District Heating

District heating – energy with a future

District heating not only reduces the need for resources – it also protects the climate. With an average annual district heating production of over three billion kilowatt hours, EnBW is one of the largest district heating companies in Germany.

In such transport pipes with an inside diameter of up to 70 centimetres, the hot water is transported at temperatures of between 80 and 130°C.

District heating – how does it work?

Simplified representation of an integrated district heating supply system

District heating systems are supply systems consisting of district heating plants, plants for maintaining pressure and volume, water treatment, district heating transport, and distribution networks, as well as customer transfer stations. Because such a system must always be in equilibrium between district heating output and generation, an additional heating centre is responsible for the efficient control of the system.

District heating is therefore a valuable product that is predominantly produced by combined heat and power generation (i.e. the joint generation of electricity and heat). And the district heating supply is as simple as this: The district heating is transported to the customer via a pipeline system using a transport medium (usually hot water). The heat is transferred to the building in the house transfer station. The cooled water is then returned from the respective building to the network.

Functionality of the co-generation of heat and power

The combined generation of electricity and heat (co-generation of heat and power) is a technology with which the energy is used far more effectively than in the case of separate electricity and heat generation. There is also a correspondingly reduced impact on the environment.

First of all, everything functions in the same way as a regular power station that supplies electricity exclusively: In the boiler, steam is generated by combustion, which drives the turbines and thus produces electricity. However, this is followed by a further step: The hot steam is reused – this time to generate heat, which reaches the customer via well insulated pipelines. The “transport medium” is either water or hot steam.

As far as fuels are concerned, district heating plants are very flexible. Coal, natural gas, heating oil, waste, biomass – everything is possible. This means that renewable energy sources can also be used without any problems. A real plus for conurbations in which regenerative resources – such as solar collectors – can otherwise only be used to a limited extent for space reasons.

Currently, more than 80% of district heating in Germany is generated by combined heat and power generation – in the Stuttgart region, this is over 90%. The energy savings compared to the separate generation of electricity and heat are between 30 and 50%. This makes ecological and economic sense.

Simplified representation of an integrated district heating supply system

Functionality of the co-generation of heat and power

Construction of a district heating system, using the example of the Mittlerer Neckar district heating network

District heating is based on a highly complex supply system which, in addition to kilometre-long pipes, also includes co-generation plants, distribution points, transfer stations, and shaft structures.

About 90 % of the district heating is generated by combined heat and power generation at the Stuttgart-Münster, Stuttgart-Gaisburg, and Altbach/Deizisau power plants, as well as the Marienstraße peak heating plant. Fuels such as hard coal, waste, and natural gas are used.

The system support of the district heating supply, which consists of volume and pressure maintenance facilities, the circulation of the district heating water, and the maintenance of the required water quality, takes place at the three CHP plant sites.

A total of eight substations with pressure boosting stations are operated in the network of the Mittlerer Neckar district heating network. The substations serve to increase the pressure, as well as to mix and distribute the district heat to the hydraulically separated sub-networks.

The network covers approx. 260 km and is one of the largest in Germany. The hot water in the pipes reaches temperatures between 80 and 130°C. For safe operation, additional 1,700 shaft structures are required in the Stuttgart city area.

The region’s network is controlled from the central heat control station in the Stuttgart-Münster combined heat and power plant. This is where production and feed-in, as well as transport and distribution, are monitored. The 24-hour fault hotline is also located here.

In the Mittlerer Neckar region, some 7,800 transfer stations are used to supply customers. Whether a small house connection or a large transfer station for industrial applications – flow rate, temperature, and pressure are controlled here.

The approximately 300 employees at the generation sites, in the network, and in the head office, are responsible for the smooth operation of district heating, plant maintenance, and control of district heating activities in the Mittlerer Neckar District Heating Network.

Frequently asked questions

Why is district heating environmentally friendly?

The savings that can be achieved thanks to district heating are enormous: On one hand, the utilisation rate of the power plants will increase to more than 80%. On the other hand, much energy that would otherwise be required for the separate generation of heat in individual heating systems is saved. Overall, district heating from combined heat and power generation can reduce primary energy consumption by up to 40 % compared with separate electricity/heat generation. The consequences: Fewer resources required and fewer harmful greenhouse gases emitted. The amount of pollutants also decreases. This is because the modern systems of our combined heat and power plants clean the exhaust gases much better than is possible with thousands of individual fireplaces.

What are the advantages of district heating over gas heating?

District heating offers a very high security of supply. EnBW’s excellent distribution network guarantees a reliable supply – even in cold winter months.
A connection to the district heating network is cheaper than the purchase of a gas or oil heating system. An approval procedure for the heating system is not necessary. As a rule, the insurance premiums for household insurance are more favourable. Compared to your own heating system, district heating systems also require considerably less space, because, for example, no chimney and no surfaces are required for a tank and the boiler. Wall mounting is also possible. The installation room does not require sound insulation.
The operating and maintenance costs are low because the customer uses components that are less susceptible to faults when supplying district heating. Expenses for chimney cleaning and compliance with safety regulations (e.g. for the tank and the burner) are eliminated. The district heating supplier is responsible for generating and transporting the energy. In general, district heating systems are less susceptible to faults than boiler systems.
Because no open or closed fireplaces are required for the district heating system, there is no possibility of an explosion or the danger of a domestic fire caused by exploding pipes or tanks.
For connection work and ongoing operation, we are personally on site for you. As a regional and personal contact, we offer you peace of mind even in the event of disruptions – day and night.

How can I check whether my home or business is located in the district heating area?

Would you also like to benefit from the advantages of district heating? Simply check whether your house or business is located in one of these areas and then contact us: Your EnBW customer advisor will answer all your questions on +49 (0)711 289-47860.

Further information can be found here.