Varanto - World's largest geothermal energy storage Vantaa
Overview
In Vantaa, a large neighboring city of Helsinki, the world's largest geothermal energy storage installation is being built, called Varanto. The goal is to store energy underground that can be used for district heating when needed. This is particularly relevant for Nordic countries, where heating demands vary significantly between the seasons. The costs are estimated at around €200 million, investment grants have already been received. Already today, 90% of the residences in the city of Vantaa receive their heat via a district heating network.
The storage will consist of three caverns, 20 x 300 x 40 meters, that will be excavated at about 100 meters below ground level. Those will be filled with water, reaching a temperature of 140 °C without boiling or evaporating. It will reach a total thermal capacity of 90 GWh which would be able to heat a Finish medium sized city for one year. This capacity is worth as much as €8 million for district heating. An equivalent of 1.3 mio electric car batteries will possibly be stored in the 1,100,000 cubic meters storage, filled with 140 °C water.
In practice, a hybrid system will be set up, combining waste heat, district heating and electricity generation. Two 60 MW electric boilers will connect the grid to Varanto to produce heat from renewable energy and use different energy sources at different times to have the most advantageous and efficient outcome.
Summary
Year of commissioning: 2024
Power production: estimated from of 2028
Installed thermal capacity: 90 GWh
Heat production per year: medium city heating requirements
Operator: Vantaan Energia
Well depth: 100m
Temperature: 140 °C