Experts are clear: The potential of large heat pumps with a thermal output of 500 kilowatts or more is enormous. By 2040, they could supply around two-thirds of the energy needs of municipal heating networks in Germany, according to the German Association of Energy and Water Industries (BDEW). These giants absorb sustainable energy from the air, ground, or water and evaporate a refrigerant, which is then heated to a higher temperature by a compressor. In the next step, the energy is fed into a local or district heating network or used for industrial processes.
“Large-scale heat pumps and heat networks can make an important contribution to decarbonization in urban areas. If we want to achieve climate neutrality by 2045, they are an indispensable building block,” says Anna Billerbeck, an expert at the Fraunhofer Institute for Systems and Innovation Research ISI. For a long time, however, the construction of large-scale heat pumps in Germany was slow to get off the ground – just 60 megawatts of thermal capacity were in operation in 2023.
Investments in the technology seemed unprofitable, and successful practical examples were rare in this country. Although the technology is now considered mature on a large scale: According to Fraunhofer IEG, large heat pumps are established in district heating for flow temperatures up to 120 degrees Celsius and are available in series production for heating outputs up to one megawatt. However, off-the-shelf solutions are not available for systems larger than ten megawatts. Customized systems must be built to supply entire neighborhoods or even districts.
Billerbeck commented: “There is little experience with higher performance classes on the market so far. Especially in district heating, there is no single technical solution that fits all municipalities. If the heating load is very high in winter, additional heat generators may be needed that can be switched on.” In existing heating networks in Germany, heat pumps often have to reach very high temperature levels to heat buildings, such as older ones.
This reduces the efficiency of the pumps, making their operation expensive due to high electricity prices. Added to this are high investments in technology and infrastructure expansion. If the pumps cannot be integrated into an existing heating network, the municipal utilities lack the revenue to cover the costs.
A database from the Fraunhofer Institute for Energy Infrastructure and Geothermal Energy IEG shows that large heat pumps with a total thermal output of 180 megawatts were in operation at the end of June 2025. In addition, another 1.5 gigawatts are already being built or have been announced. One reason for this boost is municipal heat planning, which cities must submit by 2026 or 2028 – depending on their size.
According to the Heidelberg Institute for Energy and Environmental Research, many municipalities are relying on large-scale heat pumps. “The topics of neighborhood heating and district heating are gaining importance across Europe. Large-scale heat pumps play a key role in this and will in many cases displace or at least complement traditional combined heat and power plants,” says Christian Hüttl, Head of Heat Pumps at Siemens Energy. Another reason for the rising demand is the federal subsidy for efficient heating networks, which runs until 2028. Experts consider it essential to drive the expansion of green heat. After all, the high investment and operating costs do not pay for themselves.
More information is available here: BDEW
