The paper discusses fuel efficiency of the CHP plant with increased flexibility in self-feeding mode. Self-feeding mode refers to the treatment of water in the boiler of the plant by burning fuel and by electricity generated by the plant itself. A certain share of electricity from the generator output, which the RES sources have made redundant in the power system, is used in the boiler of the plant to obtain steam with the required parameters, thus reducing the power sent to the system and reducing fuel consumption while maintaining the operating temperature regime of the plant equipment. Both fuel and electric heaters have significantly lower thermal inertia than other plant components and can be cheaper to replace if necessary. The effect of such self-feeding is an increase in flexibility. It becomes obvious when it is necessary to decrease the generation. The rapid increase in electricity generation can be provided by hydropower plants or in other way and by CHP in question if it previously worked in self-feeding mode. The fuel efficiency decreases when more electricity from output of the power station is sent to the boiler.