Finland has recently activated the world's largest sand-based battery, marking a significant advancement in thermal energy storage technology. 2 GWh currently in operation and a further 0. A similar growth in thermal energy storage sys ems. In 2024, 95% of Finland's electricity production was covered by fossil-free electricity – ie, nuclear, wind, hydro and solar power – with renewable energy sources accounting for 56% of electricity production. For district heating, 73% was produced by biofuels as well as waste heat and electric. ing new industries, such as data centres and hydrogen production facilities. Simultaneously, firm capacity wil gradually reduce in the Finnish power system as older thermal units retire.