The low speed ORC process has an electricity output of 400–1100 kW and electricity to heat ratio of 0.18–0.22. The ORC-concept has two circuits, one for thermal oil and another for organic fluid.

The range of the electrical power output is from some kilowatts to about 10 MW. Additionally, thermal energy can be produced, which does increase the overall efficiency. Due to the low temperatures, ORCs possess a lower theoretical Carnot efficiency at a maximum of 30% [1] than water/steam cycles.

The Rankine (°R) scale is the absolute temperature scale related to the Fahrenheit (°F) scale, and both scales have the same size unit of temperature. The two scales are related by the equation °R = °F + 459.67. The freezing point of water occurs at 491.67 °R, whereas its boiling point occurs at 671.67 °R.

The working principle of the organic Rankine cycle is the same as that of the Rankine cycle: the working fluid is pumped to a boiler where it is evaporated, passed through an expansion device (turbine, screw, scroll, or other expander), and then through a condenser heat exchanger where it is finally re-condensed.