GFZ is the national German Research Centre for Geosciences. GFZ combines all solid earth science fields including geodesy, geology, geophysics, mineralogy and geochemistry, in a multidisciplinary research centre. Research activities at the section "Geothermal Energy Systems" cover all processes and interactions underground and above ground in the fields of geothermal exploration, reservoir engineering and monitoring as well as process and power plant technology. Particular emphasis is given to the development of Enhanced Geothermal Systems and a sustainable storage of thermal energy in aquifers. Within the GeConnect project, GFZ mainly works on fiber optic sensing technologies for monitoring the performance of the flexible coupling and to validate an increased mechanical well integrity during temperature cycling experiments.