Integrating Multi Purpose Geothermal Systems with Local City Heating Grids

Abstract

Not only high heat flow regions with volcanic activity, but also other regions such as sedimentary basins are suitable for geothermal energy. In the Netherlands, with a low thermal gradient however, there are no governmental incentives for such developments, making geothermal heat and electricity production at best marginally economical. Therefore, smart solutions are needed as to economize geothermal systems, such as integration into existing heating grids, exploitation of synergies with fossil-fuel based systems, and innovation on well-construction technology. In the presence of existing grid-heating networks, geothermal heat can be included in the gross energy mix. By combining a geothermal system with a power/heat co-generation plant, a peak shaving effect on the economical risks of a combined investment can be created, making city heating grids more favourable. By combining the geothermal system with co-injection of CO2 captured from the co-generation plant it is possible to create an economically feasible, environmentally sustainable multipurpose energy system. To enable the drilling of deep geothermal wells in urban areas with limited operational space, new full composite casing drilling technology with back of the truck operations have been developed at TU Delft and local based companies. As the composite material is corrosion resistant, the co-injection of 15.000 ton CO2 annually becomes feasible without reducing the integrity of the wells.