Finland has installed the world’s first sand battery that can store heat from renewable energy sources for months.
Key points
- Heat alone accounts for half of the world’s energy use, followed by transport (30 per cent) and electricity (20 per cent).
- Currently, 80 per cent of the world’s energy comes from dirty fossil fuels.
- The battery, 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 connected to the town’s centralised heating network that keeps buildings and public water systems warm.
- 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.
- The storage system has three main components: the sand silo, an electrical air heater and an air-to-water heat exchanger.
- 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.
- The storage system requires electricity at all times. It is needed 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 in Kankaanpää — for 80 hours on a full charge.
