Sand batteries hailed as energy game changer

Batteries made of sand could help provide clean and affordable energy which could store energy for months at a time, according to Finnish developed Polar Night Energy.

The patented high-temperature large-scale heat storage uses sand as its medium to store heat, so that electricity from solar or wind power could be converted to heat the sand when there is excess demand, then it can be used later.

The new technology could be used to heat homes and businesses as well as for electricity grid balancing, it added.

Sand has been chosen as it is abundant, cheap and can be heated up to above 1000° Celsius, as well as providing four times the energy capacity of water.

The first device, where 100 tons of sand is held inside a 4m wide by 7m high steel container, has been installed in the power plant run by Vatajankoski, the company that provides 

“The construction of the storage went well, especially considering that the solution is completely new,” said Polar Night co-founder and chief technology officer Markku Ylönen in a statement.

“We managed to get everything in order despite some challenges and a short delay.”

He said the first installation has shown that the system “has even more potential than we initially calculated”.

As a material, Ylönen said as well as being inexpensive sand is durable 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.

“Heat storages can significantly help to increase intermittent renewables in the electrical grid. At the same time, we can prime the waste heat to usable level to heat a city,” said Ylönen. “This is a logical step towards combustion-free heat production.”

Vatajankoski, which has invested in the first sand battery, 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, Polar Night said 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.

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