Thermoeconomic comparison of designs for geothermal combined heat and power generation

Abstract

In this paper different power plant designs for geothermal power and heat generation are examined under thermodynamic and economic aspects. For quasi steady-state simulations the heat demand is calculated according to reference load profiles of single-family and multi-family houses, which are approximated by discrete load steps. Based on standard conditions sensitivity analyses concerning heat demand, supply temperature, ORC working fluid and geothermal water temperatures are performed. The results show that the hybrid power plant is the most efficient concept for combined heat and power generation. The choice of ORC working fluid is important for geothermal water temperatures higher than 120 °C. Regarding economic aspects the cumulated cashflow obtained by the hybrid power plant is 77 % higher compared to single power generation. The supply temperature of the heating network has a significant influence on thermodynamic and economic efficiency.