Optimisation of a theoretical district heating system with seasonal thermal energy storage

A novel model was used to simulate how an existing district heating (DH) network for Holywell Park, Loughborough University (Loughborough, UK) could be transitioned to low/zero carbon heat. A simulation which includes heat pumps (HPs) and evacuated-tube solar thermal collectors (ETSTCs) to both provide heat for buildings and charge a potential seasonal thermal energy storage (STES) system was performed. Both a) real historic half-hourly CO₂ emissions per kWh of electricity and b) real historic half-hourly heat demands for Holywell Park for the year 2021 were used in the simulations. The model assumes that HPs can only be used to charge STES systems at those times when the CO₂ emissions associated with grid electricity are zero. A parametric analysis was used to investigate the effect of a) the inclusion of STES in the DH system and b) when including the STES 1) the volume of STES system and 2) maximum amount of zero-emissions electricity available to charge STES (E_{CO2 = 0, STES}) on the levelised cost of heat (LCOH) for a 23 year simulation period.