Combined heat and power from hydrothermal geothermal resources in Germany: An assessment of the potential

This study investigates the potential of hydrothermal geothermal energy for combined heat and power (CHP) generation in Germany. Based on the theoretical potential of hydrothermal heat in place, the technical and economic potential is determined with a review and an analysis of existing geothermal plants. To this end, the thermodynamic and economic performance of operating power plants is analyzed and models for the efficiency and the production costs are developed. Based on this analysis, a technical potential of 12.2 PWh(el) and 16.7 PWh(th) as well as an economic potential of 9.1 PWh(el) and 12.5 PWh(th) is determined. In order to derive an annual contribution from the economic potential, the regeneration of the resource is taken into account. Considering a sustainable exploitation rate, an annual economic potential of 9.1 TWh(el)/a and 12.5 TWh(th)/a is derived. This corresponds to a share of 1.51% of the gross electricity demand and a share of 1.48% of the demand for space heating and domestic hot water. This analysis provides a profound review about the existing geothermal power plants and their thermodynamic and economic performance. Furthermore, the assessment of the geothermal potential in Germany is necessary for political decision making, particular with a view towards future adjustments of the feed-in tariffs defined by the Renewable Energy Act.