Baltic heat pump to power 40% of Helsinki

A €400m, 500MW project to generate heat for the Finnish capital will extract deep water from the sea bed, even when the surface is frozen


1 Water in: 17km tunnel from sea bed – deep water stays at constant temperature
2 ̊C
0.5 ̊C

Refrigerant
Cooler than seawater

2 Water returned from city heating system 
Process can be reversed during summer for cooling
45 ̊C
88 ̊C

3 Expansion valve
Pressure drops, lowering  temperature of refrigerant

Low pressure 
High pressure

4 Evaporator: Refrigerant absorbs heat from water, causing it to evaporate

5 Compressor 
Raises pressure of refrigerant vapour causing temperature to increase

6 Condenser  
Heat from refrigerant transferred to water, condensing to liquid as it cools

7 Water out: 9km tunnel carries cooled water to sea

INPUT 1kW electricity (for pump)

8 Hot water for city heating

OUTPUT 6kW heat (5kW derived from seawater)

City also utilising heat from waste water and buildings to meet goal of carbon neutrality by 2050


Sources: Bloomberg, Helen Ltd
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