Lighthouse project ElKaWe

Electrocaloric heat pumps

In the lighthouse project »ElKaWe«, six Fraunhofer Institutes under the direction of Fraunhofer IPM are working on the development of electrocaloric heat pumps for heating and cooling. Today, heat pumps work almost exclusively based on compressor technology. Electrocaloric heat pumps promise significantly higher efficiency and do not require harmful refrigerants. As part of the project, the scientists are developing ceramic and polymer-based electrocaloric materials and are working on an innovative system concept that enables particularly efficient heat dissipation.

Work in the project is intended to demonstrate that electrocaloric heat pumps have the potential to replace compressors in the long term. Heat pumps are an important component of the energy revolution, as they ensure optimized space heating and hot water generation. Powered by electricity generated from renewable sources, they form the missing link between electricity and heat generation. However, the number of heat pumps for air conditioning in buildings is growing slowly because compressor-based heat pumps are economically inefficient. In cooling technology, the gradual ban on refrigerants within the framework of the European »F-gas Regulation«, which aims at reducing fluorinated greenhouse gases, also makes alternative technologies desirable.

How does an electrocaloric heat pump work?

If an electric field is applied to electrocaloric materials, the electric dipole moments in the field are aligned. This additional order is accompanied by heating of the material according to the laws of thermodynamics. The resulting heat is dissipated via a heat sink so that the material cools down again to the initial temperature. If the electric field is removed, the order is reduced and the material cools down to a temperature below the initial temperature  – again in accordance with the laws of thermodynamics. Now it can absorb thermal energy from a heat source. The effect is reversible. In this way, a cycle can be set up that functions as an efficient heat pump for cooling or heating.

Project details


Project start
October 1, 2019

End of project
September 30, 2023 (originally). Additional funds of approximately 980 thousand euros were authorized for the project in light of the scientific successes. The project duration was extended by 15 months. The project ends on December 31, 2024.

Fraunhofer IPM

Fraunhofer Lighthouse Project


Presse release Fraunhofer IAF / 20.7.2023

Power electronics for novel heat pumps achieve efficiency of over 99.7 percent

As part of the ElKaWe project, researchers at Fraunhofer IAF have successfully realized a circuit topology for voltage converters with over 99.74 percent electrical efficiency. The power electronics are intended for use in electrocaloric heat pumps.


Review: Scientific events 2022

Trade Fairs | Conferences

Chillventa, October 11–13, 2022

At the trade fair for refrigeration technology, we presented innovative concepts for a new generation of heat pumps together with Fraunhofer ISE. Electrocaloric heat pumps, which have been developed as part of the ElKaWe project were part of the exhibition. We were met with great interest from the refrigeration community!


Conference | Invited talk

Calorics 2022
September 12–14

At the Calorics 2022 conference, Kilian Bartholomé from Fraunhofer IPM has given a presentation with research finding from the ElKaWe project:  


»Electrocaloric cooling«

(Kilian Bartholomé, Fraunhofer IPM; Fred Fietzke, Fraunhofer FEP; Sylvia Gebhardt, Fraunhofer IKTS; Dirk Lellinger, Fraunhofer LBF; Michael Wegener, Fraunhofer IAP; Patrick Waltereit, Fraunhofer IAF)

Scientific publications within the project

Publication Type
2023 On the efficiency of caloric materials in direct comparison with exergetic grades of compressors
Schipper, Jan; Bach, David; Mönch, Stefan; Molin, Christian; Gebhardt, Sylvia; Wöllenstein, Jürgen; Schäfer-Welsen, Olaf; Vogel, Christian; Langebach, Robin; Bartholome, Kilian
Journal Article
2022 A GaN-based DC-DC Converter with Zero Voltage Switching and Hysteretic Current Control for 99% Efficient Bidirectional Charging of Electrocaloric Capacitive Loads
Mönch, Stefan; Mansour, Kareem; Reiner, Richard; Basler, Michael; Waltereit, Patrick; Quay, Rüdiger; Molin, Christian; Gebhardt, Sylvia; Bach, David; Binninger, Roland; Bartholome, Kilian
Conference Paper
2022 Enhancing Electrocaloric Heat Pump Performance by Over 99% Efficient Power Converters and Offset Fields
Mönch, Stefan; Reiner, Richard; Waltereit, Patrick; Molin, Christian; Gebhardt, Sylvia; Bach, David; Binninger, Roland; Bartholome, Kilian
Journal Article
Diese Liste ist ein Auszug aus der Publikationsplattform Fraunhofer-Publica

This list has been generated from the publication platform Fraunhofer-Publica

Sub projects

Overall system and simulation

As part of the project, Fraunhofer IPM is developing a system design for an efficient electrocaloric heat pump. The heat transfer between the electrocaloric material and the heat transfer unit is realized according to the principle of a heat pipe via a combination of evaporation and condensation of a fluid (e.g. water) and a thermal diode. No harmful refrigerants are used in the process. This novel, patented approach ensures heat transfer rates that are many times higher than those of previously known solid-state-based heat pumps.


Experimental platform for setting up an electrocaloric heatpump  

Projekt ElKaWe: Experimentier-Plattform für den Aufbau elektrokalorischer Wärmepumpen
© Fraunhofer IPM
Measurement platform for the characterization of electrocaloric segments.
ElKaWe project: Laboratory platform for the construction of electrocaloric heat pumps
© Fraunhofer IPM
Electrocaloric segment integregrated into a measurement platform.
ElKaWe project: Laboratory platform for the construction of electrocaloric heat pumps
© Fraunhofer IPM
Electrocaloric segment

Ceramic materials and components

As part of the project, Fraunhofer IKTS is developing electrocaloric materials and components based on ceramic materials and technologies. The focus is on the synthesis and targeted modification of functional ceramic materials for high reversible temperature changes in the range of the application temperature. Robust electrocaloric components with high dielectric strength are manufactured via film casting and ceramic multilayer technology. The manufacturing process of multilayer ceramic capacitors (MLCC), which is well established in microelectronics, allows components to be manufactured for integration into solid-state heat pumps that are suitable for series production.

Hybrid materials

During this project, Fraunhofer IAP is developing electrocaloric materials and components based on polymers and, in cooperation with Fraunhofer IKTS, also on hybrid materials. As part of the development of electrocaloric-active polymers, Fraunhofer IAP is investigating the processing of various terpolymers with relaxor-ferroelectric properties in different layer thicknesses. In addition, the optimization of intrinsic material properties with regard to high electrocaloric effects is to be researched. On the basis of these optimized polymer materials, electrocaloric-active components will then be developed using, among other things, layering or stacking processes and made available for integration into the overall system. Alternatively, electrocaloric-active ceramic particles dispersed in an electrocaloric polymer matrix are used to develop hybrid materials that also have an electrocaloric effect.


Fraunhofer FEP develops and applies all surface coatings required for the function of the electrocaloric heat pump. Regardless of their thickness of only a few micrometers, they are capable of fundamentally changing the property profile of the component surface in question and adapting it to the application. Specifically, these are layers for electrical insulation of the active components, for adjusting the wetting behavior of the surfaces in contact with the working fluid, and for protecting the materials used from the ingress of foreign gases and from corrosion. All layers are applied by means of vacuum-based processes (PVD, CVD).

Electrical control

Fraunhofer IAF develops power electronics of the electrocaloric cells. For this purpose, the dielectric loss properties of the cells are first comprehensively measured as a function of voltage, temperature and frequency and a simulation model is created. Based on this, the control of the cells is designed to be as energy-efficient as possible in a second step. Tailor-made innovative semiconductor components are to maximize the efficiency.

System Reliability and durability

Fraunhofer LBF is contributing its many years of experience in materials research of polymer-based electroactive materials to the project. The characterization and reliability analysis of these materials, the simulation of their behavior and the development of system-theoretical reliability models of the components and the overall system are the focus of the research.


Further information

Caloric Systems

We are conducting research into magnetocaloric, elastocaloric and electrocaloric systems for cooling and heating.