The progress of geothermal knowledge at Larderello, Italy

We reviewed the historical process that led to the present knowledge of the Larderello geothermal system. This long journey through the human benefit of geothermal resources started in pre-historical times, with the fundamental needs to have warm areas for living, and chemical compounds, i.e., hydrothermal minerals, to exploit. The Larderello area is this: a historical site that evolved to the Present state, passing to be the birthplace of the modern geothermal-electrical industry and today one of the most productive fields in the world. Current knowledge comes from close collaboration between industry and research centres, being a key factor in improving the understanding of the relationships between geological structures and geothermal fluid flow in industrial terms. Due to the efforts of researchers, the evolution of the tectonic and hydrological setting has been revealed: circulating fluids were initially strongly influenced by magmatic and contact-metamorphic supplies, resulting meteoric in the late stage. Permeability is promoted by transfer faults and intersections with coeval normal faults, defining the Miocene-Pliocene Lago pull-apart Basin. In this area, the higher values of heat flow, mantle He isotopes, and shallow depth of the current magmatic source are concentrated, making it one of the most productive field. We conclude underlining the key-role of Earth sciences and of an interdisciplinary approach to face the new challenges of geothermal exploration and sustainable use of geothermal resources.