Environmental impact of electricity from selected geothermal power plants in Italy

Geothermal plants supply a significant contribution to the electricity balance from renewable sources in Tuscany. However, this electricity conversion is not exempt from environmental drawbacks. In our study, the electricity production phases of four geothermal electricity plants are analyzed by means of a careful airborne emissions assessment carried out over the entire LCA of the plants. The impact categories considered are global warming (GWP), acidification (ACP) and human toxicology (HTP). The functional unit used is 1 MWh of electric energy produced from geothermal power plants in Mount Amiata area. For the environmental impact categories considered, the impact potentials are evaluated for each of the four geothermal power plants as follows: 380-1045 kg CO2 eq/MWh for GWP, 0.1-44.8 kg SO2 eq/ MWh for ACP and 1.1-31.6 kg, 1.4-DB eq/MWh for HTP. The main contributions to the impact are associated with the high content of NH3, H2S, CH4 and CO2 gases present in the effluents of each plant. The impact change in relation to the geothermal site has a strong correlation to the basin of fluid withdrawal and is related to the technologies used for pollutants depletion. In some cases the impact is higher than that found for production of electricity from fossil fuels (for example, a coal plant of comparable power). (C) 2013 Elsevier Ltd. All rights reserved.