District heating with flexible
heat production and large energy storage
The case
In Nykøbing Sjælland, Denmark, four H-1800 air-source CO2 heat pumps enhance the district heating company’s heating system. The heating setup also includes a 10 MW electric boiler, a CHP unit and substantial energy storage in two accumulation tanks, ensuring optimal heat production regardless of the electricity price.
The energy storage holds 9,500 m³ of hot water, providing great flexibility to switch the units on and off in response to electricity price fluctuations, while consistently meeting the heating demands of approximately 2,000 consumers.
The heat pump
The heat pump installation consists of four standard H-1800 AW units and 24 evaporators, positioned in two groups of 12 opposite each other. The four H-1800 heat pumps are the first Fenagy units equipped with the highly efficient 70 m³/h 8-cylinder compressors from Bitzer. The heat pumps can start and stop in about 5 minutes and produce hot water up to 85°C, providing optimal flexibility for planning and operation.
The heat pumps were commissioned in 2023 and fully handed over to the customer after commissioning.
Year: 2023
Model: 3 x H-1800 AW
Application: Air-to-water heat pump
Capacity:
7.9 MW
42°C/70°C hot water (5°C/85% humidity)
Heat source: Air
COP: 3.0
Defrost method: Glycol
Combined wastewater and air-source heat pump for
district heating
The case
In Fårevejle, Denmark, a brand new district heating network is heated by a combination of air and wastewater. The wastewater heat pump handles the base load, while the air-source heat pump steps in if the demand exceeds the wastewater system’s capacity.
The heat pump
The heat pump installation consists of two standard H-1800 AW units and one H-1200 WW unit. The wastewater system includes two accumulation tanks from which energy is extracted. Before the water enters a water-to-water heat exchanger, it is filtered through a self-cleaning filter. Additionally, the heat exchanger is equipped with a clean-in-place system, ensuring reliable and stable operation. The wastewater can be cooled down to around 2°C allowing maximum energy to be extracted.
The heat pump was commissioned in 2023 and fully handed over to the customer after commissioning.
Year: 2023
Model:
2 x H-1800 AW · 1 x H-1200 WW
Application:
Air-to-water and water-to-water heat pump
Capacity:
AW: 3.5 MW · WW: 1.3 MW
40°C/70°C hot water (5°C/85% humidity)
Heat source: Air and wastewater
COP: AW: 2.9 · WW: 3.05
Defrost method: Glycol
Exploiting the fluctuating electricity market
with large-scale air-source heat pump
The case
In Vildbjerg, Denmark, three H-1800 air-source CO2 heat pumps complete the district heating company’s heating system. Alongside these heat pumps, the setup includes a 12 MW electric boiler, two 3.5 MWe CHP units, solar heat collectors and substantial energy storage in two hot water energy accumulators. Together, they ensure optimal heat production regardless of electricity prices.
The energy storage holds approximately 7,000 m³ of hot water, providing significant flexibility to switch units on and off in response to electricity price fluctuations while reliably meeting the heating needs of around 2,000 consumers.
The heat pump
The heat pump installation consists of three standard H-1800 AW units, each with six evaporators, positioned side by side. Thorbjørn Madsen, Director at Vildbjerg Technical Works, expresses his excitement about the installation, saying: “The heat pump optimises our existing electric boiler and CHP units, enabling us to exploit the advantages of the fluctuating electricity market”.
Due to special wind and weather conditions, the units have even produced snow while generating heat. This is just one example of the way large-scale air-source heat pumps can interact with the forces of nature, and why our technical experience and intelligent control systems are essential to ensure reliable, stable operation without unforeseen issues.
The heat pump was commissioned in 2023 and fully handed over to the customer after commissioning.
Year: 2023
Model: 3 x H-1800 AW
Application: Air-to-water heat pump
Capacity:
7 MW, 35°C/68°C hot water (5°C/85% humidity)
Heat source: Air
COP: 3.2
Defrost method: Glycol
Combined heating and cooling for biogas production
The case
The biogas plant in Tønder, Denmark, will be one of the largest plants in Europe when completed. Annually, it will process 900,000 tons of agricultural feedstock and industrial organic waste and produce 40 million Nm³ of biomethane, equivalent to 400 GWh per year – enough to cover the annual energy consumption of 20,000 households.
The biogas production process begins with feedstock from local farmers being delivered and loaded into storage tanks. Once inside, the feedstock is heated by an HCI heat pump to stimulate the production of biogas. The generated biogas then goes through a purification process, and once upgraded, it can be fed into the natural gas grid, replacing natural gas and contributing to a sustainable energy supply.
The remaining feedstock, after processing and gasification, is cooled by the HCI heat pump system. This cooling step captures the remaining energy and converts the degassed feedstock into an eco-friendly fertilizer. Essential nutrients are preserved, odour is reduced and the fertilizer is ready for use on fields.
The heat pump
The installation includes three HCI-3000 heat pumps, using isobutane as a refrigerant. Each HCI-3000 unit is installed in a sound-dampening enclosure, ventilated by an EX-fan to ensure a negative pressure and maintain the right temperature in the cabinet. The entire system is controlled by a Siemens PLC with added Fenagy algorithms for the most essential functions.
HCI heat pumps can deliver supply temperatures up to 95°C. The heat pumps have been commissioned and in operation since the summer of 2024. Tønder Biogas plant will be completed in 2025.
Year: 2024
Model: 3 x HCI-3000
Application: Water-to-water heat pump
Capacity: 5-7 MW
Heat source: Water
Refrigerant: Isobutane
Sector integration in the city
- waste heat from district cooling recovered for district heating
The case
In the heart of Copenhagen, a historic building is home to a new Fenagy heat pump installation by HOFOR, a key district heating and cooling provider in the city. This heat pump is the first of 10 planned units, which together are expected to replace up to one-third of the biomass currently used for heating and will eventually provide heat to approximately 130,000 apartments.
The heat pump utilises waste heat from HOFOR’s district cooling facility at the same location. In the summer, excess heat in the district heating network can be rejected into seawater taken from the city harbour. As the electricity used comes from wind and solar energy, the project is an excellent example of effective sector integration.
The heat pump
The heat pump installation consists of two H-1800 WW units and one H-1200 WW unit, customised to meet the specific requirements of this unique location, which has very limited space and strict noise regulations. The racks are slightly shorter than usual, with larger pumps integrated on both the cold and warm sides. Additionally, the compressor compartments are sound attenuated using specially designed panels, reducing noise levels from Lw = 105 dB(A) by 4-5 dB. The heat pumps are equipped with special vibration-reducing machine feet to prevent vibrations from being transferred to the machine room.
The three racks are positioned at two levels on a steel frame. The heat pump uses CO2 as a refrigerant, which is an optimal choice for a mid-city location in terms of safety. It supplies heat to approximately 2,500 homes in Copenhagen.
The heat pump was commissioned in the autumn of 2024 and was fully handed over to the customer after commissioning.
Year: 2024
Model:
2 x H-1800 WW · 1 x H-1200-WW
Application:
Combined district cooling and district heating
Capacity: 3.3 MW cooling · 4.9 MW heating
47°C/75°C hot water, 12.5/5.5 cold water
Heat source: Water
COP: 2.7
Aalborg utility has installed a district cooling plant at IKEA Aalborg
The case
For a long time, the facility management of the warehouse had been dealing with an outdated chiller unit in need of replacement. To address this issue and replace the old HFC chiller unit, the team invested in a modern CO2 heat pump with integrated chiller application. The solution was implemented in collaboration with Aalborg Utility company, using heat pump units designed and manufactured by Fenagy A/S and installed by Krebs A/S.
The aim of the project was to establish a carbon-neutral cooling system for the warehouse. To achieve this, the waste heat generated from the chiller production is directed to the district heating network. The combined unit is designed to supply chilled water, heated water, or a combination of both.
The heat pump
The heat pump is fully installed in a premium enclosure, equipped with Fenagy’s latest ejector technology, FenEject, and controlled by a Fenagy PLC, with algorithms for capacity, chiller, evaporator and defrosting control. The installation is supported by four energy collectors, installed on 2-metre-high legs resting on a concrete foundation. Below these collectors, an aqua drain system has been established to collect condensate during defrosting. With a cooling capacity of 750 kW during the summer months, the heat pump not only meets the warehouse’s cooling needs, but it also channels waste heat into the district heating network. By all means, a sustainable and efficient solution.
Year: 2022
Model: H-1200 AW / WW - 4+4B
Application:
Air-to-water and water-to-water heat pump
Capacity (heat):
1200 kW (5 °C evaporation, 72/40 °C hot water)
Capacity (cooling): 8/13 °C hot water
Heat source: Air
COP: 3
Defrost method: Glycol
“We experience that district cooling becomes more and more sought after. The energy centre at IKEA is prepared for more customers in the area to connect - and there is great interest in that – just as district cooling is also expanding elsewhere in Aalborg.”
– Aalborg Utilities
District heating company expands existing
biomass-based production in Sdr. Felding
The case
The district heating company in Sdr. Felding, Denmark, has expanded its existing biomass-based production facilities with the integration of a large heat pump, a sizable buffer tank and a 10MW electrical boiler. This visionary installation exemplifies the future of district heating, which will be emission-free, and the installation serves as an important player in balancing the electrical grid. Notably, it has the capability of absorbing large quantities of green electricity during periods of abundance, and then utilising the stored energy from the tank during times when the electricity supply is lower than the demand.
The heat pump
Fenagy has provided two H1800 air-sourced heat pumps, including 12 flatbed evaporators, and the installation is executed by Krebs A/S. The heat pumps are equipped with Fenagy’s latest ejector technology, FenEject, optimised evaporators, and controlled by a Fenagy PLC, which has algorithms for capacity control, evaporator control and defrost. The control system can start and stop the machines so fast that they are well-suited and relevant for electrical grid balancing.
Year: 2022
Model: 2 x H-1800 AW
Application: Air-to-water heat pump
Capacity (heat):
3.5 MW (0° C ambient, 35/70° C hot water)
COP: 2.96
Defrost method: Glycol
Transportable air-source heat pump
The case
Fenagy’s very first heat pump – a 600 kW air-to-water unit – was developed and designed during the autumn of 2020.
The heat pump was installed at a biomass-fired district heating system in a small city outside Aarhus, where it operated in combination with a straw boiler and oil boilers for peak load and back-up. The heat pump served as both a test unit and a demonstration unit.
The heat pump
Fenagy received DKK 250,000 in support from the Green Investment Pool, and Kredsløb utility company in Aarhus purchased the heat from the heat pump for the district heating network. During the test period, Fenagy paid a fixed price
for electricity, and Kredsløb paid a fixed price for the heat. When this agreement expired, the operation of the heat pump needed to be changed in order to still be cost-effective, and as the demonstration site had fulfilled its purpose, Fenagy decided to move the heat pump.
Moving the unit
In 2023, the heat pump was sold and moved to a different district heating plant in Djursland, Trustrup/Lyngby, where it supplies heat to the small town Balle – approx. 50 kilometres away from the original site. The move was done in just 2-3 weeks showing that a factory-built unit from Fenagy provides a great opportunity to buy a mobile unit for consumers in areas where a transmission line for district heating has not yet been established. They can buy a heat pump first and then connect to the district heating once this is established.
Year: 2021/2023
Model: H-600 AW
Application: Air-to-water heat pump
Capacity (heat): 600 kW
(5°C ambient, 40/70°C hot water)
Heat source: Air
COP: 2.9
Defrost method: Glycol
Mejlby District Heating installs a heat
pump in the middle of a residential area
The case
The district heating company in Mejlby has expanded its production facilities with an electrically driven heat pump. They wanted a heat pump for base load operation to reduce gas consumption. The existing gas boiler now serves as back-up and for peak load operation. Together with their gas driven CHP system, they can now produce cheap heat, both when the electricity price is high and low
The heat pump
The heat pump is installed in a Fenagy premium enclosure, delivered plug-and-play, and placed outside the existing buildings on the site. The enclosure is soundproof, ensuring that the 35 dB(A) noise requirements of the residential area, where Mejlby district heating is located, are met. Outside air evaporators are installed right next to the heat pump enclosure and run silently.
The heat pump is running almost constantly because the gas boiler alternative is more expensive to operate, but in periods with high electricity prices, the existing gas motor can be used to produce electricity, and the heat pump can be shut down.
The heat pump is a standard CO2 air-to-water heat pump, equipped with the latest Fenagy ejector technology, FenEject, and controlled by the Fenagy PLC with algorithms for capacity control, evaporator control and defrost.
Year: 2022
Model: H-1200 AW
Application: Air-to-water heat pump
Capacity (heat): 1.3 MW
(0°C ambient, 32/70°C hot water)
Heat source: Air
COP: 3.34
Defrost method: Glycol
Combined heat and power plant in Haderup
The case
Haderup Utility Company provides the city with district heating from a setup that comprises a combination of a heat pump, a gas motor, a gas boiler (CHP) and solar heat. The peak load on the demand side is 1.8 MW.
The operation depends on the heat demand from the consumers, the stored energy, the electricity prices and system services related to balancing the electrical grid. This makes the plant at Haderup Utility Company both efficient and flexible. The heat pump uses the latest ejector technology and together with the parallel compression, it results in an SCOP around 3.0.
The heat pump
The heat pump is installed inside the main building, positioned in a dedicated machine room next to the gas boiler and gas engine. It is equipped with the latest Fenagy ejector technology, FenEject, and controlled by the Fenagy PLC with algorithms for capacity control, evaporator control and defrost.
Year: 2021
Model: H-1200 AW -4+4B
Application: Air-to-water heat pump
Capacity (heat): 1.2 MW (5 °C ambient)
Heat source: Air
Defrost method: Glycol
COP: 2.84
“It will provide Feldborg and Haderup with a stabilization of
the heating cost by adding a fourth production unit.”
– Thorbjørn Madsen, Director - Vildbjerg Technical Facilities
CO2 cooling and freezing for Liertoppen logistics centre
The case
Liertoppen is an 18,500 m3 logistics centre for Oda in Oslo, which is the largest online food distributor in Norway. In collaboration with Therma Industri A/S, Fenagy has provided a cooling and freezing application to the storage and packing area at the distribution centre.
The units
Fenagy has delivered two chiller units and a freezing unit. One of the chiller units provides 800 kW glycol at -2/-6 °C, and the other is providing 800 kW chilled water at 10/5 °C. Both units are installed with a heat recovery system. The freezing unit is connected to the glycol chiller, providing 100 kW freezing capacity at -32 °C evaporator temperature. The installation is controlled by FenControl ensuring a stable and efficient control and monitoring of the installation.
Year: 2021
Model: 2 x C-1000
Application:
Cooling and freezing application with heat recovery
Capacity (kW): 100 kW freezing DX -32 °C,
800 kW cooling (30% glycol) -2/-6 °C and
800 kW cooling 10/5 °C
Air-to-water heat pump supplying heat for greenhouse
The case
Kronborg is a Danish horticulture company with a 45,000 m2 greenhouse. The company wished to be able to produce heat for the greenhouse during wintertime, and this is now in place with an energy-efficient heat pump using the natural refrigerant CO2.
The heat pump
A standard Fenagy heat pump is built on a rack. It is placed in a machine room on the customer site and connected to the central heating system on the hot side. The heat pump rack is connected to four evaporators, which are located outside. The system is equipped with the latest Fenagy ejector technology, FenEject, and controlled by the Fenagy PLC with algorithms for capacity control, evaporator control and defrost.
Year: 2022
Model: H-600 AW
Application: Air-to-water heat pump
Capacity (heat):
632 kW (5 °C ambient, 30/60 °C hot water)
Heat source: Air
COP: 3.7
Defrost method: Glycol
Air-to-water heat pump combined with a wood chip boiler and storage tank in Vestervig
The case
The district heating company in Vestervig has expanded its production facilities with an electrically driven heat pump and a large water storage tank. They wanted to be less dependent on the wood chip boilers and be able to shut down the boilers for maintenance during summer. Due to limited space and a location in the town centre, low noise and prevention of cold air recirculation were high priorities. For this reason, the evaporators are elevated 5 metres above the ground with noise barriers installed around them.
The heat pump
The heat pump is installed in a Fenagy premium sound enclosure outside the existing buildings. It is equipped with the latest Fenagy ejector technology, FenEject, and controlled by the Fenagy PLC with algorithms for capacity control, evaporator control and defrost. The measured capacity without defrost is 1,493 kW with an ambient temperature of 6.5 °C, hot water temperatures 33/70 °C and a relative humidity of 70%. This gives the heat pump a COP of 3.05.
Year: 2021
Model: H-1200 AW 3+3D
Application: Air-to-water heat pump
Capacity (heat): 1.2 MW (5 °C ambient,
36/70 °C hot water)
Heat source: Air
COP: 2.8
Defrost method: Glycol
Air-to-water heat pump in enclosure in Havneby
The Case
The district heating company in Havneby, Rømø, has expanded its production facilities with the integration of an electrically driven heat pump. The heat pump was an extension of the existing setup consisting of two wood chip boilers and an oil boiler on Havneby’s site, providing heated water to the accumulation tank. As the heat pump is installed in the harbour area where there is risk of flooding during westerly storms, the entire structure with the enclosure, electrical transformer and the evaporators is elevated approximately 100 cm above the ground.
The heat pump
The heat pump is installed in a Fenagy premium sound enclosure outside the existing buildings. It is equipped with the latest Fenagy ejector technology, FenEject, and controlled by the Fenagy PLC with algorithms for capacity control, evaporator control and defrost.
Year: 2022
Model: H-600 AW
Application: Air-to-water heat pump
Capacity (heat): 653 kW
(11 °C ambient, 38/70 °C hot water)
Heat source: Air
COP: 3.2
Defrost method: Cold gas
