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).

Rankine cycle is a heat engine comprised of four internally reversible processes. and reversible (isentropic), the pump and the turbine, the only energy interaction with surroundings is work. For the two isobaric heat exchange processes, the devices are passive and there is no work, only heat transfer.

A simple Rankine cycle is based on pressurizing water with a pump, heating the pressurized water beyond its boiling point to produce superheated steam in the boiler, expanding the steam through a steam turbine, cooling the residual steam to regenerate water, and returning the water to the pump to start through the ...

An Organic Rankine Cycle (ORC) system is a closed thermodynamic cycle used for power production from low to medium-high temperature heat sources ranging from 80 to 400°C and for small-medium applications at any temperature level.