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GRC Transactions, Vol. 35, 2011

Current Status of Geothermal Exploration in and the Role of the New Andean Geothermal Center of Excellence (CEGA)

Pablo Sánchez, Diego Morata, Alfredo Lahsen, Diego Aravena, and Miguel Ángel Parada Departamento de Geología and Centro de Excelencia en Geotermia de los [email protected]

Geothermal History Keywords Chile, exploration, geothermal update, Andean, CEGA, history The interest in geothermal energy in Chile dates early 20th cen- tury, when Italian researchers arrived to asses Andean resources. At that time (1908), members of the Italian colony of Antofagasta Abstract created a private society to carry out the first geothermal explo- ration program in the country. During the period 1921-1922, an The Andean volcanic arc hosts more than 200 active volcanoes, Italian technical group from Larderello drilled two wells of about some of which are related to proved geothermal resources that 70-80 m depth (Lahsen, 2005). could provide clean and sustainable energy in Chile. Even though One of the most fruitful periods of geothermal exploration exploration campaigns started in the early 20th century, the Andes began at the end of 1960s, when the Chilean State promoted still represents one the largest undeveloped geothermal regions of research in the northernmost part of the country (17° to 24°S), the world (Lahsen, 2005). However, this situa- oriented to supply energy for mining tion will change shortly. In Chile, geothermal process. This was possible through a col- exploration is currently very active and involves laborative project between the Chilean the participation of more than ten national and Development Corporation (corfo) and international companies in more than forty the United Nations Development Program geothermal areas, with the aim of developing (undp), which was agreed towards the end geothermal resources. One of the reasons for of 1968. In this project, a reconnaissance the renewed interest in geothermal resources is survey was done in many geothermal areas, the increasing need of new national sources of while detailed geological, geochemical energy, taking into account the high dependence and geophysical surveys in selected areas on imported fossil. In that regard, the Renewable (Suriri, Puchuldiza and El Tatio geother- Energy Law of 2008 forces that 20% of all gener- mal fields) were carried out until 1976. ated electricity comes from renewable sources They were followed by basic geological, by 2020. The Geothermal Law of 2000 provided geochemical and volcanological surveys also a clear and easily managed framework for in many geothermal areas, the drilling of the exploration and development of geothermal exploratory wells, and feasibility studies energy. A new impulse for the development of for power generation at El Tatio and Pu- geothermal energy is the creation of the Andean chuldiza (Lahsen, 1976). Geothermal Center of Excellence founded by From that point, basic volcanological Chilean government, with the mission of gen- and geochemical studies in the geothermal erating and improving geothermal knowledge areas have been occasionally conducted by in Chile and the rest of the Andean countries. the University of Chile, foreign institutions In this paper we present the latest advances and the National Geological Survey of Chile in geothermal exploration and the new estima- (sernageomin), in many geothermal areas tions for midterm power generation. We finally (e.g. Lahsen, 1986, 1988; Hauser, 1997). introduce the Andean Geothermal Center of The state-owned oil company (enap), in Excellence to the geothermal community Figure 1. Active volcanic zones of northern collaboration with other companies, resumed worldwide. and central-southern Chile. geothermal exploration in the country between

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1995 and 1999. In 1995, a 274 m deep slim exploratory well was drilled in the Nevados de Chillán geothermal area and encountered wet steam with a temperature of 198°C (Salgado and Raasch, 2002). A new period started in 2000 when the Chilean government enacted a Geothermal Law providing the framework which pro- motes private companies (international and domestic) to develop exploration and exploitation of geothermal resources in Chile. State-owned companies, as ENAP, must thus be associated with a private company to participate in the business. The law also establishes the existence of exploration and exploitation conces- sions which are granted by the Ministry of Mines. Exploration concessions are valid for two years and may be extended for fur- ther two years. Exploitation concessions give the exclusive right to own all the geothermal power and brines, to use the land and to transfer or sell it without any limitation (Lahsen et al., 2005). As a result, the geothermal exploration and development are currently very active, with more than 45 geothermal areas being assessed by more than 10 companies. Some of the identified barriers to develop geothermal projects are the limited scientific knowledge on geothermal systems in the Andes and the limited number of professionals specialized in geothermal energy. During the last decade, sernageomin is doing detailed geological studies in the geothermal areas for which geological maps are not available. Also a new impulse to improve geothermal knowledge in Chile constitutes the creation of the Andean Geothermal Center of Ex- cellence (cega), founded by the Chilean government since 2010. Figure 2. Geothermal areas of the central-southern Chile.

Geothermal Resources Over 300 thermal features, ranging from hot springs to super- heated fumaroles, are concentrated along the axis of the Chilean Andes, mostly associated with Quaternary volcanism (Hauser, 1997; Lahsen, 2010). These are mainly distributed within the margin-parallel Central Volcanic Zone (17–27°S) in Northern Chile and Southern Volcanic Zone (33–46°S) in Central Southern Chile, distinguishable in the Chilean Andes (Fig. 1). In areas where the Quaternary volcanism is absent, such as along the volcanic gaps of Andean Cordillera (28°-33° and 46°-48°S), as well as in the Coastal Range, thermal springs are scarce and their temperatures are usually lower than 30°C (Hauser, 1997; Lahsen et al., 2005). In the Northern volcanic-geothermal zone there are about 90 thermal areas with sodic-chloride waters. They are mainly located within NS-, NW-trending grabens in the western side of the volcanic arc. The hydrothermal reservoirs are mainly located in Meso- Cenozoic volcano-sedimentary formations underlying Holocene volcanoes. Geothermometry suggests that El Tatio and Puchuldiza- Tuja fluid reservoirs have relatively high reservoir equilibrium temperature (up to 270 °C) and Pampa Apacheta is equilibrated at unusually high temperature (up to 350 °C) (Tassi et al., 2010). In the Central-Southern volcanic geothermal zone there are more than 150 geothermal areas, which are related to active vol- canoes and/or structural systems. From 33° to 34°S, most of the thermal areas are associated with the Pocuro fault system, where Upper Cretaceous and Tertiary volcaniclastic rocks are dominant (Hauser, 1997). Between 39° and 46°S, geothermal activity is related to LOFZ, a 1,200 km long intra-arc dextral strike-slip fault system. Secondary permeability allows deep fluid circulation into high heat flux areas of the Patagonic Batholith resulting in Figure 3. Geothermal areas of the central-southern Chile.

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Table 1. Main geothermal exploration projects, their geothermal context and current status. Geological data from (1) Lahsen, 1976; (2) , 2008 (3) Smithsonian Global Volcanism Program; (4) Benavente et al., 2011; (5) Dixon et al., 1999; (6) Melosh et al., 2009. Location Geothermal Eleva- Surface Activity Geologic Current Activities Lat Long Company Area tion and temperature Enviroment in Exploration Puchuldiza 1 19°23'S 69º01'W 4250 Hot springs, fumaroles, mud Volcano-tectonic depression surrounded Slim holes have GeoGlobal Energy pools, altered zones, silica de- by Plio-Pleistocene volcanoes (1) been drilled posits, boiling pools ; 20-90 ºC Apacheta 21°51'S 68º08'W 5200 Fumaroles; 118ºC Plio-Pleistocene volcanic complex lo- Planning production Geotérmica del Norte cated within a NW-trending graben (2). for 2014-2015 Surire - 18°55'S 68º59'W 4300 Fumaroles, hot springs, altered Plio-Pleistocene dacitic volcanoes (1) Slim holes have Energía Andina S.A. Polloquere 1 zones, silica deposits, boiling been drilled pools ; 20-80 ºC 20°44'S 68°33'W 5150 Fumaroles, hot springs; >100ºC Stratovolcano within a NE-SW-trending Slim holes have Minera Doña Inés chain of volcanoes constructed within been drilled de Collahuasi the collapse scarp of a Holocene debris avalanche (2), (3). Pampa 19°51'S 68º56'W 3900 Geysers, hot springs, fumaroles, Upper tertiary sedimentary and Surficial exploration. Energía Andina S.A. Lirima altered zones,deposits, boiling volcanic rocks (1) Slim holes drilling pools ; >86 ºC are planned El Tatio 22°20'S 68º`01'W 4300 Geysers, hot springs, fumaroles, N-S graben filled by Miocene to Current exploration Geotérmica del Norte mud pools, altered zones, silica Pleistocene ignimbrites and andesitic stopped. deposits, boiling pools ; 86 ºC volcanoes (1) Tinguiririca 35°48'S 68º00'W 4200 Hot springs, fumaroles Holocene scoria cones constructed Slim holes have Energía Andina S.A. along a NNE-SSW fissure over an been drilled eroded Pleistocene stratovolcano (3) 35º30'S 70º30'W 2600 Hot springs, fumaroles, mud Plio-Pleistocene basaltic to dacitic Slim holes have Empresa Nacional pools, altered zones ; 20-90 ºC volcanoes. (4) been drilled de Geotermia S.A. Laguna del 36º01'S 70º35'W 2400 Fumaroles, hot springs, steam- Basaltic to riolitic Holocene volcanoes Slim holes have Compañía de Energía Maule ing ground, bubbling pools; and blocky lava flows (4) been drilled Limitada 93º-120ºC Chillan 36°51'S 71°22'W 3200 Fumaroles, hot springs, mud N30W trendind basaltic to dacitic Current exploration Empresa Nacional pools, altered zones; 90ºC late Pleistocene to Holocene volcanic stopped. Slim holes de Geotermia S.A. complex (5) have been drilled. Tolhuaca 38°18'S 71°38'W 2700 Fumaroles, hot springs, propy- Volcanic flows and breccias near the Planning production GeoGlobal Energy litically and argilically altered inactive late-Pleistocene to Holocene for 2015 zones; 49 ºC Tolhuaca Volcano (6) sulfate-alkaline thermal waters (Alam et al., 2010). However, high In Northern Chile, areas where exploration slim holes have enthalpy geothermal features, as fumaroles are related to active been drilled are Apacheta, El Tatio, Surire - Polloquere, Puchul- volcanism, where acidic-sulphate, bicarbonate and chloride type diza and recently Irruputuncu (Figure 2; Table 1). At Apacheta waters are present. Geothermometry in Calabozos, Nevados de and El Tatio geothermal areas, 4 holes have been drilled up to Chillán, , Sierra Nevada and Puyehue-Cordón Caulle depth of 1,700 meters. Preliminary estimation of the potential of ranges between 200 and 250°C for water. these areas is between 400 and 1,000 MWe. Preliminary results A preliminary assessment of the geothermal potential of the from the drilled holes indicate a potential of 5-10 MW per well country is in the order of 16,000 MW for at least 50 years, con- (Lahsen et al., 2010). Geotérmica del Norte geothermal company sidered from the geothermal fluids with temperatures exceeding has submitted the Apacheta project to the environmental system 150°C, and located at a depth less than 3,000 m (Lahsen, 1986). An for the construction of a 40 MW flash power plant and a 10 MW update of the Chilean geothermal potential using new techniques binary power plant to be producing in 2015. will be available during 2012 in charge of CEGA. In the Central-Southern areas following slim holes have been drilled: Tolhuaca, Calabozos, Chillán, Laguna del Maule and Tin- Geothermal Projects Update guiririca, with a potential estimated of 3-10 MW per well (Fig. 3; Table 1). At Tolhuaca, two holes have been drilled up to depth of At 2011, around 40 exploration and 6 exploitation concessions 1,200 meters and a 50 MW geothermal power plant is planned have been given to companies. All of these areas have some surfi- to start production on 2013. Potential is estimated in 600 MWe cial indicator and the current analysis involves geological surveys, to 950 MWe in this area (Lahsen et al., 2010). New slim holes volcanological studies, geophysical, geochemical surveys and also will be drilled at Puchuldiza, Polloquere, Pampa Lirima, Colpitas detailed exploration using drilling tools. Exploitation concessions and Juncalito by Energía Andina which plan to have a geothermal involve drilling production wells (Table 1). plant working in 2015.

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The Andean Geothermal Center References of Excellence (CEGA) Aguilera, F., 2008. Origen y naturaleza de los fluidos en los sistemas vol- cánicos, geotermales y termales de baja entalpía de la Zona Volcánica Central entre los 17°43´S y 25°10´S, Chile. Ph.D. Thesis. Universidad The Andean Geothermal Center of Excellence (CEGA) Católica del Norte. (In Spanish) hosted at the University of Chile has the mission to provide the scientific background to model geothermal reservoirs in Alam, M.A., Sánchez, P., Parada, M.A., 2010. Interplay of volcanism and structural control in defining the geothermal system(s) along the Liquiñe- Chile and the rest of the Andean countries, with the purpose Ofqui Fault Zone, in the south-central Chile. Geothermal Resources to develop geothermal energy as a sustainable, environment- Council Transactions v. 34, 747-750 friendly and economically competitive alternative to the energy Benavente, O., Gutierrez, F., 2011. Hydrothermal systems associated to requirements of Chile and Latin America. To meet this objec- Planchón Peteroa and -Quizapu-Cerro Azul Volcanic tive, the Center will aim to: (a) improve and expand scientific Complexes. Geothermal Resources Council Transactions, this volume. knowledge on geothermal resources in Chile and the Andes, Dixon, H.J., Murphy, M.D., Sparks, S.J., et al., 1999. The Geology of Nevados (b) train undergraduate and graduate students at the highest de Chillán Volcano, Chile. Revista Geólogica de Chile, 26, N°2. 227-253. level, (c) generate a new “in-house laboratory culture” by lo- Hauser, A., 1997. Catastro y Caracterización de las Fuentes de Aguas Mi- cally generating results in state-of-the-art analytical facilities, nerales y Termales de Chile, SERNAGEOMIN, Bulletin N° 50, 90 p. (d) promote collaborative geothermal research between the (In Spanish) Centre and other academic institutions, as well as industry, Lahsen, A., 1976. Geothermal exploration in Northern Chile - Summary. Cir- and (e) identify and evaluate new and emerging technologies cum-Pacific Energy and Mineral Resources.AAPG Memoir v. 25, 169-175. for geothermal assessment and exploration. Six main research Lahsen, A., 1986. Origen y potencial de energía geotérmica en los Andes de lines would be developed by the CEGA: Magmatic Systems, Chile. In: J.Frutos, R. Oyarzún, and M. Pincheira (Eds) Geología y Re- Heat-Water-Rock Interactions, Fluid Geochemistry, Reservoir cursos Minerales de Chile, Univ. de Concepción, 423–438. (In Spanish) Architecture & Geofluid Dynamics, Structure, Tectonics & Geo- Lahsen, A., Sepúlveda, F., Rojas, J., Palacios, C., 2005. Present Status of physics, and Surficial Processes & Environment. The CEGA is Geothermal Exploration in Chile. Proceedings World Geothermal Con- gress, Antalya, Turkey. supported by the Chilean CONICYT-FONDAP Program during five years, extendible to five more. Lahsen, A., Muñoz, N. and Parada, M.A., 2010. Geothermal Development in Chile. Proceedings World Geothermal Congress, Bali, Indonesia Melosh, G., Cumming, W., Sussman, D., et al., 2009. Rapid Exploration of the Tolhuaca Prospect, Southern Chile. Geothermal Resources Council Acknowledgements Transactions v. 33, 505-508 We are grateful to Jorge Clavero from Energía Andina, Car- Salgado, G. and Raasch, G., 2002. Recent geothermal industry activity and the market for electric power in Chile. Geothermal Resources Council los Ramirez from ENG and Diego Gaytán from Hot Rock who Transactions v. 26, 55–58. provides us updated information on projects. We would also like Tassi, F., Aguilera, F., Darrah, T., et al., 2010. Fluid geochemistry of six to acknowledge the support of CONICYT FONDAP Project hydrothermal systems in the Arica-, Tarapacá and Antofa- 15090013 “Centro de Excelencia en Geotermia de los Andes, gasta regions (northern Chile). Journal of Volcanology and Geothermal CEGA”. Research, v. 192, 1-15

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