Danish start-up Fenagy will supply a CO2 (R744) heat pump to Danish district heating provider Vestervig Fjernvarme, allowing the provider to use its old oil-fired boiler only as an emergency backup. 

In addition to shutting down its oil-fired boiler, the new heat pump will also allow Vestervig Fjernvarme to reduce the use of a 4.6MW wood-chip boiler, turning it off entirely during summer.

The H1200 air-to-water CO2 heat pump has a capacity of 1.2MW (341TR) at an ambient temperature of 5°C (41°F). It is “perfect” for the 70°C (158°F) water temperature required for the district heating system, with a return water temperature of 36°C (96.8°F), Fenagy said in a statement. The heat pump has an average annual coefficient of performance (COP) of 3.2.

Vestervig expects the new heat pump will help it keep customers’ heating bills low, and, of course, eliminate a significant amount of CO2 emissions, Fenagy said.

“There are several reasons why we chose a CO2 heat pump, one of them being that is has a flatter performance curve over the year,” said Morten Pipper from SEG Energy, an adviser to Vestervig Fjernvarme on the project. “In other words, the heat output decreases significantly less with falling ambient temperatures, meaning that heat output and demand match better.”

The heat pump solution will be installed in a separate, low-noise building also delivered by Fenagy, with the evaporators placed on the roof. In connection with the new heat pump, Vestervig will also install a 2,000m3 (70,629ft3) accumulation tank. This will benefit both the heat pump and the wood-chip boiler, as part load operation can be avoided, according to Fenagy.

“The district heating market is ready for the big heat pumps,” said Ebbe Nørgaard, Head of Sales for industrial heat pumps at Fenagy. “We’ve already seen installation of quite a few large heat pumps over 7MW (1,990TR), but now we see a growing market in the 1-5MW (284-1,422TR) area, where our technology will play a crucial role,” Nørgaard concluded.

Another Danish district heating provider, Saltum Fjernvarme, has taken delivery of an energy-efficient ammonia/NH3 (R717) heat pump system with a coefficient of performance (COP) of more than three.