The ORC turbogenerator uses medium-to-high-temperature thermal oil to preheat and vaporize a suitable organic working fluid in the evaporator (4>5). The organic fluid vapor rotates the turbine (5>6), which is directly coupled to the electric generator, resulting in clean, reliable electric power.

The Rankine cycle is an ideal thermodynamic cycle involving a constant pressure heat engine which converts heat into mechanical work. The heat is supplied externally in this cycle in a closed loop, which uses either water or any other organic fluids (Pentane or Toluene) as a working fluid.

The low speed ORC process has an electricity output of 400–1100 kW and electricity to heat ratio of 0.18–0.22. The ORC-concept has two circuits, one for thermal oil and another for organic fluid.

Solar thermal power The organic Rankine cycle can be used in the solar parabolic trough technology in place of the usual steam Rankine cycle. The ORC allows electricity generation at lower capacities and lower collector temperature, and hence the possibility for low-cost, small scale decentralized CSP units.