The aim of the intended developed system is in direct use of low-potential and high-potential heat generated in internal combustion engine by means of a partially verified ORC technology. Goal is to achieve a reduction in the uni investment of such a system, due to the possibility of absence water and oil cooling circuits and intermediate circuit for heat recovery from flue gas. The total waste heat transferred from ICE to the optimally selected working substance ORC is then utilized utilized by an expander, which assumes a total increase in the usability of the primary energy source and hence the reduction of emissions per unit of electricity produced. This will provide a relatively simple, affordable and high-efficiency cogeneration unit for natural gas.