A sand battery is a high temperature thermal energy storage system, developed by the Finnish company Polar Night Energy, that heats sand or a similar solid material with electricity, often surplus wind or solar power, and holds that heat until it is discharged for district heating or industrial use. Polar Night Energy built the world first commercial sand battery in Kankaanpaa, Finland, which drew wide attention after a BBC News report in July 2022, and the company has since built larger versions, including a 100 megawatt hour unit commissioned in 2025 that became the main heat source for the Pornainen district heating network.
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MaturityTRL 3: Experimental Proof of Concept 1 Sources
1. Polar Night Energy: What Is a Sand Battery?
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