Finland invented the world's first sand battery

Finland has built the world’s first sand battery, which can store heat from a variety of energy sources for months.

The battery is a massive steel silo 7 m tall and 4 m wide with 100 tonnes of sand that will be placed in the Finnish town of Kankaanpaa in June 2022.
It is linked to the town’s centralized heating system, which maintains buildings and public water systems warm.

The storage system has three main components:

The electrical air heater heats the air to 600°C for filling the sand silo.
The hot air is then circulated within the silo via a heat exchange pipe and blowers, raising the temperature of the sand at the silo’s center to 600°C.
The blowers are used to pump air into the conduit inside the sand silo when the storage reaches the discharging stage.
When the air hits 200°C, it is transferred to an air-to-water heat exchanger and used to boil water.
It is then routed to the heating system.

The storage system needs constant power to charge the battery, monitor the temperature while in standby, and operate the blowers when the battery is used.
The installed battery can hold 8 megawatt-hours (MWh) of energy and emit heat at 0.1 MW, enough to heat and supply hot water to approximately 100 homes and a public swimming pool.

Because of its benefits, the Finnish researchers replaced water in the battery system with sand.
Sand can withstand temperatures of up to 600 degrees Celsius (°C), whereas water begins to simmer at 100°C.
It also has a low heat conductivity, which helps to minimize energy loss.

According to the International Energy Agency, heat accounts for half of global energy consumption, followed by transportation (30%) and power (20%). (IEA).
Currently, dirty fossil fuels provide 80 percent of the world’s electricity.

Source: https://www.indiatimes.com/explainers/news/finland-develops-worlds-first-fully-working-sand-battery-574542.html