10 MW Heat Pump System to Boost a Volcanic District Heating Solution in Reykjavik

In 1973, a volcano erupted on the island of Vestmannaeyjar, spreading lava over half the town. Sveinbjörn Jansson from Reykjavik came up with the idea of utilising the heat from the lava for space heating, creating the world’s first and only volcanic district heating system. By 1988, the heat from the lava had reduced, making it necessary to find alternative energy sources for residential heating.

Vahterus, together with Johnson Controls, helped the local energy company HS Veitur hf develop a 10 MW heat pump system to boost the district heating system, a closed loop solution, where after usage, water gets pumped back to the boiling station for reheating from 34°C to 77°C. Four identical heat pump units, each with 2.5 MW heating capacity, were designed as a flooded NH3 economised system.

The heated water first enters the subcooler and condenser. After this, the flow is divided into one de-superheater and two oil coolers in parallel. The design of the system allows temperatures approx. 8–9°C higher than the condensing temperature, resulting in a superior COP. The new setup is expected to provide over 40 GWh/year of free ocean heat. The use of heat pumps requires around 75% less energy than the former boiler – a great improvement, both ecologically and economically.