The “Hungerkamp” project is an innovative initiative in the city of Braunschweig in Germany. Its origins are rooted in the energy provider’s ambition to contribute to climate protection and its experience in the fields of energy generation and district heating. The project was triggered by the need to renovate a police station’s heating installation that ran on oil and coal. The project leaders decided to use this opportunity to go beyond the mere replacement of the heating plant and to develop a project of green and local heating network in the neighbourhood. The meeting with a wood trader further helped to work out the concept of the system. The project’s creation was then completed with the search for a suitable location for the plant, winning other potential customers and the signature of long-term contracts for heat delivery.  The project won an award at the 2015 Global District Energy Climate Awards.

Foto: Peter Sierigk

The heating and power station is composed of four main components. The CHP unit powered by biogas, has an electric capacity of 1,19 MWel and a thermal capacity of 1,16 MWth. It produces heat as a base load and runs throughout the year. Secondly, the hot water boiler is powered by wood chips and has a thermal capacity of 2 MWth. It runs from October to March / April as a medium load, and completes the hot water production from the CHP unit during the winter time. The third element is a 6,5 MWth hot water boiler powered by natural gas. It is used for the peak load and as a reserve. The last component is the hot water storage, composed of two 50 m³ tanks, which enables to balance supply and demand. The local heating network is 4 km long and distributes hot water for heating purposes to 32 customers. The maximum heating demand amounts to 8 MWth, and the network distributes about 14.200 MWh per year to the customers.

The biogas cogeneration unit is supplied by a pipeline connected to a network and consumes yearly 2 million m³ of biogas. The biogas comes from production sites throughout Germany created by the fermentation of renewable raw materials and waste from the agriculture and breeding farms. The second component of the system is the wood boiler, to complete the heat generation. It produces 6.000 MWh of renewable warm water, and alone provides the needs of 375 households. The wood boiler is owned and operated by the fuel trader who acts as business partner. The produced heat is then sold to the energy provider and injected on the heat network. It consumes 1.600 tonnes per year of residual forest wood and materials from landscape management, such as treetops and smaller branches. The wood mostly comes from the surrounding region: from forests, municipal landscaping and neighbouring mountains. So, apart from using renewable materials, this boiler runs on waste that would otherwise be lost.

The whole system replaces 34 old plants running on heating oil and coal and achieves 8.000 tonnes of CO₂-savings per year, thanks to the use of cogeneration and the replacement of fossil fuels by renewable raw materials.

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