Hybrid geothermal–fossil electricity generation from low enthalpy geothermal resources: geothermal feedwater preheating in conventional power plants

Hybrid steam power plants with geothermal feedwater preheating enable the conversion of geothermal energy into electricity in countries with low enthalpy geothermal resources. In order to estimate the potential of geothermal–fossil hybrid power plants with geothermal feedwater preheating, we examine the application of this concept using the examples of two modern coal fired power plants. In addition, energy output and economic efficiency calculations will be compiled for this concept utilising the thermal water data of an existing geothermal heating installation and an experimental facility for the hot dry rock technology. The process of geothermal feedwater preheating as a means of improving performance forms both an alternative and an extension to the existing electricity generation methods based on renewable energy. Photovoltaics or wind power, for example, tend to be expensive and also unreliable due to weather uncertainties. An electricity cost of around 85 EUR/MWh appears to be attainable through the geothermal preheating concept in Central Europe. In countries with the appropriate prerequisites, this concept heralds considerable benefits in terms of efficient electricity generation and environmental protection.