Sand Battery: Revolutionizing Renewable Energy Storage

In a groundbreaking development, Finland has introduced the world’s first sand battery. This is capable of storing heat generated from renewable energy sources for extended periods. This technology has the potential to tackle the persistent issue of maintaining a stable energy supply from intermittent renewable sources.

The achievement’s importance is having roots in the fact that heat accounts for almost half of the world’s total energy consumption.
Heat is followed by transportation, which makes up 30 percent of global energy consumption, and electricity, which accounts for 20 percent of the total.
These figures are according to data from the International Energy Agency (IEA).

Presently, 80 percent of the world’s energy is derived from fossil fuels, contributing to environmental degradation.

The Sand Battery: A Simple yet Effective Solution

The sand battery, housed within a massive steel silo, 7 m tall and 4 m wide with 100 tonnes of sand, was installed in Finland’s Kankaanpää town in June 2022. It is seamlessly integrated with the town’s centralized heating network, which serves as the primary source of warmth for residential and public water systems.

Finland’s widespread use of centralized heating networks, often powered by renewable sources, makes it an ideal location for this revolutionary sand battery. These networks are essential in combating the country’s cold climate.

What sets the sand battery apart is its utilization of sand instead of water for energy storage. Sand can withstand temperatures of up to 600 degrees Celsius, significantly higher than water’s boiling point at 100 degrees Celsius. Moreover, sand exhibits lower heat conductivity, leading to reduced energy loss. This promising technology is developed by Polar Night Energy, a Finnish company.

How the Sand Battery Works

The sand battery consists of three key components: the sand silo, an electrical air heater, and an air-to-water heat exchanger.

Charging Phase:

In the charging phase, the electrical air heater heats the air to 600°C. The electrical air heater circulates the hot air within the silo through a heat-exchange pipe and blowers, raising the core sand temperature to 600°C.

Discharging Stage:

During the discharging stage, the pipe inside the sand silo receives a pump of air. The air, when it reaches 200°C, undergoes transfer to the air-to-water heat exchanger. In the air-to-water heat exchanger, it boils water. Subsequently, the heating network receives the heated water.

It’s important to note that the storage system requires a continuous supply of electricity. This power is essential for charging the battery, monitoring temperature during standby periods, and operating the blowers during the battery’s use.

The current installed sand battery can store 8 megawatt-hours (MWh) of energy and release heat at a rate of 0.1 MW. This capacity is adequate to provide heating and hot water for approximately 100 homes and a public swimming pool in Kankaanpää for 80 hours on a full charge. Some companies are in the process of developing a 200 MWh battery capable of discharging heat at 2 MW, catering to the heating needs of 100 Kankaanpää houses over 100 hours.

While the technology holds great promise, it is currently insufficient to meet the heating demands of an entire season. However, some scientist are still, remains optimistic about scaling up the technology. Thus emphasizing that reliance on a single storage system for an entire town is not practical.

Global Potential of Sand Batteries

Polar Night Energy envisions vast applications for the sand battery, even in countries lacking district heating networks. In countries like India, this technology presents significant opportunities for process heating in industries or heating municipal building complexes. It can be adapted for industries requiring more than 10,000 MWh of heating annually.

Conclusion

Pioneering sand battery offers an ingenious solution to the challenge of storing heat from renewable sources. This technology brings us one step closer to ensuring round-the-year availability of clean energy and reducing reliance on fossil fuels. In the ongoing field of renewable energy storage, the sand battery promises to be a game-changer in the transition to sustainable energy sources as innovation continues.