Estimation of the technical geothermal potential through energy piles at a small regional scale: A campus case study

Energy piles are a new form of building energy-saving structures developed from traditional ground source heat pump technology, with great potential in urban spatial development. Utilizing large-scale energy piles to extract shallow geothermal energy can contribute significantly to reducing the carbon emissions of building clusters. A method to estimate the technical geothermal potential through energy piles was proposed at a small regional scale, integrating the attributes of buildings in the region, the thermophysical properties of the ground, and the design parameters of energy piles. Based on the finite-length cylindrical heat source model, it considered the fluid threshold temperature and thermal interference between piles. The method was applied to a campus in Nanjing, China, as a case study and the factors affecting the heat exchange performance of energy piles were analyzed. The results showed that the virtual installation of 14,799 energy piles beneath 141 buildings in the campus could inject approximately 9961 MWh of heat into the ground annually in summer and extract about 15,542 MWh of heat from the ground annually in winter. The estimated technical geothermal potential can provide strategic support for urban planners and policymakers.