Thermal energy storage
Technical energy storage is the decisive prerequisite for future comprehensive use of regenerative energies. Since the energy offer from nature does, however, only rarely correspond to the demand profile of the users, energy storage can essentially contribute to balancing out the natural fluctuations of a renewable energy offer. This makes it possible to achieve systematic disconnection of the energy demand from the energy offer.
Thermal energy storage is outstandingly suitable for use of previously unused exhaust heat (from production or IT-applications) as an energy source for heat supply. This saves fossil fuels in other locations and increases the primary energy efficiency as a whole.
Thermal energy storage is useful
- To bridge the time difference between heat generation and heat use
- To compensate for load peaks
- To store exhaust heat from production processes or refrigeration plants
- For use of renewable energies and substitution of fossil fuels
- To avoid CO2-emissions
Seasonal energy storage
Energy storage systems are recommended if the annual energy profile of an energy concept has time segments with an excess of exhaust heat from cooling and phases with a net heat demand in the heating period. The thermal storage capacity of the energy storage can close the demand gaps. In many cases, fossil fuels are not needed at all.
Seasonal storages are either designed as earth storages (geothermal), water storages or latent-energy storages (ice banks).
Typical applications of thermal energy storages
- Storing condenser heat from commercial refrigeration systems as power source for delayed heating demand
- Supply of production processes, test benches, machine and tool cooling with cooling energy with seasonal utilisation as a heat source for covering the heating demand
- Smoothing the peak load demands
- Ensuring redundancies
- Storage of solar heat as power source for heating demand in winter
- Geothermal energy (earth storage) as heat source for seasonal heating demand and heat sink for covering the cooling demand
Ice banks or latent-heat accumulators use the melting heat of water and have a high energy density in the phase change (solid/liquid). They are particularly suitable for efficient storage of thermal energy in the low temperature range.
Latent-energy storage: Efficient storage of thermal energy
Large energy storage systems are usually produced in nearly any size of water-impermeable concrete and are often installed under the terrain surface. Concrete water storage tanks to supply extinguishing water may be used as thermal accumulators within the temperature range of +5 °C to +40 °C.
Hafner-Muschler cooperates with special concrete container construction companies or provides contact information for experienced specialist companies.
Latent-energy storage systems essentially are built the same as water storage tanks
Thermal use takes place via an additional internal heat transfer medium. If heat is withdrawn up below the 0 °C-border, the aggregate condition of the stored water switches from liquid to ice. The heat carrier medium within the heat exchanger is cooled in the HM heat pump until an ice jacket slowly forms at the top of the heat transfer tube, which will spread slowly to the defined limit if more heat is withdrawn. The stored ice volume serves as a heat sink for cooling purposes if necessary.
HM has developed a special geometry for the heat transfer media made of spiralled plastic tubes with an extremely large surface. This keeps the temperature difference between the transport medium and the storage temperature as low as possible, which in turn is very important for efficiency of the heat pump. HM has in-house calculation competence for designing the optimal accumulator size and internal heat transfer media.
Heat pumps of the series "HM:WP-hybrid" and HM cooling-heating-composite systems are ideal combinations for the energy storage. The integrated MSR-technology contains the required circulation pumps and the freely programmed source-sink management for automated operation of an energy storage system.