Finnish startup Polar Night Energy and local Finnish utility Vatajankoski have together built the world’s first commercial sand-based, high-temperature heat storage system that can be powered by solar and wind.
Sand-filled energy storage in Finland
Polar Night Energy’s heat storage system is a 23-foot-tall steel container filled with 100 tons of sand. (Polar Night Energy uses the lowest grade of sand that isn’t used in construction.) Hot air blown through pipes heats the sand in the steel container by resistive heating.
The sand is able to store heat at around 500–600C (932–1,112F) for months, so power generated in the summer can be used to heat homes in the winter. Polar Night Energy says it has 100 kW of heating power and 8 MWh of energy capacity. Here’s how it’s meant to work with renewables:
Image: Polar Night Energy
This first sand battery, which is in…