EXERGY design, manufacture, supply and operate Organic Rankine Cycle(ORC) systems for geothermal, waste heat recovery, biomass and solar (CSP) applications.

Organic Rankine Cycle (ORC) systems are a solution for power production from low to medium temperature heat sources in the range of 80 to 350 °C. This technology allows for exploitation of low-grade heat that otherwise would be wasted. ORC can also be an ideal solution when the size of the application is too small for a steam power plant.

The working principle of an Organic Rankine Cycle power plant is similar to the most widely used process for power generation, the Clausius Rankine Cycle. The main difference is the use of organic substances instead of water or steam as working fluid. The organic working fluid has a lower boiling point and a higher vapour pressure than water and is thus able to use low temperature heat sources to produce electricity. The fluid is chosen to best fit the heat source according to their differing thermodynamic properties, thus obtaining higher efficiencies.

All existing ORC cycles worldwide have been based on turbomachinery employing axial or radial inflow turbines. Exergy has introduced the new alternative configuration of the Radial Outflow Turbine (ROT) and is unique in having this extremely efficient technology.

Take a look inside the operation of an Organic Rankine Cycle process

ORC Process

The advantages of the ORC over the traditional Rankine cycle include:

  • Suitable for lower temperature applications
  • Low rotation and tip speed, together with the absence of a liquid
  • Phase during expansion lead to a reliable and long lasting expander, with far simpler and lower cost maintenance than with a steam turbine
  • Compact and automated, meaning no need for operators
  • Ideal for cycling environments and where fast start stops are required
  • Modular configuration for ease of transportation and installation
  • Design flexibility with the option to utilize the most efficient working fluid available
  • Operational flexibility for superior off-design performances
  • A no-water consumption option is possible
  • High market availability of chemicals /fluids with refilling rarely required
  • Low associated costs for foundation and assembly
  • Simple and reliable system maintenance makes for long product life

By converting thermal energy to electricity at low temperature the ORC provides crucial green technology to improve energy efficiency of new and existing applications. ORC is suitable for a wide range of applications, of sizes between 100kW and 50MW including:

  • Low enthalpy geothermal sources exploitation (90-260˚C)
  • Heat recovery from:
  • Industrial processes (e.g. steel mills, glass mills, furnaces etc.)
  • Power generation (e.g. biogas, diesel, gas engines)
  • Gas compression stations
  • Biomass plants
  • Concentrated Solar Power (CSP)