The environmental impact of electric power production through an Integrated Gasification Combined Cycle (IGCC) fired by dedicated energy crops (poplar Short Rotation Forestry (SRF)) is analysed by a Life Cycle Assessment approach, The results are compared with the alternative option of producing power by conventional fossil fueled power plants, The energy and raw materials consumption and polluting emissions data both come from experimental cases. Thermodynamic models are applied for simulation of the energy conversion system. The results establish relative proportions for both consumption and emissions of the two energy systems, in detail. Considerable differences emerge about the environmental impact caused by the different gasification conditions. The evaluation of the environmental effects of residues of the pesticides in ground/surface water and in the soil required a particular care, as well as the characterisation of all chemicals (herbicides, fungicides and insecticides) used for the crops.