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.

The ORC-concept has two circuits, one for thermal oil and another for organic fluid. Heat from burning fuel or industrial waste is led in via the oil-filled circuit at a temperature of 250–300 °C to the heat exchanger, creating steam and super heating the organic silicon fluid.

Organic Rankine cycle (ORC) machines are used to convert low-temperature heat resources into power. Examples include systems making use of waste heat in a cogeneration system, low temperature geothermal electricity generation, solar ponds, and potentially OTEC.

The efficiency of current high temperature Organic Rankine Cycles does not exceed 24%. Typical steam Rankine cycles show a thermal efficiency higher than 30%, but with a more complex cycle design (in terms of number of components or size).