Haderslev District Heating Utility
- Denmark’s largest CO₂ air-source heat pump to date
The Case
In 2024, Haderslev district heating in Denmark expanded its facilities with a new energy plant, which includes Denmark’s and probably the world’s largest CO₂ air-source heat pump to date. The machine room is inside a 2,000 m2 new building and holds five CO₂ heat pumps, a chiller (with heat recovery) and two defrost units. In connection with the new building, an electric boiler (15 MW) and a 5,000 m³ accumulation tank have also been installed. Finally, a new transmission line has been established from the energy plant to the local consumers in Haderslev.
The expansion was driven by an expected increase in heat demand, as many residents have transitioned away from natural gas. With the new energy mix, the Haderslev plant increases the share of green heat in the network, improves both flexibility and supply security – and not least, reduces heating costs for consumers.
For Fenagy, this project represents our largest commissioned heat pump installation to date.
Five H-2600 CO₂ heat pumps in the new machine room
The heat pumps
The installation consists of five H-2600 air-source CO₂ heat pumps, with a total heating capacity of 12 MW. While wood chips will remain the primary heat source, the heat pumps are expected to meet the entire heat demand during summer periods.
40 evaporators - energy collectors – are installed outside the machine room to draw heat from the ambient air. Down the middle is a covered walkway with integrated electrical panels to ensure safe and easy access for service and maintenance of the evaporators.
In addition to the heat pumps, Fenagy has supplied a C-300 chiller (with heat recovery), also using CO₂ as refrigerant, delivering 140 kW of cooling to the machine room and transformer room. The excess heat from this process is recovered and fed directly into the district heating network.
The accumulation tank on site is 5,000 m³ and can store up to 300 MWh of heat. With this storage, the heating plant can produce extra heat when electricity prices are low, store it in the accu-tank and supply it to the district heating network when prices are high. This setup increases operational flexibility and reduces the overall energy costs.
In total, the heat pumps can supply enough heat for more than 2,000 households.
C-300 chiller unit (with heat recovery) for cooling of machine room and transformer room
Year: 2024
Heat pumps: 5 x H-2600 AW
Application: Air-to-water heat pumps
Heat capacity: 12 MW (34°C/76°C return and flow (4°C/85% ambient conditions)
Chiller (with heat recovery): C-300 15°C/7°C cold side, 34°C/76°C warm side
Cooling capacity: 140 kW
Accumulation tank: 5000 m3
