ORC E-Rational TECHNOLOGY & units


E-Rational ORC-1000

E-rational ORC 1000 series


  • 55 kWe
  • 70 kWe
  • 90 kWe
  • 110 kWe
  • 132 kWe


E-Rational ORC-4000

E-Rational ORC-4000 series


  • 250 kWe
  • 315 kWe
  • 370 kWe
  • 400 kWe
  • 450 kWe
  • 500 kWe



BEP Europe NV combines traditional components with patented expander technology to create electricity from waste heat. The E-Rational operates in a closed-loop Organic Rankine Cycle (ORC). Similar to a conventional steam engine that boils water into steam to produce mechanical work, an ORC uses low grade heat to boil a working fluid into a gas.


The E-Rational works on the principle of ORC (Organic Rankine Cycle) for the utilization of waste heat which is converted into electric energy. The E-Rational unit by the BEP company produces fuel-free and emission-free electricity from the process heat and waste heat starting at 85 °C. The E-Rational consists of a proven, patent-protected rotary expander. The E-Rational produces electricity, which is transformed from a source of low-temperature waste heat and offers a very attractive return of investment.

Working principle of E-RATIONAL

The system of converting heat into electricity using the E-Rational works on the principles of a closed Organic Rankine Cycle (ORC). The principle is similar to a conventional steam engine, where boiling water is converted into steam, which is then transformed into mechanical energy. The E-Rational uses unnecessary heat for heating-up the operating fluid to its boiling point and converts it into gas.

Steps in the process:

  1. Heat is passed through the evaporator into the working fluid, heats the working fluid to boiling point and converts it into steam.
  2. Steam enters into expander, which converts steam energy into mechanical energy.
  3. Steam is further cooled by using a source of cold water in the condenser and condenses back into a liquid state.
  4. The working fluid is pumped back into the evaporator. Then the cycle is repeated.

Schematic diagram of the principle of the E-Rational function

Schematic diagram

Patented Screw Expander

The patented "screw expander" offers significant advantages

  • Screw expanderAs a medium is used either hot water, thermal oil or low pressure steam
  • High system efficiency at very low rotational speed < 3500 rpm
  • Lubricating system is contained within the working fluid and no traditional lubricating system is needed
  • Low-speed operation
  • No gearbox or oil pump
  • Competitive cost
  • Simple and robust design
  • Proven technology more than 15 years


  • technical advantagesAs a medium is used either hot water, thermal oil or low pressure steam
  • Modular and scalable design (outdoor version)
  • Automated system of control and inspection
  • Easy integration into the hydraulic circuit of warm (hot) water CHP
  • Simple installation (max. 4 days to launch)
  • Contains only three main components with moving parts
  • Cooling by the use of air or water
  • Production of electrical energy without a combustion process
  • No toxic combustion products
  • Remote control and monitoring
  • Automatic Start / Stop systém

The E-Rational ORC transforms between 6–18% of low-temperature thermal energy, depending on the condensing temperature, to electricity.