Finland has inaugurated an industrial-scale sand battery this week in the southern town of Pornainen, where it'll take over heating duties from an old woodchip power plant for the municipality. It's set to reduce carbon emissions from the local heating network by as much as 70%, and is the largest…
More likely construction cost. Deep excavations are expensive, it’s much cheaper to just install a concrete pad and land things on top of it.
Construction costs are a one-time expense, though.
Is it cheaper to maintain over the course of the unit’s lifespan above or below ground?