Temperature resistant geomembrane for heat storage pit

More efficient energy use by long-term heat storage pit.

Construction Building

Project name: Long-term heat storage pit
Project date: October 2013
Products: High Temperature Resistant (HTR HDPE) geomembrane 2.5 mm thickness


The company solarcomplex AG operates a district heating system in Emmingen (Germany). Heat is generated
by 4 power stations. In 2013 it was decided to implement a long-term heat storage pit into the system. It will be operated with temperatures between 55°C and 95°C and will have a heat capacity of 46 MWh. Upon completion, the heat storage pit is expected to significantly reduce the operating cost due to a more efficient use of heat. Calculations show that each year the equivalent of 27 000l of oil can be saved.

District heating system Emmingen

Heat storage pit

The heat storage pit consists of a 1000 m³ big reinforced concrete water tank, which is used to store the energy. The bottom, the walls and the lid of the storage pit are heavily insulated to minimize heat loss. A 2.5 mm thick AGRU High Temperature Resistant (HTR-PE) geomembrane was installed on the inside of the tank. All joints are welded and the membrane ensures an absolute leak proof lining.

Heat storage in Emmingen

High temperature resistant geomembranes (Cupasol)

The HTR-PE geomembranes have been developed by AGRU during the last few years. This process was supported by participation in various research projects. High temperature resistand geomambranes are welded and installed like traditional geomembranes and provide the same level of performance properties. Additionally they offer outstanding long-term performance at elevated temperatures. The compound used was tested according to ISO 9080 and complies with DIN 16833 (PE-RT). Thus excellent long-term strength and temperature resistance are confirmed.

PE-RT Geomembrane


Due to the improved life time at elevated temperatures, HTR geomembranes can provide long-needed solutions for industries and applications where higher temperatures are needed. Possible applications include (but are not limited) to the following:

  • Power generation facilities (solar thermal, biomass, geothermal, ...)
  • Hot water storage
  • Industrial waste water and process water
  • Bioreactor landfills
  • Oil and gas industries
  • Mining operations and heap leach facilities

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