In a few years, the world's largest sand battery will be built in the energy storage facility of Pornainen, located in southern Finland. This innovative battery will be able to store 100 MWh of thermal energy derived from solar and wind sources. The energy stored will be used to eliminate heating oil from the district heating network, which will help to reduce greenhouse gas emissions by almost 70%.

In May of 2022, Polar Night Energy, the manufacturer of the new 1 MW sand battery, connected a smaller version of the battery to a power plant in the Finnish city of Kankaanpää. The project was launched in response to Russia cutting off gas supplies as a retaliation for Finland joining NATO. This sand battery is a revolutionary way of harnessing renewable energy.

In 2018, Euronews Green interviewed two Finnish entrepreneurs, Tommi Eronen and Markku Ylönen, who devised an innovative technology to tackle the energy storage problem in the northern regions. The duo explored various ideas and stumbled upon sand as an inexpensive and efficient way to store the electricity generated by renewable sources such as wind and solar power. They found that sand grains are surprisingly capable of storing energy.

Finding a way to store excess renewable energy is crucial for unlocking its full potential. Lithium batteries, while effective for certain applications, have limited capacity and pose environmental concerns.

Sand has the ability to store heat at temperatures up to 500 degrees Celsius for several days to months. This makes it a valuable source of cheap and clean energy during the winter months. The sand battery is used to emit hot air when required, which is then used to heat water in the district heating network. In Tampere, Finland, homes, offices, and even a local swimming pool utilise this technology.

Representatives from Polar Night Energy have described their prototype as a fairly simple design. The tower is filled with low-quality sand and is charged with heat from excess solar and wind energy. This process is achieved through resistive heating, which generates heat from the friction created when an electric current flows through any non-superconductive material. The hot air is then evenly distributed throughout the tank.

"There’s really nothing fancy there," Markku says of the storage. "The complex part happens on the computer; we need to know how the energy, or heat, moves inside the storage, so that we know all the time how much is available and at what rate we can discharge and charge."

After refining its charging algorithms, Polar Night Energy is ready to scale up its storage technology at the new Pornainen tank. The sand battery will be about ten times larger than the one still operating at the Vatajankoski power plant in Kankaanpää.

As Euronews reported, the Mayor of Pornainen Antti Kuusela says the municipality "welcomes all innovative development projects that reduce emissions in district heating operations and contribute to network expansion." The sand battery is expected to reduce emissions by 160 tonnes of carbon dioxide per year. In addition to making the city less dependent on oil, wood burning is expected to fall by 60%.

The 13-meter-high and 15-meter-wide sand battery will be constructed and tested over 13 months. It should be ready to provide heat to the residents of Pornainen well before winter 2025.

Source: euronews.com