The creation of energy-saving turbogenerators is an essential component of the development of small energy systems. The gradual growth of interest in distributed electricity generation necessitates the constant improvement of these units. Moreover, they implement a more environmentally friendly generation method than when using microturbine units that use fuel to carry out the work process. Nowadays, turbogenerators are created based on different types of expansion machines, which have their advantages and disadvantages, given in this article. Compared to competitors, vortex expansion machines have good prospects and the necessary potential to expand their research and produce turbogenerators. An experimental vortex expansion machine with a peripheral-lateral channel and ability to change the geometric parameters of its flowing part was created to meet these needs. Experimental studies of the machine were performed on a special stand with air as a working fluid. As a result of the tests, the data were successfully obtained and processed. They are presented in the form of tables and graphical dependencies. The nature of the influence of thermodynamic parameters and geometric parameters of the flow part on the efficiency of the vortex expansion machine and turbogenerator based on it to further improve and create new turbogenerators is clarified.