TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Method: The dynamic gas separation step is a step for pneumatic gas separation (5) via pressure-adsorption or an upstream- or a downstream membrane method. The dynamic gas separation step and/or the pneumatic gas separation step comprise several successively connected partial steps. A separation of impurities including dirt particles and/or gases with higher molecular weight than methane takes place before and/or in the dynamic gas separation step. The low-methane weak gaseous phase obtained in the gas-separation step is burnt with an oxidizing agent in an energy generating device to produce energy, and the generated energy is provided at least partially to carry out the dynamic gas separation step. Preferred Components: A gas centrifuge or a vortex tube is provided in the step of dynamic gas separation, or to the device for the dynamic gas separation. The device for the gas separation is formed with two steps, where the first step comprises the device for dynamic gas separation, and the second stage comprises a device for pneumatic gas separation including a pressure swing adsorption system or a membrane system. The device for dynamic gas separation and/or the device for pneumatic gas separation comprise several separators connected in a row. The device for dynamic gas separation and/or the device for pneumatic gas separation comprise the energy generating device, which supplies the electrical or mechanical energy to the device for dynamic gas separation and/or the device for pneumatic gas separation, where the energy generating device is equipped with a combustion chamber for burning a fuel gas with the oxidizing agent, and is fluidically connected with a oxidizing agent supplying pipe and a delivery pipe for weak gas generated in the device for dynamic gas separation and/or in the device for pneumatic gas separation. The energy generating device comprises a generator with a rotatable rotor mounted on a shaft, which is operatively connected with a driving shaft of the gas centrifuge for transmitting the rotational movement.