The Geothermal Potential in Isla Campuzano, Nicaragua

Abstract: Nicaragua has a geothermal potential of 1519 MW (CNE 2001) due to its volcano chain created by the tectonic activity between the Cocos plate and the Caribbean plate. The Ministry of Energy and Mines in Nicaragua has the ambition to have 91% of Nicaraguas energy consumption from renewables energy for 2027 where geothermal energy will constitute 22%. In June 2016 an earthquake of magnitude 6.1 occurred in the region of Chinandega with an epicenter in Isla Campuzano. This volcanic activity led to an increase of the water level in the hot springs in the area which captured the attention of UNAN-Managua, IGG-CIGEO and led to this bachelor thesis. The aim of this work was to determine if there is a geothermal potential in the area of Isla Campuzano by performing a geochemical analysis in hot springs. Another objective was to asses the advantages and disadvantages of geothermal energy in Nicaragua.In order to estimate the geothermal potential field work, interviews, laboratory work, geological mapping and geochemical calculations were performed. To gain geological background information a geological mapping of the area was performed by using QGIS. The field study was conducted by first collecting 17 water samples at 6 different locations and measuring the pH, conductivity and temperature. Moreover, the concentrations of Na, Ca, K and SiO2 in the water samples were determined by an ICP-OES. The results showed high concentration of sodium which could be an indication that the water also contains high concentration of Cl which is characteristic for geothermal water. As the water samples were collected in superficial water the concentration of Ca was high and SiO2 low. The sub geothermal temperature used to determine the geothermal potential was calculated with two Na-K-Ca geothermometers: Fournier & Truesdell (1973) and Fournier (1981). Five out of six sampling locations showed a sub temperature between 110-200 °C. According to Sveinbjörnsson (2016) this temperature range means a medium enthalpy geothermal source, which can generate electricity through a binary power plant.The uncertainties from the results were that only six sam- pling locations were studied and four geothermal chemical indicators were analyzed, and therefore only two geothermometers were suitable to use. The results from these geothermometers showed a difference of 20°C. Additionally the geology and the geophysics of the area were not studied in detail. This means that the results can only be used as an estimation and further investigations in all three geosciences has to be done in order to confirm the results. From the interviews it was concluded that the main barriers of geothermal energy in Nicaragua is the difficulty of finding financial help for the projects and the overestimation of the potential due to technical errors. The main advantages are that it is a renewable energy source, with a high potential, a low variability meaning that no storage technology is needed. In conclusion, there is a geothermal potential of medium enthalpy in the area except for sam- pling location 1. In other words, there is a potential of generating electricity with a binary power plant. These results should be used as an estimation as only the geochemistry has been analyzed and only two geothermometers have been accurate to use. An investment on this type of energy in the area of Isla Campuzano could both lead to an improved infrastructure and positive development of the socio-economic situation.