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).

Additionally, ORCs eliminate the need for full-time plant operators because they operate at lower pressures and do not need water chemistry maintenance. However, working fluid cost, decomposition, temperature limits are an organic Rankine cycle's primary disadvantages.

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.

A waste heat recovery cycle explained A waste heat recovery system extracts thermal power from the exhaust gas of the industrial plant to feed the ORC module via the intermediate fluid. This fluid, usually oil, pressurized water or steam, transfers heat to the organic fluid in the ORC evaporator, where it vaporizes.