The fuel and energy complex of Russia is going through a crisis state. The main problem is the interruptions of the power supply of remote areas. One of the most promising solutions in this situation is the development of the small power for the decentralized energy supply. A cogeneration or combined heat and power systems have a great potential in the solution of this issue. In this paper, an analysis of different energy sources of cogeneration, the prime movers, is made from the point of view of the advantages and disadvantages, both technical and operational and environmental. Depending on the existing requirements, as the primary engine could be used: the reciprocating engine (or piston engine), the steam turbine, the gas turbine, fuel cell systems and the Stirling engine. In the paper there are reviewed principle of operation, size range, electrical, thermal and total efficiencies and fuels that are used for each of these cogeneration technologies.