Abstract

Renewable energy has become a possible alternative to solve the energy and environmental problem in Chile and worldwide. Low enthalpy geothermic energy might satisfy the need of energy consumption for heating, which is a critical issue in the Center and South Regions of Chile. The characterization of the geothermal resource is fundamental for an efficient and sustainable extraction of heat. In this study a geothermic characterization of two representative soils from Concepción, namely Bío Bío sand and Maicillo, was carried out. Bío Bío sand is a uniform and clean sand which is mainly constituted by basaltic particles, whereas Maicillo is a silty and clayey sand with a high content of quartz. Prepared samples of both soils were tested with a single and double thermal needle probe at different water contents and compaction index. Measurements of thermal conductivity and volumetric heat capacity of 16 samples of each soil were carried out. These results allowed the correlations between geotechnical and heat transfer parameters. It was found that Maicillo has better capabilities to transfer heat than Bío Bío sand due to its quarzitic mineralogy and non-uniform grain size distribution characteristics. This difference is probably owing to the Maicillo higher clay particle content, the physical property of adhering water, quarzitic mineralogy and a less uniform grain size distribution.