Life cycle assessment of enhanced geothermal systems : from specific case studies to generic parameterized models.

Summary This research aims to study the environmental impacts of an emerging renewable-based electricity generation technology, geothermal stimulated systems (GS), through life cycle assessment (LCA).After analyzing several case studies, we developed a parameterized LCA model capable of characterizing the environmental performance of the GS system. Our results show that the life cycle greenhouse gas emissions of EGS are much lower than those of fossil fuel power plants.In a second step, we developed a methodological framework to apply global sensitivity analysis (GSA) to the LCA of emerging technologies such as EGS, taking into account the high uncertainties related to their innovative character. We have applied our new GSA approach to develop a simplified LCA model for decision makers, allowing a quick estimation of the impacts of EGS from only five key parameters: installed capacity, drilling depth, number of wells, geothermal flow rate and lifetime.The methodological approach developed in this thesis is applicable to other technologies and opens up broad research perspectives in the field of environmental assessment.