Last week, Stadtwerke Gießen AG (SWG) laid an important foundation stone for the future operation of the second wood-fired heating plant in Gießen. The former coal-fired heating plant in Marshall Village, between Grünberger Strasse and Rödgener Strasse, has been out of operation since 1988 and is now being converted. The use of wood as a fuel will reduce CO2 emissions by over 3,700 tonnes per year compared to fossil fuels.
For Stadtwerke, the building and the existing pipework system represent an ideal location for a new wood-fired heating plant. Last week, the Dillenburg-based company Weiss delivered a new boiler with a nominal heat output of 2,100 kilowatts. Previously, the Marshall Village housing estate was supplied with heat from the US Depot CHP plant.
The heat supply had to be interrupted for necessary maintenance work on the supply systems. When the new heating plant goes into operation on schedule in May, this area can be operated both in conjunction with other heating plants and as a stand-alone solution, providing sufficient heat.
This is not the first wood chip plant in Giessen - the municipal utilities commissioned the first wood-fired heating plant back in January 2002. The prototype is located on the site of the US depot.
The wood in the form of wood chips is transported into the combustion muffle of the boiler by means of a screw conveyor and a scraper chain conveyor. The fuel and air supply are controlled by a computer depending on the heat output and the flue gas analysis, which is linked to remote monitoring at the municipal utility's network control centre. The boiler has the advantage that both moist wood (from the forest) and dry wood (from panels, for example) can be burnt.
When the second heating plant goes into operation this year, wood will account for 3 per cent of the fuel used by the municipal utilities.