New polymer tubes help Finland store 14 GWh of heat a mile underground

A waste-to-energy plant in Salo, Finland, has implemented an innovative underground heat storage system using glass fiber reinforced polymer (GFRP) tubes to capture and store up to 14 gigawatt-hours (GWh) of excess heat a mile (1.2 miles) underground in granite bedrock. Developed through a collaboration between the Lounavoima plant, Exel Composites, and geothermal firm QHeat, this system preserves surplus heat generated from waste incineration during warmer months and releases it in winter to heat approximately 700 detached houses. This approach reduces reliance on fossil fuels, particularly oil burners previously used during Finland’s harsh winters, thereby lowering emissions and improving energy efficiency. The GFRP tubes are specially engineered to withstand the high pressure and temperatures of underground storage while providing enhanced thermal insulation. Lightweight, corrosion-resistant, and designed for easy assembly and sustainable end-of-life reuse, the tubes exemplify advanced engineering solutions to energy storage challenges. The project addresses broader energy issues