Geothermal Energy Resources of Madagascar - Country Update

Abstract

The overall objective of the study is to develop geothermal energy to complement hydro and other sources of power to meet the energy demand of rural areas in sound environment. The exploration of geothermal energy in Madagascar is still at an early stage. In last recent years, the researchers from our university evaluated their geothermal resources using geology, geochemical data analyses and geophysical measurements. The preliminary results of this exploration indicate that about 130 natural geothermal outcrops are recognized in the country. The distribution of thermal springs, heat flow and the nature of the geothermal reservoirs are controlled by the geological structures. The geothermal areas can be divided in three sections: volcanic terrain, fault zone, and sedimentary basin. Resources and geothermal systems are of two types: volcano-tectonic and tectonic. Concerning the possibility of electrical geothermal energy production, Madagascar is believed to have a geothermal potential which is estimated to be in excess of 350 megawatts and it presents a huge number of medium and low enthalpy geothermal zones of interest. Geothermal systems of medium temperature exist in the recent volcanic area and the possibility of drilling into a medium temperature geothermal reservoir is high, especially in the north and the central part of the country. Subsurface temperatures of approximately 60-155°C for the northern zone of the island, 92-154°C for Itasy and 87-171°C for Antsirabe-Betafo have been predicted by geothermometry and mixing models. Geophysical measurements to locate the deep reservoirs and drill sites in the three areas are recommended. The results will then be used to update the geothermal models that will be a basis for the drilling of deep geothermal wells. Despite the availability and enormous potential in direct use applications, little use has been made of low to medium enthalpy fluids in Madagascar. These thermal phenomena are still not developed and their exploitation is limited. Currently, geothermal water is used for bathing, swimming, balneology, tourism and washing with little economic return. An overview of the energy sector, a review of the geological background, known geothermal resources and their potential and present geothermal utilization are given in the paper.