Direct Utilization of Geothermal Energy for Space Cooling in Nicaragua
Author: Jón Sigurður Pétursson
Year: 2016
Supervisor: Einar Jón Ásbjörnsson
The project was conducted in cooperation with Iceland Geothermal Cluster.
Abstract
Direct use utilization of geothermal energy dates back thousands of years, but it wasn't until the 20th century that it was first harnessed for the generation of electricity. In recent times, direct utilization has diversified greatly, and there are multiple methods available for temperatures ranging from 20°C up to 180°C. One of these methods is to use the heat energy to drive an absorption refrigeration system (ARS) and produce chilled water for space cooling. This possibility is explored within this thesis with the country of Nicaragua in mind. An Memorandum of Understanding (MoU) has been signed between Iceland Geothermal and the Nicaraguan government for the development of a Geothermal Resource Park in the areas of Apoyo, Masaya and Mombacho. A master plan, published in 2001, found that up to 360 MW of electricity could be generated in these three areas combined. Nicaragua is a tropical country with high average temperatures (daily average of 30-33°C and night time average of 21-24°C) and space cooling in such temperatures is an important factor in the quality of life. The country is volcanically active and as a result has readily available geothermal heat. In order to evaluate an ARS, that utilizes geothermal waste heat as its driving force, the cooling loads for four types of buildings were evaluated. A model for calculating the internal state properties of an ARS and its energy flows is presented for the program Engineering Equations Solver (EES). A cost-benefit analysis comparing an ARS and a conventional compression chiller is presented, where the total annual costs are assessed. Results find that the ARS chiller is a more economically feasible option and provides a more secure supply of chilled water for air conditioning purposes. The lack of electricity infrastructure in the country further supports the use of a technology that is not as dependant on electricity as its driving force.