Sand-based system for seasonal storage comes online in Finland


Finnish utility Vatajankoski and Finland-based startup Polar Night Energy have switched on a sand-based high-temperature heat storage system that will provide district heating to the western Finnish city of Kankaanpää.

The storage facility is located in the area of an unspecified power plant operated by Vatajankoski and has 100 kW of heating power and 8 MWh of energy capacity. It is embedded in a 4 m x 7 m high steel container and is able to store electricity in the form of heat for several months at temperatures ranging between 500 and 600 C.

“The construction of the storage went well, especially considering that the solution is completely new,” said Polar Night Energy CTO Markku Ylönen. “We managed to get everything in order despite some challenges and a short delay. Now the sand is already hot.”

Vatajankoski uses the heat provided by the storage to prime the waste heat recovered from their data servers which are intended for high-performance computing. “Depending on the season, the temperature of the 60-degree waste heat from the servers must be raised to 75 to 100 degrees before it is fed into the district heating network,” Polar Night Energy said in a statement.

Popular content

A small pile of sand at the storage site.

Image: Polar Night Energy

The company said the size of the system may vary from tens to thousands of cubic meters and be located either in a cylinder, as for the project in Kankaanpää, or underground, reserving minimal space from the often highly valued square meters on construction sites.

The system uses common dry sand without any special treatment as the storage medium and works with pipes containing air. When this air is heated up, it is pumped through the pipes and reaches the sand, which is in turn heated up to up to 600 C.

Similar systems were recently developed by the US Department of Energy's National Renewable Energy Laboratory (NREL) and Magaldi Green Energy, a unit of Italy-based dry bottom ash handling system provider Magaldi Power Spa.

This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: