Thermoeconomic evaluation of one-and double-stage ORC for geothermal combined heat and power production

Abstract

We present a thermoeconomic analysis of potential concepts for a combined heat and power generation (CHP) in case of a geothermal heat source. Based on the double-stage Organic Rankine Cycle (ORC) power plant in Kirchstockach (Germany) various strategies for an additional heat generation are examined. For the calculation of the ORC part load behaviour, real power plant data are analysed. Alternatively, a one-stage ORC is considered as a power unit. Regarding the heat demand, a reference load profile for a residential area consisting of single-family and multi-family houses underlies the case study. The results show a higher efficiency for pure electrical power generation as well as for CHP based on the double-stage ORC. In particular, for low supply temperatures of the heating network, CHP could lead to additional revenues up to 1.1 Mio€/a for the examined scenario compared to pure electrical power generation.