NOVELTY - The integrated process for storing and restoring an electrical energy, is claimed, where: the process of storing the electrical energy is carried out by water electrolysis step, methanation step and reacting hydrogen obtained from electrolysis with carbon dioxide; and the process of restoring the electrical energy is carried out using a heat engine coupled to an electrical generator. The heat engine is operated by: combustible methane that is obtained from methanation step and oxycombustion step; and combustion oxygen that is produced by electrolysis.    USE - The integrated process is useful for storing and restoring an electrical energy including wind energy, solar energy, hydroelectric energy over water, energy of sea waves, tidal energy, geothermal energy and hydroelectric energy of barrier.    ADVANTAGE - The integrated process is capable of simply and economically storing and restoring the electrical energy without environmental pollution.    DETAILED DESCRIPTION - The integrated process for storing and restoring an electrical energy, is claimed, where: the process of storing the electrical energy is carried out by water electrolysis step, methanation step and reacting hydrogen obtained from electrolysis with carbon dioxide; and the process of restoring the electrical energy is carried out using a heat engine coupled to an electrical generator. The heat engine is operated by: combustible methane that is obtained from methanation step and oxycombustion step; and combustion oxygen that is produced by electrolysis and is optionally diluted in carbon dioxide or water vapor. Water, which is supplied to the electrolysis or used to dilute the oxygen, results from the condensation of the gases obtained from the methanation step or the exhaust gas in the heat engine. The carbon dioxide, which is supplied to the methanation or used to dilute oxygen, results from the exhaust gas in the heat engine. The net flow of water and carbon dioxide consumed by the electrolysis and methanation steps are equal to net flows of water and carbon dixoide produced by the oxycombustion step. The net flow of methane and oxygen consumed by the oxycombustion is equal to net flows produced by electrolysis and methanation steps so that the process operates in a closed circuit without external input or loss of material. The electrolysis is carried out by low pressure alkali electrolyzer and a proton exchange membrane electrolyzer or using high temperature distilled water. The methanation step is carried out at a pressure of 1-30 bars and at a temperature of 300-400 degrees C, and is carried out using a nickel or ruthenium catalyst on alumina substrate. An INDEPENDENT CLAIM is included for an integrated system for storing and restoring an electrical energy.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic block diagram of an integrated system.    Water reservoir (2)    Carbon dioxide reservoir (3)    Electrolyzer (4)    Oxygen reservoir (5)    Methanation device. (7)