Industrial districts are highly characteristic of Italian industry structure, with energy implication due to both electrical and thermal energy demand. The present study represents an environmental methodology approach applied to an area in the Tuscany region characterized by the presence of a high net power output cogeneration plant connected to paper mill processes. The cogeneration unit is based on a innovative gas turbine characterized by low atmospheric environmental impact. Additional impact due to cogeneration plant installation was evaluated in comparison with pollutant concentration levels due to existent energy conversion processes, using atmospheric diffusional models. A comparison was also made with respect to pollutant concentration contribute due to ordinary road and highway traffic emissions existent in the area.