Combined Heat and Power

For its autonomous generation of energy RheinEnergie has for decades utilised the simultaneous production of electricity and heat in just one plant – combined heat and power. Our combined heat and power plants are located in the centre of Cologne and in the city's various suburbs, e.g. Merheim, Merkenich and Niehl.

Only electrical energy is generated in conventional condensation power plants. Water is heated up, creating extremely hot steam whose high pressure drives a turbine connected to the generator. After completing its task in the turbine, the steam subsequently escapes into the environment as waste heat. In a combined heat and power plant the principle is different: The steam is not only generated to drive the turbine but also intended to heat the district heat water and processing water as well being used for production. This way, the applied fuel can be utilised in two ways.

Gas and steam turbine plant -
improved efficiency and environmental protection

An additional increase in efficiency can be achieved by gas and steam turbine plants; the most advanced generation technology which power plant manufacturers can currently offer. RheinEnergie utilises this process at two sites: In Merkenich and in our state-of-the-art combined heat and power plant Niehl II, commissioned in April 2005.

The heart of a gas and steam plant, such as in Niehl, is the gas turbine which compresses the combustion air and fuel (natural gas) just like a jet engine. The gas turbine drives a generator with a capacity of more than 260 megawatts. The exhaust gas with a temperature of 1400 degrees is not wasted, but accomplishes another important task. It heats up water in a "heat recovery boiler". The resulting steam drives a steam turbine which in turn drives an additional generator. This generates another 140 megawatts of electricity.

In order to produce district heat, the power generators draw off a part of the steam from the steam turbine and divert it to a heat exchanger. The hot steam then transfers its heat energy to the water in the district heat pipes.

Due to technical reasons only about 40% of the fuel used in modern electricity-generating power plants can actually be transformed into electrical energy. Approximately 60% of the energy is lost to the environment as waste heat. However, in a modern plant, such as Niehl II, 86% of the fuel is used. This new plant offers not only economic but also enormous environmental advantages compared with the old plant Niehl I: For example, the discharge of carbon dioxide has been reduced by nearly 30% - almost 200,000 tonnes a year.

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