Interesting. Does anyone know what source of electricity is going to be used for this ? Probably solar but it might be also useful with coal plants or wind farms that produce even when there is not enough demand. How are they moving the heat ?

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crishoj 11 hours ago | parent | next [-]

It's a heat battery for district heating. Could be other sources than electricity, e.g. municipal garbage incineration plant.

	▲	Maxion 3 hours ago \| parent [-]
		No, these generally use excess power during the night and windy days to store heat. There's not that much CHP production that there'd be excess, plus they can adjust those plants well enough that there's no unnecessary burning going on.

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Hamuko 27 minutes ago | parent | prev | next [-]

Most likely not solar since there’s almost no solar during the winter months. Sun comes up at 0900 and goes down at 1500 in the south. In the north it’s worse.

What might be plentiful is wind, especially during the nights.

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whizzter 11 hours ago | parent | prev | next [-]

See my other comment about Nordic power balancing.

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perihelions 10 hours ago | parent | prev [-]

Natural gas and wood chips,

> "The installation will supply heat to the Vääksy district heating network and is expected to lower fossil-based emissions by approximately 60% annually, primarily through an estimated 80% reduction in natural gas consumption and reduced reliance on wood chips."

https://www.pv-magazine.com/2025/11/25/finlands-polar-night-...

	▲	jonners00 10 hours ago \| parent [-]
		Those are the energy sources they're replacing with this tech - according to <https://reneweconomy.com.au/new-worlds-largest-sand-battery-...> it's surplus energy from renewables that will 'charge' the battery (so likely wind, hydro and solar that is produced but surplus to the grid's requirements)