Seasonal thermal energy storage (STES), also known as inter-seasonal thermal energy storage, is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever needed, such as in the opposing season. Phase Change Materials, integrated into building materials, absorb and release heat to regulate temperature passively. Solar-Powered Seasonal Heat Banks capture summer sun to warm your. The key drivers for the need for seasonal energy storage are highlighted, primarily the increasing deployment of VRE and the seasonal nature of renewable energy sources. USES4HEAT demonstrates, at TRL8 and for a one year test campaign, two innovative, cost-effective, large scale, seasonal underground TES. Abstract: Seasonal storage of solar thermal energy or of waste heat from heat and power cogeneration plants will significantly contribute to substitute fossil fuels in future energy systems.