Heat to Power Technology
Organic Rankine Cycle
What is an Organic Rankine Cycle (ORC)?
Organic Rankine Cycle (ORC) systems convert heat to electricity. Regardless of the heat source, no new emissions are generated in the heat to power process, making the resulting energy emission-free.
To date, there are more than 565 ORC plants worldwide, generating a total of 2.75 gigawatts of electricity.
ORC systems are the most mature and widely deployed low-grade heat to power solutions. ORCs employs the same basic principles as steam-powered turbines, in that a fluid is cyclically heated, expanded through a turbine, then cooled.
However, there is one significant difference. Instead of water, ORC technology uses an organic fluid with a lower boiling point, making ORC systems the perfect choice for heat to power projects between 120°C and 450°C (248° and 842°F) in any location.
Yes, even in cold climates and snowy conditions.
ORC Waste Heat Recovery
This low to moderate temperature range matches that of the waste heat streams of many industrial processes. Organic Rankine Cycle technology taps into that waste heat and turns it into useable energy through the following steps:
The waste heat is extracted and diverted to the ORC system.
The heat is transferred to the organic working fluid.
The organic working fluid vaporizes.
The vaporized organic working fluid passes through the turbine.
The vapor expands, driving the turbine and generating electricity.
The vapor travels to an air-cooled condenser, where it returns to a fluid state.
The fluid is pumped back through into the system for re-use.
Energy production from low-temperature sources like waste heat can be made from efficient through Organic Rankine Cycle (ORC) heat recovery.
ORC Technology Components
Although ORC technology operates at lower temperatures and pressures than steam turbines, the components of ORC systems are not very different. Most ORC systems include:
A turbine — the key element for ORC systems, the turbine is pushed by the expanding fluid and rotates the turbine shaft of the generator (which in turn, converts the mechanical energy of the turbine to electrical energy)
Heat exchangers — extract thermal energy from the waste heat source and transfer it to the working fluid
A condenser — uses air, eliminating the need for water to cool the working fluid
A feed pump — pressurizes the working fluid and moves it through the ORC system
The components work together to achieve the greatest power output possible.
ORC power plant
(Diagram: Exergy International)
View an animated version of the ORC process here.
Organic Rankine Cycle Advantages
One of the main Organic Rankine Cycle advantages is delivering heat recovery solutions at temperatures that don't work as well with steam turbines. Other benefits of ORC technology include:
Compact and automated — allows for simpler and lower-cost maintenance
Modular configuration — enables ease of transportation and installation
Design flexibility — allows for the use of the organic working fluid that makes the most sense
The fact that the Organic Rankine Cycle uses organic fluids rather than water provides another unique advantage. Unlike water, the organic fluids don't corrode the turbine and other components, leading to longer system life.
Using Organic Rankine Cycle With Other Heat Recovery Sources
Using the Organic Rankine Cycle for heat recovery from industrial processes is an effective way to produce baseload, emission-free energy and lower your carbon footprint. Since they convert thermal energy at low temperatures to electricity, ORC systems are suitable for numerous industries, like oil and gas, geothermal energy, manufacturing, and forestry, with plant sizes ranging from 100 kWe to 50 MWe.
Learn More About Organic Rankine Cycle (ORC) Technology From Terrapin Geothermics
Terrapin Geothermics is leading the way in North America with heat conversion projects that deploy ORC technology. We're uniquely positioned to help you get the most out of an Organic Rankine Cycle system. Contact us today to put our expertise to work for you.