After a successful test phase, which met all requirements and showed a higher COP than promised, the Danish renewable energy and storage specialist, Aalborg CSP, has commissioned yet another heat pump order. The 1.2 MW air-to-water CO2 heat pump system was handed over to the client, the Danish district heating plant Solrød Fjernvarme.

The increase in fossil fuel prices has for many contributed to an acceleration of the green energy transition. In recent years, an increasing number of Danish district heating plants has turned their attention towards alternative solutions such as heat pumps. One of these district heating plants is Solrød Fjernvarme (Solrød District Heating).

Performance tests present a COP higher than promised.

The Danish district heating plant Solrød Fjernvarme is experiencing an increased demand following an expansion of the district heating network. The district heating plant’s newly commissioned heat pump thus contributes to ensuring sufficient heating capacity to supply both current and future district heating customers.

After a successful performance test phase, which met all requirements and achieved a higher COP (Coefficient of Performance) than promised, the heat pump system has been handed over to the client, Solrød Fjernvarme, who will be responsible for the day-to-day operation of the plant.

The order for Solrød Fjernvarme is a turnkey EPC contract consisting of a 1.2 MW CO2 heat pump, expansion of the existing technical building, and integration with the existing system, which includes a 2,569 m2 solar heating plant and a 1,250 m3 hot water accumulation tank.  

The integrated heat pump system, which is tailored to fit the district heating plant’s specific energy needs, uses outdoor air as the source for heat production and ensures a more flexible energy supply.

Natural and climate-friendly refrigerant.

Besides a sustainable heating solution, the client has likewise selected a sustainable and environmentally friendly natural refrigerant for their heat pump. The new heat pump system for Solrød Fjernvarme uses CO2 as a refrigerant.

Some of the synthetic refrigerants used today, such as HFCs and HFOs, are very problematic for the environment. Over time, parts of these gasses are converted into PFAS, which is considered potentially harmful to humans. Furthermore, these fluorinated greenhouse gases are problematic for the environment as they contribute to global warming.

CO2, on the other hand, is an environmentally friendly refrigerant that, in addition to being naturally occurring, is also highly energy efficient. It is considered non-toxic, does not affect the ozone layer, and is furthermore not contributing to global warming.

Aalborg CSP is not obliged to make use of one specific refrigerant. However, the company has deliberately deselected all forms of synthetic refrigerants as these not only harm the air but also the soil and oceans with their harmful content such as PFAS. Moreover, the company is not tied to one specific heat pump technology. Instead, the company supports its clients in finding the most suitable heat pump for their individual project. It is possible to use a wide range of natural heat sources ranging from outdoor air and industrial surplus heat to wastewater and liquid biomass.

Fossil-fuel free district heating sector by 2030

The district heating sector is an important part of the Danish commitment of a 70% reduction of greenhouse gas emissions by 2030. In Denmark, 66% of all households are connected to district heating networks and the sector is aiming at being 100% fossil-fuel free by 2030. Most district heating plants are already well on their way to becoming fossil-fuel free, combining multiple renewable solutions, such as solar thermal, heat pumps, and thermal heat storage.

The recently commissioned and delivered heat pump system in Solrød, Denmark, is not the first project that Aalborg CSP and Solrød Fjernvarme have collaborated on. In 2016, Aalborg CSP delivered a 1.9 MW solar heating system consisting of a 2,569 m2 flat panel solar field combined with a 1,250 m3 heat storage accumulation tank to the district heating plant.


Client: Solrød Fjernvarme
Capacity of the heat pump: 1,2 MW at 0 °C
System supplier: Aalborg CSP A/S in collaboration with Advansor and NatRef Engineering ApS
Scope: Turnkey EPC contract incl. technical building and civil works
Location: Havdrup
Type of heat pump: Tailor-made CO2 heat pump from Advansor