Analysis and development of new techniques and possibilities of using Geothermal Energy

Resumen

Renewable energies have got an essential role in the continuous climate change mitigation. The present-day society requires the implementation of green energy sources with the principal aim of reducing the fossil’s fuels use. Within the broad spectrum of renewable energies, geothermal energy constitutes an important part for a future sustainable development. Depending on its thermal and geological characterization, the use of this energy is directly related to the generation of domestic hot water and/or heating/cooling purposes. Electricity production could be also included as a geothermal application if the geological conditions of the resource allowed it. There is a large number of advantages that define this kind of renewable source (e.g. continuous use, reduced greenhouse gases emissions, minimum operational costs, geological independence for heating and cooling uses, etc.). However, the high initial investment commonly required for domestic installations and the lack of knowledge in the field, make the use of this energy limited in certain occasions. The present Doctoral Thesis is framed within the analysis and evaluation of the principal parameters and components that, directly or indirectly, influence the development of low enthalpy geothermal systems. Specifically, the main goal of this research work is to define the most optimal schema of geothermal operation that helps to contribute in a more extensive use of this renewable technology. The research lines include extensive field work and laboratory tests, in addition to the computing processing and analysis of the experimental and simulation data. The starting point of the research work was the identification of the weaknesses that characterize low enthalpy geothermal resources. After this first evaluation, efforts were focused on the realization of different tests on the parameters detected as essential in the previous stage. Experimental work was complemented with the use of specific software on the basis of the geothermal systems dimensioning, energy simulation and modelling apart from the corresponding numerical and theoretical studies. Conclusions obtained from the whole practical and theoretical work allowed establishing the most optimal geothermal methodology. In summary, the present Doctoral Thesis contains valuable information that has been compiled in numerous scientific works in which all the know-how and expertise arising during this research stage have been compiled.