Weska Kälteanlagen, a German industrial refrigeration and heat pump manufacturer, is constructing an 8MW (2,275TR) ammonia (R717) geothermal heat pump to supply district heating to more than 6,000 households in the Wilhelmsburg district of Hamburg.
The project, designed by Hamburg Energy Geothermal (Hamburg Energie Geothermie), a subsidiary of Hamburg Energy Utility (Hamburger Energiewerke), taps into a 48°C (118.4°F) geothermal reservoir located 1,300m (4,265ft) below the surface of Wilhelmsburg. The utility has already completed groundwater circulation testing and is laying a pipeline to connect the district to the heat pump system.
“We want to make the most of our geothermal heat,” said Thomas-Tim Sävecke, Head of Engineering at Hamburger Energiewerke. “That’s why our engineers and Weska have designed a highly efficient and technologically unique heat pump system.”
The design: The custom-built system consists of two four-stage ammonia heat pumps, which raise the 48°C pumped geothermal water to the required 75‒85°C (167‒185°F) temperature for the district heating network.
- Each heat pump contains three circuits, with an ammonia charge of 400kg in two of the circuits and 1,800kg in the other, Jörg Fuhrmann, Weska’s Managing Director, told NaturalRefrigerants.com.
- Each of the four stages lifts the temperature by 4‒5K, according to Furhmann.
- “Thanks to the planned multi-stage heat pump process, the usable thermal energy – and thus the number of households supplied – can be increased from an originally calculated 4,700 to over 6,000,” Hamburg Energy Geothermal said.
Expected efficiency: The system will operate with a COP of up to 4.5, according to Weska.
- “With the geothermal energy compressed in a four-stage process, we need comparatively little electricity to reach the required temperature level for district heating,” Sävecke said.
Similar installations: Heat pumps for district heating continue to gain popularity in Europe, with several utilities opting for ammonia systems.
- A 27MW (7,677TR) ammonia-based system ‒ comprised of four Johnson Controls’ Sabroe brand HicaHP heat pumps ‒ provides heating for 20,000 households in Utrecht, the Netherlands, using heat from a wastewater treatment plant.
- Four GEA heat pumps with Grasso L XHP screw compressors provide 24MW (6,824TR) of district heating in Tallinn, Estonia, using recovered heat from a biomass incinerator at a combined heat and power plant.
- A two-stage ammonia (R717) heat pump from Sabroe provides 700kW (199TR) of district heating to up to 800 households in Neustadt in Holstein, Germany, with the Baltic Sea as a heat source.
Quotable: “For Weska, the geothermal heat pump project represents a benchmark in performance and application, setting technology and efficiency standards,” Fuhrmann said. He added that manufacturing large heat pumps represents a new business area for the company.
“For Weska, the geothermal heat pump project represents a benchmark in performance and application.”
Jörg Fuhrmann, Weska’s Managing Director
