Waste heat to power

ORC Technology Overview

An Organic Rankine Cycle (ORC) unit is a power generation system which uses heat as its energy input and converts this heat to electricity. The system is similar to a conventional Rankine cycle (i.e. a steam turbine based system), with the key difference being that the steam is replaced with an organic working fluid. The efficiency of an ORC system is very similar to a conventional Rankine Cycle system, with approx. 20 – 25% of the available heat converted to electricity.

A wide variety of heat sources can be used to drive an ORC system, with typical applications including biomass combustion, geothermal energy and waste heat from industrial processes.

One of the most common applications of ORC is the recovery of heat from the exhaust stream of open cycle gas turbines. The thermal energy contained in the exhaust gas is captured using an exhaust gas heat exchanger and delivered to the ORC, with little or no impact on the turbine operation. This can increase the efficiency of the system by over 30%.

ORC Schematic - CES Logo

CES Energy offers turnkey ORC systems in the range 1 MWe to 20 MWe. CES can deliver ORC systems under BOO and BOT contract models, financing the installation and selling the power generated to the client under a long term Power Purchase Agreement (PPA). By partnering with world leading suppliers and manufacturers, CES Energy provides the highest level of system availability and performance.


The main benefits of ORC technology include:

Significant reduction in oil/fuel consumption: e.g. for a gas turbine, system efficiency can be increased by over 30%, which leads to a corresponding reduction in fuel consumption.

Long Term operation with extremely high availability: Due to the low temperatures and pressures involved, and the low stress on the system, ORC systems have extremely long life (>20 years) and high availability. Typical availabilities are > 98%.

Little or no impact on process: Regardless of the heat source, an ORC unit has practically zero impact on the process. For a gas turbine system, the turbine’s capacity will be retained, and any ORC downtime will not impact the turbine operation.

ORC does not need to be positioned close to the heat source: The ORC can be placed at some distance from the heat source, with heat transferred via an efficient thermal oil circuit.

Operation is fully automatic with minimal maintenance required: ORC systems are extremely low maintenance, and do not require specialised personnel for operation. Even in remote locations, the system can operate unmanned for long periods, remotely monitored by CES Energy.