Advancing the decarbonization of thermal energy supply in Southern Europe: the potentialities of High Temperature Aquifer Thermal Energy Storage in Energy Districts

Seasonal thermal energy storage, coupled with district heating networks, offers a promising solution for the decarbonization of thermal energy supply in cities. This study evaluates the energy and environmental benefits of integrating a high-temperature aquifer thermal energy storage system into a district heating network in Tirano, northern Italy. The goal is to assess the feasibility of achieving a carbon-neutral thermal energy supply by incorporating renewable-based technologies and long-term thermal energy storage within a complex energy system. Except for a diesel-fuelled backup boiler, renewable-based systems, including biomass boilers and a cogeneration plant, are used for thermal energy supply. TRNSYS 18 is employed to model all energy conversion systems, with dynamic simulations based on real data for users’ heating loads. The aquifer fluid dynamics model is developed using FeFlow. The results show significant energy and environmental benefits. The proposed system relies almost entirely on renewable energy, with minimal dependence on fossil fuels. Moreover, the layout enables the sharing of excess renewable electricity. Specifically, the electricity generated by the cogeneration plant exceeds the demand of the plant’s auxiliaries, making surplus energy available for other users in the municipality. From an environmental perspective, full carbon neutrality is achieved, assuming that renewable sources are emission-free.