Until recently, small-scale, geothermal power generation has been inhibited by the relatively high cost of power plants. Geothermal power plant development has focused on units in the multi-megawatt range, while ignoring smaller heat sources.These smaller heat sources can be a great fit for smaller scale geothermal power generation using BEP‘s E-Rational. Depending on the heat source available, the E-Rational can be connected directly using the hot liquid, steam condensate, or as a bottom cycle of another process. The majority of geothermal resources has generally lower temperatures (less than 120 °C), and the E-Rational can operate at resource temperatures as low as 85 °C.


The E-Rational ORC transforms between 6–18% of low-temperature thermal energy, depending on the condensing temperature, to electricity.