Varanto - World’s Largest Cavern Thermal Energy Storage (Vantaa, Finland)

When completed in 2028, Varanto will be the world’s largest seasonal thermal energy storage facility in terms of size (1,1 million cubic meters) and capacity (90 GWh). The seasonal thermal energy storage facility will be built in Vantaa’s bedrock, where a total of three caverns about 20 meters wide, 300 meters long and 40 meters high will be excavated. The bottom of the caverns will be 100 meters below ground level. The underground caverns will be filled with hot water. Pressure will be created within the space, allowing the water to reach temperatures of up to 140 degrees without the water boiling or evaporating. Varanto is part of the intelligent and innovative Vantaa district heating system aiming to be carbon-negative by 2030. Read more: HTTP://