FlexGeo aims to develop innovative geothermal energy system designs for maximized systems performance and flexibility. Pathing the way for the market entry of commercial modular reversible ORC systems will be, together with advanced smart control strategies and operational tools, the backbone of our concept. The proposed key-innovations will make geothermal systems more flexible, more efficient, more economically viable and adaptable for an implementation and market update across Europe and beyond. A modular rev. 200 kWel ORC unit with advanced control strategies and operational tool will be installed and demonstrated at a real district heating system at the TUM Campus in Garching, Germany. The first-time demonstration of this innovative technology on a TRL 7 level will directly path the way to its market entry after the project, since due to the attractive modular approach, the demonstrator already has the same capacity as the future commercial product. Furthermore, innovative geothermal system designs considering high- and low-temperature Underground Thermal Energy Storage (UTES) systems, advanced closed-loop systems (AGS) and enhanced flexibility of district heating (DH) and district cooling (DC) networks (DHCN), are pathing the way to a broad spread of the FlexGeo solutions across Europe and the world, resulting in largescale CO2 emission reductions.