District and process heat supply through heat pumps as a substitute for coal combustion

The planned phase-out of coal by 2038 not only makes an important contribution to reducing CO2 emissions, it also has a direct impact on the heat supply. Power plants that still provide district and process heat today will no longer be available in the foreseeable future and will have to be replaced by climate-neutral technologies. Large-scale heat pumps (LHP) and high-temperature heat pumps (HTHP) could take over this task in the future. As a basic technology that creates the foundation for the integration of renewable energies, they play a central role in the energy transition.


Numerous obstacles still hamper the dissemination of large-scale heat pumps (LHP) and high-temperature heat pumps (HTHP) and prevent penetration of the technology market. Large-scale heat pumps have comparatively long payback periods, so they are only competitive to a limited extent from an economic perspective. In addition, there is a lack of well-founded knowledge and many years of experience regarding the economic application potential. From a technical point of view, providing heat at the required high temperature levels while maintaining high output and efficiency is still a challenge. In order to meet the growing demands, it is necessary to think about the further development of the technology and the refrigerants to be used.

The project addresses these challenges and deals with the technical and economic obstacles that currently still hinder the widespread use of large-scale heat pumps and high-temperature heat pumps. The Fraunhofer IEG is leading the project.




The project provides answers to important questions that arise when integrating large-scale heat pumps (LHP) and high-temperature heat pumps (HTHP) into district and process heat supply systems:

  • Which renewable temperature sources are suitable for use by LHP and HTWP?
  • What requirements do district heating networks place on LHP?
  • In which direction do the constructional elements of LHP have to be further developed?
  • Which refrigerants are suitable for use in LHP?
  • How can the economic efficiency of LHP be improved with the help of suitable operating strategies?
  • What needs to be taken into account from a techno-economic perspective in the system integration of LHP?
  • Which framework conditions stand in the way of a higher market penetration of LHP and can these be changed?
  • What potential do HTHP have for the provision of process heat and how must they be technologically developed?

As a project partner, Fraunhofer ISI is developing an overview of the current economic framework conditions for LHP and is providing support for analyses on the use of HTHP for industrial process heat.



from October 2021 until September 2025


  • The Federal Ministry for Economic Affairs and Climate Action (BMWK)


  • Fraunhofer IEG (Projektleitung)
  • Fraunhofer ISE
  • Johnson Controls
  • AGFW
  • Stadtwerke Cottbus