Large heat storages

A sustainable heat supply combines various climate-neutral resources such as solar thermal, geothermal, environmental heat and industrial waste heat.

These are available in their characteristic courses throughout the day or the year.

Large heat storages collect the heat and pass it on to consumers at the right time.

Large heat storages as the key to the integrated system

A large heat storage is the module in a large heat supply system that connects all heat and electricity sources.

Depending on the size and function of the storage, different types – or even several – can be used:

• Seasonal heat storages, for example, store heat from solar thermal in summer and supply it to the heating network in winter.
• Buffer storages, for example, take up heat from waste heat sources and release it again after a few hours or days.
• Multifunctional heat storages are so large and flexible in comparison to heat consumption that they can store heat both in the short and long term and transfer it back to the heat supply as required. Multifunctional heat storages connect sectors and ensure the supply.

The integration of the storage into the overall system is particularly important for efficient and therefore economical operation.

Cost-effective construction methods

The larger the heat storages become, the more important cost-effective construction methods are. In order to save material, large multifunctional heat storages are partially or fully integrated into the ground and are therefore statically stabilized.

These construction methods as underground heat storages are state of the art and are continuously being further developed in research projects.

Leading the way in the development of large heat storages

Solites is a know-how leader for construction methods, component designs, system integration and possible applications of large heat storages.

We are currently working on the further development of construction methods, new materials and the economic integration of multifunctional heat storages into overall systems.
The aim is to develop storage technologies that meet the requirements of the district heating sector and achieve long lifetimes – in other words, multifunctional.

30 years of experience with large heat storages

Solites experts have been working in the field of large heat storages since 1995. The scientific and technical support of pilot projects for seasonal heat storages formed the basis for further research. The team developed projects, used simulations to work out the optimum system integration and dimensioning, accompanied the structural implementation and then measured the systems for several years, i.e. compared the actual temperatures, pressures and conditions in the storage facility with the simulations.

The German working group on long-term heat storages has been in existence since 1999 under the leadership of Dirk Mangold. The working group is now based at the district heating association AGFW and currently comprises around 50 participants from industry and science from Germany, Austria, Switzerland and Denmark.

Solites has been involved in an advisory capacity in the development of Danish underground heat storages since 2000. On behalf of the Danish Ministry of Energy, Solites has evaluated the operating data of the underground heat storages in Marstal, Dronninglund and Gram for the years 2014 to 2018. Since then, Solites has been a member of the Danish operator group for large heat storages, which meets once a year to share new findings and discuss operating experience.

Solites advises on the development of VDI guidelines. Thomas Schmidt is responsible for this in VDI 4640 – Sheet 3 (Thermal utilization of the underground – Underground thermal energy storage).