Sand battery

Context: Recently a Finland based company came up with sand-based battery to provide clean energy solution for Europe’s energy crisis. It is currently operational at town of Kankaanpaa in Finland.

About Sand Battery:

• It is a type of energy storage device that uses sand or sand-like materials as the storage medium.
• Sand is a very effective medium for storing heat and loses little over time.
• The sand is charged with electricity and then discharged to produce power.
• Its purpose is to work as a high-power and high-capacity reservoir for renewable energy.
• Sand batteries can help to increase the use of renewable energy by allowing excess/surplus energy produced from renewable sources to be stored and used at a later time.

Key Features: The sand battery has three major interconnected components:

• Steel silo: It contains 100 tonnes of sand where the heat is stored.
• Electric air heater: Resistors are used in regular ovens and an air-to-water heat exchanger.
• Heat Exchanger: It has a mechanical pipe and water.
• Sand stores the heat at around 500 Celsius (the same process that makes electric fires work).
• Sand is at the core and very far from the boundary so the heat stored in the core does not easily get lost
  • It can last days or weeks.
• Reservoir is so well-insulated from the outer environment that it can retain temperatures up to 600 degrees Celsius and prevent heat losses over time.
• It can store up to 8 megawatt-hours of energy as heat.

Working conditions:

• It receives electricity from grid through cheaper renewable sources like solar and wind.
• Electricity is converted to heat and transferred to sand.
• Air is blown via a fan through the curricular pipe system inside the silo.
• It will enter the electric air heater, where it becomes hot with the help of a resistor located inside.
• Hot air will be circulated by air-to-water heat exchanger through metal structure (pipes).
• There’s no direct contact between air and water.
• Hot water is discharged into district heating system.
• It circulates in close loop from the heat exchanger to the customer and back.
• Energy is stored as heat which is used to heat homes or to provide hot stream and high temperature process heat to industries that are often fossil-fuel dependent.

Source:  DownToEarth