The invention relates to an arrangement of a gas decompression turbine (1) in a gas supply line system. The invention provides for an asynchronous motor (3) or asynchronous generator to be positioned in a section (2) of a gas supply line on the incoming (high-pressure) side of a radially arranged separating wall (5) fitted with nozzles (4) for decompressing the gas. At least one bucket wheel (7) of light-weight construction and driven by the gas current is mounted on the shaft (6) on the outflow (low-pressure) side behind the nozzles (4). The invention provides for devices for absorbing the electrical energy generated by the generator of the asynchronous motor (3) and for feeding said energy into an energy supply network. It further provides for a control device (9) which sends a control signal to a safety valve (10) positioned on the incoming side in front of the asynchronous motor/generator for (partially) closing the section of gas supply line when the shaft (6) exceeds a critical number of rpms.