The aim of the work is the analysis of energetic and economic advantage of installing an air cooling system at the inlet of a gas turbine set (compressor - combustor - turbine), in a 5 MW CHP plant. Two different solutions have been compared: the first one is an absorbption chiller fed by heat recovery from the gas turbine, through an heat exchanger; the second one is a traditional cooling system by CFC compression cycle, electrically fed by electrical generator coupled with gas turbine.