Worlds first sand battery can store green energy for months

Polar Night Energy in Finland has completed the installation of a battery system that uses around 100 tonnes of sand as its main component, storing green energy in the form of heat for months at the Vatajankoski power plant, which operates the district heating system. Sand is a highly efficient heat storage medium with little loss over time.

Climate change and rising fossil fuel prices are prompting many organizations and companies to invest in renewable energy production.

Solar panels and wind turbines are being invested in by many organizations and companies to produce renewable energy. However, the challenge is how to maintain electricity when the sun is not shining and the wind is not blowing?

Additionally, adding more renewable energy to the grid needs to be accompanied by grid balancing solutions, as too little or too much electricity can have negative consequences.

A large-scale battery system capable of storing and balancing energy demand is needed to overcome this problem. However, most batteries today are made of lithium, which is very expensive for its large size and is also not very efficient.

Sand batteries, whose key component is about 100 tons of sand piled inside a silo (tall, round tower), can store green energy for months.

How the sand battery works: Sand is heated to 500 degrees Celsius by using cheap surplus electricity to heat a resistor. This process, using a heat exchanger, creates hot air that circulates through the sand. According to Polar Night Energy, their device can keep sand at 500 degrees Celsius for several months.

When needed, the batteries release hot gas to warm water for district heating systems. The water is then pumped to homes, offices, and even swimming pools, helping to alleviate concerns about heat during Finland’s long, cold winters.

One of the big challenges right now for Polar Night Energy is scaling up the sand battery technology to really make a difference and getting it used by developers to generate electricity as well as heat?

Experts have found that using sand simply to return stored electricity to the grid is not very efficient. However, most of the heat used for food, beverage, textile and pharmaceutical production today comes from burning fossil fuels, so storing green energy as heat for long periods of time has huge benefits for industry.