This work analyzed the environmental compatibility of a biomass plant to be constructed to produce both electricity and heat (bioenergy) in a small town in Piedmont (northern Italy). In order to study both the critical local impacts (with specific reference to air quality) and the overall environmental benefit (decrease of GHG generation), we evaluated the emissive flow modifications for the hypothesis of activating the biomass plant in the municipal area, by considering introduced and eliminated pollutant loads. This analysis included a consideration of the non-energy-related emissions (“ground value”) currently operating in the area. After carefully analyzing the major operational characteristics of the proposed plant and the principal characteristics of the surrounding territory and its energy needs, the evaluation was conducted using the tools of mass and energy balances, and an external costs methodology was also applied in order to define the social cost of the plant. In addition, the plant′s potential modification to local air quality was evaluated by considering the meteorological and physical characteristics of the considered area, using a pollutant dispersion model. Several different configurations for the flue gas purification line were also considered, so that the evaluation of the costs and benefits was based on the analysis of both industrial and external costs. The conclusions, while based only on the specific studied case, can be considered to be fairly representative in general as a methodological approach for studying the effects of the implementation of biomass energy plants.