Evaluation of different ORC power plant concepts for geothermal heat and power generation.

Abstract

In this work, different geothermal heat and power generation concepts are evaluated under techno-economic aspects. The investigated solutions cover different geothermal conditions and ORC power plant technical features available in Germany. The evaluation is based on annual simulations by using Aspen Plus V8.8. For the heat demand, a peak load of 5 MW is assumed. In case of a geothermal well-head temperature of 135 °C, the double-stage ORC shows a second law efficiency of 38.5 %, while the one-stage concept leads to 33.1 %. In general, the analysis shows that the technically more challenging ORC concept leads to a higher amount of produced electrical energy and to a lower levelized cost of electricity (LCOE). For instance, the double-stage ORC provides a higher turbine power output than the one-stage. In addition, an economic analysis shows that the double-stage concept leads to a slightly lower LCOE of 13.79 €ct/kWh compared to the one-stage ORC. The results enable operators and planners to identify the most suitable power plant configuration in dependence of reservoir conditions and specific heating demand.