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Stadtwerke Bielefeld GmbH

Overall planning

Bielefeld, Germany

Operational since 12/2010

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The plant

For over 150 years, the “Stadtwerke Bielefeld” have been providing comprehensive utility services, including electricity, gas, water, and district heating. In April 2008, the “Stadtwerke Bielefeld” introduced a new ecological energy concept. The existing coal-fired boilers of the “Stadtwerke Bielefeld” were decommissioned in 2012 due to age. As a result, a new biomass cogeneration plant based on wood chips was constructed at the “Schildescher Straße” site to ensure future heat supply. The generated heat is fully fed into the district heating network as base load supply. The generated electricity is fed into the public grid and compensated according to the Renewable Energy Sources Act (EEG). To construct the power plant at the “Stadtwerke Bielefeld” site, the first step involved demolishing a cooling tower of the existing facility to make room for the new building. The facility was built in the midst of the “Stadtwerke Bielefeld” premises in a very limited space. The operation of the facility saves 17.000 tons of carbon dioxide annually.

The technology

Untreated forest residual wood and landscape maintenance material are used as fuels in the facility. The wood is transported to a grate combustion system using a push floor. Additionally, a covered storage area has been built to hold a fuel supply for 3 to 4 days. The resulting hot flue gases from the combustion process are directed through an adjacent heat exchanger, where the thermal oil is heated to a temperature of approximately 320 °C. The hot thermal oil is then transferred as a heat transfer medium to the silicone circuit of the ORC module, where the silicone oil vaporizes and drives a turbine with a generator. The generated electricity is fed into the public grid. The flue gases produced during combustion are cleaned through a cyclone separator and electrostatic precipitator, and then released into the atmosphere through a 35-meter-high chimney.

Technical data

Fuel

untreated forest residual wood, landscape maintenance wood

Fuel quantity

25.000 t/a

Firing

Combustion heat capacity

8.400 kW

Electrical power

1.300 kW

ORC Condenser

Heat output

5.800 kW

Flue gas dedusting

using an electrostatic precipitator