The objective of The Paris Agreement requires a strict average temperature increase in the global level to be 1.5C. Therefore, there is also a surge of demand in renewable energy because of the climate change and expensive yet limited fossil fuel.

However, renewable energy sources such as wind energy and solar energy generally rely on the weather and have uncertainties. They cannot generate electricity based on various demand. Therefore, while increasing investment in them, we also need to do well in energy storage.

From traditional lithium-based "super-large" batteries, to flow batteries, silicon phase change batteries, molten salt batteries, iron-air batteries, gravity batteries, carbon dioxide expansion batteries, and the most recent sand battery in Finland, countries have tried various methods to store energy more efficiently.

Finland: Enables "sand battery" heating system

Finnish startup Polar Night Energy in Vatajankoski power plant have built the world's first [sand battery" which is powered by solar and wind energy - a commercial sand-based high temperature heat storage system.

Sand is durable, less expensive, and very efficient for storing heat with little heat loss over time. In the [sand battery", a steel container with a 4 meters` width and a 7 meters` height has an automatic heat storage system and contains about 100 tons of sand.

But how does a "sand battery" work? Whenever there is excess energy from sun and wind, the sand battery would use this energy to heat the sand to a temperature of 500 Degrees Celsius. Then it creates hot air, which circulates through the sand through a heat exchanger.

The developers say their device allows the sand to store a lot of heat at temperatures between 500 and 600 degrees Celsius for months. The heat storage system can release up to 100 kilowatts of heat and electricity, with an energy storage capacity of 8 megawatts. In the future, the battery will provide energy during Finland's long winters, keeping homes, offices, factories and even the local swimming pool warm.

From Science and Technology Daily / http://www.stdaily.com/

Reference BBC News / https://www.bbc.com/news/science-environment-61996520