The share of renewable energy in energy consumption has been growing strongly over the last 10 years in Europe and should only increase, driven by a context and objectives very favourable to the development of the sector. This is a real step towards decarbonised energy, but the intermittence of wind and solar production systems with an average charge rate of 24 % and 15 % respectively (RTE, 2015) versus 75 % for a nuclear power plant poses some problems: — Disbalance of the electricity grid between electricity supply and demand; Increased frequency disturbances, with recurring problems of local congestion and risk of blackout. Energy storage, a flexible tool, presents itself as a logical alternative to the costly development of the electricity grid and overcapacity for renewable electricity generation and source stations. It makes it possible to arbitrate between periods of renewable energy production and consumption periods involved in the integration of renewable energies, the stabilisation of the electricity grid and reducing investments to strengthen the grid. Power-to-Gas (P2G) is a storage solution based on the water electrolysis process that allows renewable water and electricity to generate green hydrogen and a methanation process that combines this hydrogen with carbon dioxide to produce synthetic methane, similar to the natural gas.