and solar power is steadily growing in France (while staying at a rather low level), and as these power sources are intermittent, a solution may be found in the development of energy storage systems. However, due to the intermittency of wind and solar power, energy storage must be adapted to the daily and weekly power variations (these variations are detailed for the case of wind power). This paper discusses the development of such energy storage systems: electric batteries (notably lithium based batteries), pumped storage, power-to-gas-to-power, and load management. Power storage costs are evaluated