Sensible heat storage
Storing heat by warming a material: water, molten salt, sand, rock, bricks or underground stores.
Storage · Thermal · No. 83
- Storage
- Duration: Hours to seasons
A Finnish town heats its homes from a 100 MWh pile of hot soapstone, letting it stop burning oil entirely.
Chart: Illustration: Sensible heat storage
Where it comes from
Chart: Map of where it comes from
Electricity heats a cheap material such as water, sand, rock or brick; Antora has demonstrated stores above 1,800 C.
Three things to know
- Water stores about 70 kWh per tonne over a 60 C swing (calculated), using a material costing about USD 0.005 per kg.
- Heat in, heat out is very efficient, but turning stored rock heat back into electricity manages only about 25% today.
- At least six European countries had over 500 hours of negative power prices in 2025, free fuel for heat stores.
The journey
- 1 Cheap powerCharged in the cheapest or negative-price hours
- 2 HeatersResistive elements warm the material
- 3 StoreWater, sand, rock, brick or molten salt
- 4 InsulationKeeps heat for hours to seasons
- 5 Heat outHot water, steam or industrial process heat