Organic Rankine Cycle – ORC

What is Organic Rankine Cycle?

What is Organic Rankine Cycle?

The Organic Rankine Cycle (ORC) is an evolving energy system for power production utilizing geothermal resources and recovered waste-heat.

While the Rankine Cycle utilizes thermal heat to convert water to steam, which expands through a turbine (screw or other expander) in order to generate electricity, the Organic Rankine Cycle (ORC) uses an organic fluid (instead of water) that has a much lower boiling point, thus capable of utilizing heat from sources with lower temperatures. The fluids that are commonly used are refrigerants and hydrocarbons (Butane, Pentane and their derivatives) that have lower boiling temperature than water.

The ORC can aid the achievement of the carbon footprint reduction targets of many industrial processes (waste heat recovery, biomass). The ORC enables the use of low, medium and high enthalpy flows from renewable sources (solar, geothermal, etc.) to be utilized in thermodynamic cycles based on Rankine architecture.


Organic Rankine Cycle in Recovered Energy Generation

Waste heat recovery is one of the most important development fields for the Organic Rankine Cycle (ORC). It can be applied to heat and power plants (cogeneration plant), industrial and farming processes (such as organic products fermentation, hot exhausts from ovens or furnaces, lime and cement kilns), flue-gas condensation, exhaust gases from gas turbines (compressor stations), condenser of a power cycle, etc.


Recovered Energy Generation ORC 


Organic Rankine Cycle in Geothermal energy power plant

Geothermic heat sources vary in temperature from 50 to 350°C. The ORC is therefore perfectly adapted for this kind of application. Air cooled ORCs operate on a closed loop, do not consume any water and are therefore free of the environmental consequences that accompany water based systems. Air-cooled condenser technology enables us to re-inject almost 100% of all extracted geothermal fluids, thereby avoiding the use of geothermal steam condensate or external water resources for cooling and preventing the need for chemical additives. The 100% re-injection also sustains reservoir life and productivity.


Geothermal Organic Rankine Cycle


Ormat offers unique renewable power solutions based on the ORMAT® Energy Converter (OEC), a power generation unit which converts low, medium and high temperature heat into electrical energy. With 77 US patents (and 9 patents pending), the OEC is a state-of-the-art implementation of the Organic Rankine Cycle (ORC) technology that we have refined and perfected through more than 30 years of use under the most challenging conditions.