Thermal heat from pit water: The Ruhr valley provides heat

The Ruhr Valley: old shafts and mines. But what happens to them if they are not being marketed as industrial monuments just yet? Previously, old shafts incurred costs because they have always presented a threat to the drinking water supply. The old Arnold mining shaft at the Robert Müser mine in Bochum is now being used as a source of heat within the context of a pilot project.

As with every shaft that has been shut down, the pit water must be pumped out in order to prevent an uncontrolled increase in the water level and the associated pollution of drinking water. Yet the pit water can still be useful. How? Stadtwerke Bochum (municipal utilities company) together with RAG have found this out. Within the context of a pilot project, the Bochum pit water is now used as a source of heat.

Engine for progress:

  • an innovative concept
  • fuel requirement reduced by 35 %
  • the potential to provide 5,000-10,000 households with heat
  • transferability

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Photo: Stadtwerke Bochum

The 20°C pit water is pumped up from the Robert Müser shaft in Bochum and used to provide thermal heat for four existing buildings nearby: an elementary school, a canteen, a swimming pool on the grounds of a school and a fire station.

35 per cent heat coverage using pit water

At the Robert Müser mine, pit water is pumped upwards. This pit water has an average temperature of around 20 degrees centigrade. The heat from the pit water is decoupled and distributed via a local heating network to existing buildings nearby and brought up to a higher temperature level with the help of heat pumps. In this way, approximately 35 per cent of the building's heat consumption is to be covered and about 1,200 MWh and 245 tonnes of carbon dioxide emissions are to be saved per year. The remaining 65 per cent of heat consumption is provided using conventional gas boilers already in place. The pilot project has been running for two years.

Innovative use of the available infrastructure

Because the water contains many dissolved substances, such as corrosive salts for example, different alternatives had to be tested with respect to technical feasibility, economic viability and transferability, in order to be able to use the pit water per heat exchanger. With the result that two separate water cycles are used: a cold and a warm local heating network. In order to supply the buildings, the low temperature heat at about 20 degrees is heated up to 60 degrees centigrade by a heat pump in the building, depending on requirements.

Great potential

In the project, a new concept was developed, tested and optimised to heat existing buildings. The results and experience gained are now being prepared and will serve as a base for similar projects. RAG estimates that heat for about 5,000 to 10,000 households could be provided by pit water from shafts in the Ruhr Valley.

Partners and sponsors

  • Stadtwerk Bochum Holding GmbH
  • RAG Montan
  • Bundesministerium für Wirtschaft und Energie (BMWi)