One of today’s greatest challenges is the energy transition from fossil fuels to low-carbon renewables. Geothermal energy is a local solution for base load heat and electricity supply. As such it has the potential to provide safe and clean energy for the growing urban areas worldwide. However, most of this heat is stored in deep formations with low permeability. Reservoir engineering methods that improve subsurface fluid pathways are therefore essential to utilize this potential. Because these methods are still under development, they often do not yield the required hydraulic performance and pose the risk of fluid-induced seismicity. This is the reason for the limited share of geothermal in today’s energy-mix. The objective of the Helmholtz Young Investigator Group ARES is the development and verification of advanced geothermal reservoir engineering concepts for a controlled and commercially viable development of deep geothermal energy as a local base load energy source for district heating in urban areas. The research focus is on sustainable productivity enhancement with reduced seismic risk. To achieve this goal a multi-scale approach is pursued. That includes laboratory, mine and field scale experiments in different geological settings, accompanied by theoretical considerations, modeling and upscaling.