The Organic Rankine Cycle's principle is based on a turbogenerator working as a conventional steam turbine to transform thermal energy into mechanical energy and finally into electric energy through an electrical generator.

The organic Rankine cycle (ORC) is one of the feasible technologies to recover waste heat from low to medium temperature heat sources and to generate electricity.

The fluids are alkanes, fluorinated alkanes, ethers and fluorinated ethers. The ORC cycles operate between 100 and 30 °C typical for geothermal power plants at pressures mostly limited to 20 bar, but in some cases supercritical pressures are also considered.

An organic Rankine cycle (ORC), is fundamentally the same as a steam Rankine cycle; however, it uses a lower boiling point organic fluid to better match its operation to lower temperature heat sources. ORC systems can achieve better efficiencies than steam turbines for smaller systems (less than a few MW_e).