Keywords: geothermal energy, hot-dry-rock-technology, geothermal heating systems, district heating, electricity generation, energy economics
Utilisation of deep geothermal energy for heating purposes
The Hot-Dry-Rock-(HDR) technology allows a location-independent utilisation of geothermal heat, because aquifers in deep formations, i.e. layers filled with water, are not necessary. The flow paths for the circulating water in a depth of 4 km are created by hydraulic fracturing of existing gaps. Due to the fact that this new technology is quite cost-intensive, high annual load duration of the energy system above the surface is needed for an economic operation. Therefore, a process of electricity production by using low temperature steam (Organic-Rankine-Cycle (ORC) or Kalina-Cycle) or a plant for the supply of thermal heat and hot water could be installed. Under reference conditions the average geothermal heat output amounts to approx. 7 MW and the investment costs are nearly 30 million EUR. At present, a feasibility study is accomplished to verify the technical and economic feasibility as well as the standards and chances of this technology. This study is financed by the federal state of North Rhine-Westphalia and the European Union.