CEGA students seeking to clear up geothermal uncertainties

Monday, 26 de September

The geothermal potential figures that are handled today in Chile range from 3,350 MW (ENAP) to 16,000 MW (Lahsen, 1988), which could represent 91% of the current installed capacity of the country’s energy matrix. So far, this auspicious figure has not been updated, and therefore, PhD, masters and undergraduate students at the  Fondap-Conicyt Center of Excellence in Geothermal Andes are working to modernize this data based on a methodology designed to estimate geothermal resources volcanic systems associated unexplored. Along with this, prepare a map to determine the most favorable areas to exploit the resource. The idea has already been tested on a small scale in the area of El Maule, which showed a potential of 1,400 MWe for that region.

That geothermal energy is the most abundant renewable energy source in Chile, that Chile is the country with the largest untapped geothermal potential in the world. Chile: geothermal country, but, how much we mean by high geothermal potential in our country? What are the most favorable regions to exploit this resource? “There is no standardized procedure for estimating geothermal resources associated with unexplored volcanic systems, there is no long-term plan in order to identify and characterize the geothermal prospects and, at present, the Andean volcanic arc represents one of the largest geothermal provinces undeveloped in the world” says Diego Aravena, CEGA master student, who began developing an evaluation methodology from his undergraduate thesis, which has perfected in his master’s study and research parallel to their joint work with Pablo Sanchez, PhD student, and Ignacio Villalon, Geology undergraduate student. This, in order to refresh the figure that 20 years ago Alfredo Lahsen, Aravena teacher guide and a pioneer in the investigation of geothermal resources of the country, estimated for Chilean geothermal (16,000 MW).
Geothermal in Chile: where and how much
The work that this group of students performed jointly today was born from Aravena undergraduate research, where he tested the methodology for developing both a favorability map and calculating potential for the Maule Region. In this work he created a map indicating areas of geothermal interest, constructed from six layers of information: evidence of recent volcanic rocks, proximity to eruptive centers, proximity to areas with surface geothermal manifestations, fault density, mineral alteration zones identified by remote sensing, and high or low density of shallow earthquakes. As a result of this work Aravena created a geothermal favorability map for Maule Region, which confirmed the high favorability correlated with proximity to eruptive centers. Furthermore, to calculate the potential in this area he applied a methodology for evaluating geothermal energy reserves associated with volcanic systems: “By estimating the volume of the volcano a magma chamber volume is estimated, and by certain heat conductivity equations one can estimate how the temperature will be and how it will evolve over time“, says Aravena, who by that calculation estimated a potential for that region of 1,400 MWe, with 90% probability.

Ahora, Aravena junto a Pablo Sánchez e Ignacio Villalón, quieren llevar esa experiencia a escala país: “Para todas las energías en Chile hay un mapa donde se diferencias las zonas con más y menos recursos”, dice Sánchez, “por fin vamos a tener un mapa para conocer las zonas más favorables para la exploración geotérmica, una herramienta que reúne cuatro elementos primordiales: contar con fuente de calor, nivel permeable, red de fallas y fracturas y recargas de aguas meteóricas y subterráneas. Antes las estimaciones se basaban mucho en el tema de los volcanes activos, porque se conocían menos antecedentes de los que podemos reunir  hoy, y este mapa junta más variables que son clave”, explica.
El trabajo de Ignacio Villalón ha sido significante para la obtención de los dos productos que próximamente este equipo espera  dar a conocer a la comunidad. Motivado por involucrarse  desde su primera práctica en la investigación geotérmica, Villalón trabajó este verano junto a Diego y Pablo reuniendo datos sobre 109 volcanes activos de Chile, información que estaba dispersa en muchos registros y que Ignacio consolidó en una base de datos. “Al final de mi práctica entregué todos los volúmenes de los volcanes y el mapa de factibilidad de todo Chile. Ahí Alfredo Lahsen me insistió en que tenía que seguir trabajando en este tema y este primer semestre he estado con mi Proyecto 1 relacionado a la estimación de potencial. Trabajando con el código de Diego, lo arreglé para aplicarlo a todo Chile y basta pulir un poco eso y podremos calcular un potencial geotérmico para todo el país”, adelanta Villalón.
Es de esperar que ambos trabajos estén disponibles en su versión final durante este año. Por ahora, es un buen momento para aventurarse con apuestas: ¿Se superará o se derribará la barrera de los 16.000 MW?

Text: CEGA – sotero@ing.uchile.cl