Finland’s largest rock cavern heat storage planned for Helsinki
Helen is planning to build a new energy storage facility in disused underground oil caverns located deep in the bedrock of Helsinki. The facility will be the largest of its kind in the country. The storage facility would accommodate over 40 times as much hot water as the amount of water in the pools at the Helsinki Swimming Stadium.
— Energy storage is a solution independent of the production technology and fuel, and it fits neatly into our current city energy system. Storage contributes to reducing the use of fossil fuels, increasing renewable energy and efficient recycling of waste heat, says Director Heikki Hapuli of Helen.
Energy use has peaks in consumption at daily and annual levels. The energy system needs an increasing amount of flexibility due to renewable energy sources and efficient recycling of waste heat. Helen already has heat storage facilities at the Vuosaari and Salmisaari power plants. The planned rock cavern heat storage facility is ten times as large as the Vuosaari facility and it would raise the optimisation of Helen's energy production to a new level.
Three large oil caverns used for the storage of heavy fuel oil are located underground in Mustikkamaa. The oil storage facilities were decommissioned and vacated in 1999. Two of the rock caverns are identical and they can be converted for heat storage use. The volume of the storage facility would be about 260,000 m3.
The designed storage project will be implemented if its technical and financial conditions are met.