Economic Evaluation of Geothermal Combined Heat and Power Concepts

Abstract

Heating and cooling is almost the half of the global energy consumption and the market volume is expected to rise significantly in the next years. Therefore, flexible systems producing heat and power will gain more interest in the future. In this study, an economic evaluation of the geothermal heat and power generation is proposed. For the evaluation the net present value (NPV) is calculated and compared to the reference case of pure power generation. To calculate the NPV, annual simulations are conducted based on a double-stage Organic Rankine Cycle and geothermal conditions in southern Germany. For the district heating network (DHN), a supply temperature of 90 °C and a return temperature of 60 °C is assumed. The peak load of the DHN is varied the range of 5 MW to 20 MW. Furthermore, different areas of the DHN are considered: an inner city DHN and a DHN in a development area. In addition, the commissioning year of the plant is varied. The results show that for an inner city DHN the profitability of geothermal power plants can be increased by additional heat generation for all considered peak loads. For a 15 MW peak load of the DHN, the NPV is 115.3 million € and 11.0 % higher than for pure power generation. For the DHN built up in a development area, in general, the NPV is higher than for inner-city DHN due to the lower investment costs. Regarding the commissioning year of the power plant, as expected the NPV is significantly lower for commissioning the plant in the future. However, this effect can be reduced by a higher peak load of the DHN.