Combined Heat & Power

Combined heat and power, otherwise known as cogeneration, is the simultaneous production in the same plant of thermal energy (heat) and mechanical energy.

The thermal energy is used to provide heating and hot water over a network and by using an alternator, the mechanical energy is transformed into electrical energy, which can be consumed or sold to an electricity distributor.

What is generally involved in a cogeneration (combined heat and power) unit?

A cogeneration unit typically consists of a primary driver in which fuel is converted into motion and heat, a generator to transform the motion into electricity, and a heat recovery system to collect the produced heat.

The thermal energy released by combustion when electricity is produced, which is usually lost (and is known as ‘free energy’) is thus captured and used through cogeneration. The mechanical energy is generally transformed into electricity by coupling it with an alternator; it is then sold to the network and/or consumed on the production site. This technical principle can be adapted to a wide variety of energy production installations, especially heating systems connected to collective heating networks and industrial installations, which simultaneously satisfy different energy needs on the same site. One installation can thereby supply electricity for local needs and heat, which can be used for heating or industrial processes.

In addition to gas engine, gas turbine and steam turbine cogeneration, two other technologies can be used:

  • The combined cycle: widely used, and it combines two of the mentioned techniques, in series, to increase the overall energy yield
  • Trigeneration: working in the same way as cogeneration, but supplying complementary cooling energy from the thermal energy produced (cold by absorption).

What are the advantages of a combined heat and power unit?

The main advantages of a combined heat and power unit are:

  • High overall efficiency
  • Co-generated electricity reduces heating prices
  • Reductions in CO2 emissions per kWh
  • Decentralised power generation
  • Various oxidizing agents can be used.

Want to learn more about Veolia’s cogeneration (combined heat and power) solutions?

In Australia

In New Zealand