Sand heat storage with circulating sand reduces energy costs and CO₂ emissions

Finnish start-up The Storage has installed a heat storage system based on circulating sand in a pilot project, which stores electricity produced by renewable energies in the form of heat and can release it again when needed. According to the company, the system is expected to save up to 70 percent of the conventionally incurred electricity costs in industrial use and reduce CO₂ emissions by up to 90 percent.

The energy demand for industrial heat production worldwide accounts for about one-fifth of the total energy consumption. A large part, about 80 percent, is still generated by fossil fuels such as oil and gas. The heat storage battery from The Storage, on the other hand, uses electricity from renewable energies to convert it into heat with a heater, store it in a sand heat storage system, and release the heat again when needed – also in times when renewable energies, such as wind turbines, can produce little or no electricity due to low wind.

The Storage's technology is called “Sand in Motion.” The concept for the technology originated in 2023. Development and implementation of the sand heat storage system then took place in 2024 and 2025. In January 2026, a system was commissioned together with a brewery on an industrial scale to test the function and effectiveness of the Sand-in-Motion concept. The heat from the heat storage system is used by the brewery to generate fossil-free steam for the brewing processes.

Circulating Sand for Higher Energy Efficiency

The principle of The Storage's sand heat storage system uses two silos filled with sand. One contains cool sand, and the other stores already heated sand. The cool sand is transported to a heater, which heats it to up to 800 °C with electricity from renewable energies and stores it stationary in the hot silo. The hot sand can be retrieved from there as needed and then flows through a heat exchanger, which generates hot steam. Due to the circulation of the sand, the heat transfer efficiency is up to ten times higher than in conventional static systems, The Storage explains.

Depending on the industrial application, the heat can be released in the form of steam or also via thermal oil. In its current form, the system can retrieve the energy stored in the hot sand as needed. Cost savings of up to 70 percent and a reduction in CO₂ emissions of up to 90 percent are possible compared to conventional production plants.

The heat sand battery can be scaled according to industrial requirements, allowing storage capacities between 20 MWh and 500 MWh. The charging power is between one and 20 MW.

The company Polar Night Energy operates the world's largest sand heat storage system in Pornainen, Finland. It can store energy of up to 100 MWh and supplies households with district heating. This plant has been in operation since mid-2025 and is expected to reduce CO₂ emissions by about 70 percent. The company is already working on the implementation of a larger sand heat storage system that can store up to 250 MWh of energy.

(olb)