| Abstract |
Volcanic and non-volcanic geothermal areas often exhibit surface emissions of gases and steam, both hot and cold. This study aimed to assess the relative contribution of CO₂ emissions from geothermal power plants compared to natural ground emissions. Diffuse soil emissions were measured using accumulation chambers, while localized emissions were analyzed with volumetric systems and gas composition analysis. In Larderello, over accumulation chamber method also a historical reconstruction was used, analyzing emissions from the ancient “lagoni” once exploited for boric acid. Historical production data and gas analyses revealed that natural emissions have nearly vanished due to deep drilling and steam extraction for electricity generation—quantifying the depletion of natural emissions. In Monte Amiata, widespread and focused soil emissions were measured, revealing high CO₂ fluxes even in areas without geothermal plants (e.g., Bagni San Filippo). However, total emissions in developed areas were significantly lower than in undisturbed zones. The study quantitatively compared emissions from developed and natural areas, showing that the reduction in natural emissions is of the same order of magnitude as emissions from geothermal plants. This is clearly demonstrated in Larderello, where natural emissions have disappeared. The key finding is that both natural and plant emissions must be measured to accurately assess the total CO₂ balance in geothermal regions. Moreover, CO₂ flux measurements—both diffuse and focused—can serve as a practical tool for identifying and evaluating geothermal fields for future development. |