Shallow geothermal energy application with GSHPs at city scale: study on the City of Westminster

Geothermal energy is an efficient low carbon solution for the heating and cooling of buildings. For many megacities such as London and Beijing, the amount of energy that can be stored in the urban local subsurface is greater than their annual heating and cooling demands. The ground source heat pump (GSHP) system - a shallow geothermal technology that provides heating and cooling for buildings by continuously replenishing the energy in the subsurface - has been used increasingly in recent years, but its application has been generally limited to single buildings. In this study, a geographic information system-based simulation model was developed to estimate how many GSHPs could be installed at the city scale without losing control of the ground thermal capacity and to evaluate the degree to which such a system could contribute to the energy demands of buildings in a city. The model was built by embedding a Python-based GSHP design code into ArcGIS software and was trialled on the City of Westminster, a borough in London, UK, as a case study under the two scenarios of boreholes placed under buildings and boreholes around buildings. Under both scenarios, the model produced borehole allocation maps and ratio of capacity to demand maps. The results show that a large proportion of buildings could support their own heating demands through GSHPs and, through a well-organised district heating system, GSHPs may be used efficiently to satisfy heating demands throughout an urban area.