Deutsche Version  ACT
Thermal Storage
Latent heat storage 12.4.2017

The fridge chosen for the storage integration. A fridge with bottom freezer and a capacity of 255/86 Liter.
© BSH Hausgeräte GmbH

Fridges with latent heat storage

Researchers are studying the economic and technical potential of

refrigerators with phase change materials as a sliding load in the

electrical network. The aim is to demonstrate the feasibility and

advantages and to determine the costs.

Project status Technical and economic study, investigation of integration concepts for the thermal storage in the fridge
Components for charching and discharching Heat exchanger
Temperature type Cold
Storage/Charging direct
Storage time short (hours to days)
Number of cycles 250 - 350 cycles/a
Charging temperature -30/-20 °C
Discharge temperature -25 /-18 °C
Storage capacity 3.200 kJ
Project duration April 2014 until March 2018

The project aim is to demonstrate the advantages of thermal storages as dispatchable loads compared to electrical storages.  During  the project the technical and economic potential of fridges with latent heat storage as dispatchable load in electrical grids will be evaluated. The latent heat storage will be integrated in a fridge with high market penetration, and will be tested under real life conditions in a demonstrator.

  • Part crystallized phase change material. © ZAE Bayern
  • The fridge chosen for the storage integration. A fridge with bottom freezer and a capacity of 255/86 Liter. © BSH Hausgeräte GmbH

The increasing numbers of fluctuating, renewable energy in the electrical grid will lead to situations were in part load of the grid the feeding of the renewables have to be limited on the one hand, and on the other hand there will be a need of reserve capacities for conditions with a high load and weak feeding of the renewables. This will lead to bad utilization ratio for the reserve capacities and high specific costs per supplied Kilowatt-hour. Storage technologies in the electrical grid are capable to reduce the limitation in feeding the grid by renewables and to reduce the amount of reserve capacity. Fridges in households use electrical energy to cool food. With the integration of a latent heat storage and the high number of fridges already in use can be generated a remarkable dispatchable electrical load, without any loose of comfort for the user. First studies have showed that thermal storages are capable to provide lower costs per stored kilowatt-hour compared to Li-ion battery.

Prime focus of the project is the integration of latent heat storage in a fridge to provide a dispatchable electrical load.

Different integration methods of the latent heat storage will be theoretically investigated. The most promising solution will be carried out and optimized step by step with different test storages.


In a theoretically study the economic and technical potential of the desired technology will be investigated and compared to battery based storages. The marginal costs of the storage will be estimated with the expected price difference for electrical energy between peak and part load. Furthermore the influence of the fridges equipped with latent heat storage to the grid will be estimated.

In the work package "storage integration and fridge model selection" a fridge type with high market penetration will be selected. An integration concept which maintains a high efficiency of the fridge with acceptable costs and complexity will be designed.

In the work package "storage development" several storages will be built and step by step optimized in its key features heat transmission and long term stability.

The chosen fridge will be modified to build in the latent heat storage.  A fully function able fridge will be built and tested.

The latent heat storage will be cycled to prove long term stability.

To investigate in which way  a user can influence the system, it will be checked if it is possible to build several demonstrators  to test the new fridge under real life conditions in a field test.

The potential studies from the project begin will be updated with data collected during the project to document the achieved sate of the art.

Supported by: The Federal Government on the basis of a decision by the German Bundestag


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  • Dr. Stefan Hiebler
    Bayerisches Zentrum für angewandte Energieforschung e.V. - ZAE Bayern
Other Addresses


Research funding

The information system EnArgus provides information on research funding, including on this project (German only).