What is the Sand Battery System?
- The battery is a massive steel silo, 7 m tall and 4 m wide with 100 tonnes of sand, and was installed in Finland’s Kankaanpaa town in June 2022.
- It is connected to the town’s centralised heating network that keeps buildings and public water systems warm.
- The storage system has three main components:
- Sand silo,
- Electrical air heater, and
- Air-to-water heat exchanger
Working principle
- For charging the sand silo, air is heated to 600°C in the electrical air heater.
- The hot air is then circulated inside the silo using a heat-exchange pipe and blowers to raise the temperature of the sand at the silo’s core to 600°C.
- When the storage enters the discharging stage, the blowers are used to pump air into the pipe inside the sand silo.
- Once the air reaches 200°C, it is transferred to the air-to-water heat exchanger, where it is used to boil water.
- It is then sent to the heating network.
Electricity Requirements and Capacity of the Battery
- The storage system requires electricity at all times to charge the battery, monitor the temperature during standby, and run the blowers when the battery is used.
- The installed battery can store 8 megawatt-hours (MWh) of energy and release heat at 0.1 MW, which is enough to provide heating and hot water for about 100 homes and a public swimming pool.
Advantages of Sand as a Heat Storage Material
- The Finnish researchers replaced water with sand in the battery system because of its advantages.
- Sand can be heated up to 600 degrees Celsius (°C), whereas water starts to boil at 100°C.
- It also has low heat conductivity, which reduces energy loss.
Importance of Heat Energy
- Heat accounts for half of the world’s energy use, followed by transport (30 per cent) and electricity (20 per cent), as per the International Energy Agency (IEA).
- Currently, 80 per cent of the world’s energy comes from dirty fossil fuels.