An Approach to Capturing Residual Energy From the Subway System: Methodological Considerations

Urban heating and cooling demands account for a significant portion of global energy consumption. It is crucial to explore new energy resources and innovative solutions to meet environmental targets. Urban infrastructures like data centers, water networks, and tunnels move and collect energy, in some cases residual energy, that is valuable because of its proximity to consumers. The novelty of this work lies in the exploration of utilizing the accumulated residual heat that is not used in subway air to improve the energy efficiency of urban areas. The work focuses on the potential use of this residual heat by the installation of heat pumps in subway platforms or tunnels. By installing a heat pump on subway platforms or tunnels, this residual heat can be efficiently utilized for heating demand or producing domestic hot water. A general methodology for assessing the performance of such air source heat pumps in the subway context is presented. The calculation of the coefficients of performance (COP) and seasonal coefficients of performance (SCOP) calculation is outlined, with a detailed example illustrating the methodology. The paper emphasizes a comparative analysis between the proposed system and a traditional heat pump using ambient air, highlighting the advantages of the proposed approach. Finally, the paper concludes with a brief analysis of the different effects of refrigerants on the system performance for the same boundary conditions. Results are promising, increasing the energy efficiency of big cities and reducing CO2 emissions.