World's largest CO₂ heat pump put into operation in Denmark

The world's largest CO₂-based seawater heat pump has been put into operation in Esbjerg, Denmark. The system, which is operated by utility company DIN Forsyning, is expected to supply around 280,000 MWh of climate-neutral heat per year for the district heating networks in Esbjerg and Varde – enough for 25,000 households. The manufacturer is MAN Energy Solutions.

The 70 MW plant uses seawater as a heat source and draws electricity from nearby wind farms. According to the heat pump manufacturer, it replaces a decommissioned coal-fired power plant and is operated together with a 60 MW wood chip boiler and a 40 MW electric boiler system. The plant is expected to save 120,000 tons of CO₂ per year.

4000 liters of North Sea water per second

The project on the west coast of Denmark was announced in June 2023. Around 4,000 liters of North Sea water would be extracted from the port every second. Even in cold temperatures, such as now in winter, this would provide enough heat energy to evaporate carbon dioxide before the water is returned to the sea. Electricity from renewable energy sources is then used to compress the vaporized CO₂ to temperatures high enough to boil water. A heat exchanger then transfers the CO₂ heat to water, which reaches households via the existing district heating network.

The system can react flexibly to fluctuating electricity generation from wind and solar power plants. For every megawatt hour of electricity used, the heat pump generates around three megawatt hours of thermal energy.

Blueprint for other cities?

At the heart of the system are two oil-free HOFIM motor compressors with magnetic bearings, which were developed in Zurich. The technology is intended to serve as a blueprint for other cities in the transition to climate-neutral heating systems – at least for those that have a district heating network. Esbjerg wants to become CO₂-neutral by 2030. The plant replaces an old coal-fired power station.

(mki)