Assessment of Geothermal Power Plants Impact on Air Quality – Effect of H2S Abatement with AMIS in the Larderello-Travale-Radicondoli Geothermal Area (Tuscany).

Abstract

This study is a regional assessment of the results achieved by the installation of AMIS® abatement systems on geothermal power plants in reducing the potential impact associated with emissions of hydrogen sulfide (H2S) and mercury (Hg) in the Larderello-Travale-Radicondoli Geothermal Area (Tuscany). The AMIS® abatement system has “rated values” of efficiency up to 90% for H2S and 95% for Hg. Starting from the year 2002, AMIS® abatement systems have been installed on new and existing geothermal power plants progressively in the frame of a program still in progress. This study evaluated the effects of the AMIS® spread in the geothermal concession comparing the scenario for the year 2003 (27 power plants, 1 with AMIS® for a total installed capacity of about 720 MW) with the 2007 scenario (27 power plants, 10 with AMIS® for a total installed capacity of about 720 MW). The study was conducted both analyzing the air quality measured and by applying the CALMETCALPUFF modelling system. The results show that in the 2007 scenario the reduction of the GPPs contribution to the annual average concentration of H2S is greater than 25% in 90% of the domain and greater than 40% in about 10% of the domain. The reduction in the number of odour threshold exceedances induced by the power plants (not considering the natural background concentration) is greater than 10% in the 90% of the domain and greater than 50% in about 10% of the domain.