| Authors |
Guido CAPPETTI, Nadia GIORGI, Alessia ARIAS, Gianni VOLPI, Germain RIVERA, Maurizio CEI, Maurizio FEDELI, Giuseppe DI MARZIO, Martino PASTI, Stefano MASSEI, Francesco BACCARIN |
| Abstract |
Cerro Pabellón is one of the most challenging geothermal project so far developed worldwide. Located in the northern part of Chile, 120 km north-east of Calama city (Antofagasta region), on the Pampa Apacheta, it represents the first commercial power plant in South America and is also the first utility-scale geothermal plant built worldwide at 4,500 meters a.s.l.. The geothermal field is located in a volcanic area, beside the Apacheta-Aguilucho volcanic complex, in correspondence of a well-defined graben structure characterized by a recent volcanic dome (about 50.000 yrs.). Since the geothermal field is considered as blind – with only two volcanic fumaroles on the top of Cerro Apacheta – a shallow borehole (187 m depth) drilled by Codelco (Corporación Nacional del Cobre, Chile) for water research represented the main indicator to activate a geothermal project, as it found steam (88°C) instead of tapping the expected cold water aquifer. In this area, the complete exploration and development of the geothermal project was conducted by Geotérmica del Norte (GDN), starting in 2002 with the assignment of the exploration mining lease (330 km2). During all the phases of the project, a great attention was put both in the environmental aspects and in the relations with local communities, in a logic of sustainable development. After a phase of shallow exploration surveys (geology and geophysics) and a corehole of 560 m depth, four deep commercial diameters exploratory wells were drilled in 2009-2010, showing the presence of a geothermal reservoir with temperatures of 250-260 °C at depths over 1500 m. According to these positive results, a development program was implemented, including the drilling of additional wells for production and reinjection purposes, the construction of a power plant, the gathering system and 80 km high voltage transmission line (220 kV) that connects the plant to the main transmission network. Because of the remote location and the extreme characteristics in terms of altitude and climatic conditions, a project’s base camp was built about 25 km from the project area at an elevation of 3,850 m a.s.l., powered by an innovative system of photovoltaic energy production and storage. The construction activities of the Cerro Pabellón project began in July 2015 by GDN and in March 2017, the plant started its commissioning phase. The 48 MWe gross ORC power plant is composed of two twin units (24 MWe each) and represents one of the few examples of high enthalpy binary power plant in the world, selected in accordance with the resource characteristics and with the extreme climatic operating condition. Cerro Pabellón will avoid the emission of more than 166,000 tons of CO2 into the atmosphere per year and it will contribute to diversify Chile's energy mix and to mitigate the country's dependence on fuel imports. Considering that the fluid production and the reinjection capabilities currently available from existing wells exceeds the power plant capacity, the construction of an additional 33 MWe gross unit, same binary cycle type, is scheduled to start in the second half of 2019. |