Largest CO2 seawater heat pump starts up

DENMARK: A CO2-based seawater heat pump, said to be the world’s largest, has commenced operation supplying district heating networks in Esbjerg.

The heat pump, with a total heating capacity of 70MW, was supplied by Swiss company MAN Energy Solution AG to the new heat pump plant at the Port of Esbjerg. 

Operated by multi-utility company DIN Forsyning, the heat pump plant will supply approximately 280,000MWh of heat annually to the district heating networks of Esbjerg and the neighbouring town Varde. It will cover the heating needs of 25,000 households, while reducing CO2 emissions by an estimated 120,000 tons per year.

The plant harnesses renewable energy from nearby wind farms and seawater as a heat source. The facility is part of the transition to replace the city’s coal-fired power plant, which ceased operations, and forms a critical part of Esbjerg’s ambitious goal of achieving carbon neutrality by 2030. 

The MAN heat pump operates in tandem with a new 60MW wood chip boiler that uses sustainable wood chips and a 40MW electric boiler plant, which serves as a peak and backup load facility.

A key feature of MAN’s solution is its use of CO2 as a refrigerant, made more appropriate given the plant’s location on the shore of the Wadden Sea, a UNESCO World Heritage Site with a sensitive ecosystem. 

The solution also enables fast power-balancing of the electrical grid and thus supports the integration of intermittent power generation like solar and wind. The system can be switched on and off many times a day with fast reaction capability.

At the core of the plant are two oil-free, hermetically sealed HOFIM motor-compressor units developed and manufactured by MAN Energy Solutions in Zurich, Switzerland. These units use high-speed motors and active magnetic bearings, eliminating the need for oil and reducing maintenance requirements. The machines will be connected for remote monitoring, data-analytics and diagnostics of the compressor technology and the auxiliary systems.