NOVELTY - The power supply system comprises an electric current generating means for regeneratively producing electric energy storable in a power supply network (2), a device (3) for generating hydrogen under use of electric energy of the regenerative electric current generating means, a methanisation device (4) for the transformation of hydrogen produced through the hydrogen generating device and a carbon dioxide gas to be supplied in a methane-containing gas stored in a gas supply network (7), and a converting device for producing electric energy under use of gas from the gas supply network.    USE - Used as power supply system.    ADVANTAGE - The power supply system ensures stable and reliable power supply with a high proportion of current renewable energy sources.    DETAILED DESCRIPTION - The power supply system comprises an electric current generating means for regeneratively producing electric energy storable in a power supply network (2), a device (3) for generating hydrogen under use of electric energy of the regenerative electric current generating means, a methanisation device (4) for the transformation of hydrogen produced through the hydrogen generating device and a carbon dioxide gas to be supplied in a methane-containing gas stored in a gas supply network (7), a converting device for producing electric energy under use of gas from the gas supply network, means for supplying carbon dioxide to the methanisation device from a power station delivering carbon dioxide, means for supplying carbon dioxide-containing gas to the methanisation device from a biogas plant, means for heat transmission from the methanisation device to biogas plant, means for the supply of natural gas substitute obtained from the biogas plant to the gas supply network, means for the supply of carbon dioxide-containing synthesis gas from a biomass-gasification plant to the methanisation device, organic Rankine cycle plant for producing electric energy under use of waste heat of methanisation device, a petrol station device for providing vehicle with hydrogen produced from the hydrogen production device and/or with electric energy produced from the regenerative current generating means and/or with natural gas substitute produced from the methanisation device, a current network on which the current generating means, the hydrogen generating device and the converting device are coupled, a gas supply network on which the methanisation device and the converting device are coupled, a gas storage that is coupled on the gas supply network, and a control device. The electric current generating means comprises wind power stations, photovoltaic systems, geothermal power plants, biomass power plants, hydroelectric power plants and/or solar thermal power plants. A gas storage device for storing hydrogen, additional gas and/or displacement gas in the gas supply network under use of methane-containing gas from the methanisation device and/or the hydrogen from the hydrogen generating device. The control device adjusts a reduced or increased input power of the hydrogen producing device in periods with increased and/or decreased production power requirement of the power supply network and/or an increased or decreased feed-in-power of the converting device, in dependent upon a time-dependent power requirement of the current network or in dependent upon a predicted power requirement profile of the power supply network and/or a predicted current generation profile of the regenerative current generation means. An INDEPENDENT CLAIM is included for a method for operating a power supply system.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic block diagram of a power supply system (Drawing includes non-English language text).    Power supply network (2)    Device for generating hydrogen (3)    Methanisation device (4)    Carbon dioxide source (6)    Gas supply network. (7)