The first Commercial Sand-based Thermal Energy Storage in the World

Polar Night Energy’s first commercial sand-based high-temperature heat storage is now in operation at the Vatajankoski power plant area. The heat storage, which has a hundred tons of sand inside, is producing low emission district heating to the city of Kankaanpää in Western Finland. BBC made a story about Polar Night Energy’s heat storage solution.

Polar Night Energy and Vatajankoski, an energy utility based in Western Finland, have together constructed sand-based thermal energy storage. It is the world’s first commercial solution to store electricity in the sand as heat to be used in a district heating network.

The storage, with Polar Night Energy’s patented heat storage system inside, is placed on Vatajankoski’s power plant area, and it provides heat for Vatajankoski’s district heating network in Kankaanpää.

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

– We have already learned that our system has even more potential than we initially calculated. It’s been a positive surprise.

The actual heat storage is about 4 meters wide and 7 meters high steel container that has an automated heat storage system and a hundred tons of sand inside. As a material, and is durable and inexpensive and can store a lot of heat in a small volume at a temperature of about 500–600 degrees Celsius.

The heat storage has 100 kW of heating power and 8 MWh of energy capacity.

– This innovation is a part of the smart and green energy transition. Heat storage can significantly help to increase intermittent renewables in the electrical grid. At the same time, we can prime the waste heat to a usable level to heat a city. This is a logical step towards combustion-free heat production, says Ylönen.

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 75–100 degrees before it is fed into the district heating network.

Vatajankoski provides district heating and cooling services as well as electricity distribution services to its clients in the Kankaanpää region in Western Finland and aims to produce its energy as sustainably as possible. / www.vatajankoski.fi

Polar Night Energy designs and builds high temperature & low emission heat storages. / www.polarnightenergy.fi