In Finland, the first completely functional sand battery has now been installed. It is a technology that could be used to keep homes warm throughout the winter because it can store sustainably generated heat for extended periods of time. It functions by heating 100 tonnes of sand using electricity produced by solar or wind energy.
Polar Night Energy, a company that calls itself an "innovator of seasonal heat storage," created the battery.
The company claims that this solution enables the up-scaling of solar or wind energy to up to 100% of your heating and electricity demand. The core of our solution is our patented high-temperature, large-scale heat storage.
Explaining the process of this energy storage, the company said that they "convert electricity to heat, and store it for later use. We use sand as the storage medium, which leads to safe operation and a natural balance in the storage cycle. Additionally, sand is a cheap and abundant material that can be heated up to 1000 degrees Celsius and even higher."
"Inside the sand, we build our heat transfer system that enables effective energy transportation to and from the storage." "Proper insulation between the storage and the environment allows for months of storage with minimal heat loss."
According to the company, it has built its first commercial sand-based heat storage facility at Vatajankoski, an energy utility based in western Finland. It will provide heat for Vatajankoski's district heating network in Kankaanpaa, Finland. The storage has 100 kW of heating power and 8 MWh of capacity. Full-scale utilisation of the storage will begin during the year 2022.
The sand at the core is very far from the boundary, so the heat stored in the core does not easily get lost, even if we wait for days or weeks, Polar Night Energy's lead scientist, Ville Kivioja, told Down To Earth.
"If we look at the sand in the steel silo, then some of this sand is quite close to the boundary structure, say, a distance less than 0.5 meters. This portion of the sand will conduct the heat quite effectively to the boundary structure, and thus this heat gets partly lost over time," Kivioja said.
Sand or sand-like materials are used as the store medium in a high-temperature thermal energy storage system known as a "sand battery." Sand acts as a heat reservoir for energy. Its primary function is to serve as a high-power and high-capacity energy storage system for extra wind and solar energy. The energy is converted into heat, which can be utilised to heat buildings and other uses.
