The aim of the work is to develop an energy-saving device that provides the conversion of thermal energy into electrical energy. The design and materials of the thermoelectric converter unit, consisting of 12 thermoelectric converter modules, a cooling radiator and a switching unit, were developed and selected. Based on the test results, the zone of the maximum temperatures in the section of the gas duct recommended for the installation of a gas cooling module using a thermoelectric converter was determined. The technology for cooling gases with the help of a thermoelectric converter was tested on the site located in front of the experimental heat exchanger. An assessment of the efficiency of the conversion of heat into electrical energy was conducted using the design of the thermoelectric converter unit, based on thermoelectric modules TGM 127-1.4-1.2. It was determined that the device is capable of generating electricity stably for production needs. The data obtained showed that, at a temperature difference of 75–80 °C between the wall surface of the gas duct section and the coolant, the power of one thermoelectric converter block of the gas cooling system reaches 9 W.