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 long and expansive experience in the fields of energy generation and district heating.

The project was then triggered by the need to renovate a police station. Its old heating installation ran on oil and coal and had to be replaced. 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 creation was then completed by the search for a suitable location for the plant, by 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.

The project details

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 is running throughout the year. Secondly, the hot water boiler is powered by wood chips and has a thermal capacity of 2 MWth. It is running from October to March / April as a medium load, and completes the hot water production from the CHP unit during winter times. 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 maximal heating demand amounts to 8 MWth, and the network distributes about 14,200 MWh per year to the customers.

Biogas and biomass

Foto: Peter Sierigk

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 biogas production sites located everywhere in Germany, and is produced through fermentation of renewable raw materials and waste from the agriculture and breeding farms. According to this supply circuit and “extraction” means, the produced energy can be considered as fully renewable.

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 answers alone to the needs of 375 households. The wood boiler is own 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 the forests, municipal landscaping and neighbouring mountains. So, apart from using renewable materials, this boiler runs on waste that would otherwise be lost.

Since the plant is inside an urban area, aspects such as trucks traffic had to be tackled. For the wood supply, the deliveries by truck occur by an average of once to twice a week. The frequency of delivery is higher in winter, when the need for heat is greater. In summer there is no delivery since the boiler is not in operation. Altogether there is only a minor increase in the delivery traffic, with little disturbances for the district.

Key achievements

• The heat and power installation produces 9,200 MWh per year of 100% green electricity and 15,600 MWh per year of 98% green heat.
• 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.
• The use of different fuels, as well as the thermal storage allows the system to be flexible to fuel prices and to daily fluctuations.

 

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