Written by: Pamela Jacome
Sand Battery for Loviisan Lämpö at Pornainen, Finland
Polar Night Energy has been recognized as one of the most promising climate and tech startups globally by the German Energy Agency (dena). Selected for the Start-up Energy Transition SET100 List 2026, this Finnish energy technology company was chosen from over 470 applications across 79 countries. This recognition was awarded for their innovative contribution to energy storage solutions, which are necessary for managing the intermittency problem of renewables and accelerating the energy transition. Their approach consists of a Sand Battery technology, which stores energy from renewable sources as high-temperature heat on sand and industrial by-products.
Currently, this Sand Battery technology has been implemented in the municipalities of Kankaanpää and Pornainen to support district heating networks, providing a storage capacity of 8 MWh and 100 MWh respectively. Previously powered by a woodchip-burning plant, the Pornainen district heating network has reduced its carbon emissions by around 70% following this change. Furthermore, at this location, the material being used to store thermal energy consists of crushed soapstone, which is a by-product coming from the company Tulikivi’s fireplace manufacturing. By utilizing by-products, this innovation does not contribute to a global shortage of river sand, which is expensive and already in high demand in the construction sector. Ultimately, this sand battery technology also contributes to a more circular economy by turning fireplace manufacturing waste into a value-added product.
This relatively new technology has already begun demonstrating great potential for decarbonising industrial heat emissions, and has more inspiring projects in the making. Tommi Eronen, the CEO of Polar Night Energy, has stated how he is “excited for the future” and wants to “have a positive impact on the world.” For 2027, the company plans to inaugurate the world’s largest sand-based thermal energy storage system at Vääksy, Finland, which will have a capacity of 250 MWh. Implementing the sand battery will reduce reliance on natural gas and woodchip, which is expected to cut fossil-based emissions in the Vääksy district heating network by 60% annually. Polar Night Energy’s revolutionary sand battery technology serves as a clear example of how science and innovation are continuously advancing through mission-driven people and offer a promising path for the energy transition.
Sources:
https://finland.fi/business-innovation/finnish-company-creates-an-innovative-sand-battery
https://polarnightenergy.com/news/polar-night-energy-selected-for-the-set100-list-2026
https://polarnightenergy.com/news/worlds-largest-sand-battery-inaugurated/
https://polarnightenergy.com/reference/decarbonizing-heating/