MAN Energy Provides Heat Pump for Seawater-Driven Heating Plant

Aalborg Forsyning submitted a follow-up order with MAN Energy Solutions for a fourth heat pump unit, increasing its district heating plant’s total capacity to 177 MW. Each heat pump has approximately 44 MW capacity, and the plant will supply up to 700,000 MWh of heat per year—equivalent to one-third of Aalborg’s total heat production. Aalborg Forsyning submitted the first heat pump order in 2023.

“This follow-up order from Aalborg Forsyning underscores their trust and confidence in our heat pump technology,” said Mikael Adler, Head of Sales and Project Management Heat Pumps at MAN Energy Solutions. “We are excited to continue our collaboration on this project and are pleased to support Aalborg on its path to net-zero. The integration of this fourth heat pump unit will further enhance the environmental benefits of the city’s district heating network.”

MAN Energy has two partners for the project: Bilfinger will design and build the mechanical systems, while ACS will handle the design and implementation of electrical infrastructure. The contract scope includes a long-term service agreement with MAN PrimeServ; its Assist application will be used for real-time monitoring, data analytics, and diagnostics of compressor technology.

The district heating plant is on the Limfjord Strait’s northern bank in Denmark, leveraging seawater as a readily available heat source. Heat pumps will use renewable electricity to elevate water temperature from 1-15º C up to 98º C—the required temperature for district heating applications. The project will cut annual CO₂ emissions by up to 210,000 tons compared to Aalborg’s coal-fired power plant, planned for closure in 2028.

HOFIM compressor-driven heat pump; Image Credits: MAN Energy Solutions

“We are delighted to expand the overall heating capacity in collaboration with MAN Energy Solutions,” said Jesper Høstgaard-Jensen, Technical Director at Aalborg Forsyning. “These seawater heat pumps are the key part of our transition from coal-based to climate-friendly district heating, providing flexible heat at a very high temperature. Additionally, it is a clear advantage that MAN’s technology uses a natural refrigerant, making it well-suited for heat-pump operation at such high district-heating temperature.”

In heat pump operation, every MWh of electrical energy invested generates approximately 3 MWth of usable thermal energy. MAN Energy’s unit uses toxicologically- and environmentally-safe CO₂ to refrigerate the system-cycle. It also enables electrical grid power-balancing, supporting the integration of intermittent energy sources like solar and wind.

Aalborg’s planned heat pump plant will use four oil-free, hermetically sealed HOFIM motor-compressor units manufactured and tested by MAN Energy in Zurich, Switzerland. With a high-speed motor and active magnetic bearings, the compression unit operates without dry gas seal and lube oil systems.

Last week, Scout Motors Inc. ordered MAN Energy’s large-scale heat pump system for its new 1,100-acre electric vehicle (EV) production facility in Blythewood, SC, designed to produce over 200,000 EVs per year. To address the facility’s heating and cooling demands, MAN Energy will install the heat pump solution featuring two compressors, each delivering a 12.5 MW output. It will generate heat during mild winter months and cooling throughout summer by transferring thermal energy from ambient air.

The 25 MW adaptable system includes two five-stage RH71 heat pump compressors—both units provide cooling, while a single compressor can satisfy heating requirements. In addition, the order includes electric motors and process equipment such as condensers, coolers, evaporators, piping, and a control system.