Optimisation for interconnected energy hub system with combined ground source heat pump and borehole thermal storage

Ground source heat pumps (GSHP) give zero-carbon emission heating at a residential level. However, as the heat is discharged, the temperature of the ground drops, leading to a poorer efficiency. Borehole inter-seasonal thermal storage coupled with GSHP maintains the efficiency at a high level. To adequately utilize the high performance of combined GSHP and the borehole system to further increase system efficiency and reduce cost, such a combined heating system is incorporated into the interconnected multi-carrier system to support the heat load of a community. The borehole finite element (FE) model and an equivalent borehole transfer function are proposed and respectively applied to the optimisation to analyze the variation of GSHP performance over the entire optimisation time horizon of 24 h. The results validate the borehole transfer function, and the optimisation computation time is reduced by 17 times compared with the optimisation using the FE model.