Electrical Storage Design in Multi-Energy Systems: Impact of Component Model Choice

The transition towards coupled energy sectors within multi-energy systems (MES) requires explicit modelling of more components and thus requires careful decisions on the level of modelling details. The focus commonly lies on one energy sector, with strong simplifications for the remaining coupled energy sectors. However, the impact of model choice on the MES planning solution is largely unexplored. This work therefore sets out to investigate the impact of component model choice in an MES with electricity and heat for sizing a community battery energy storage system (BESS). Our analysis examines the impact of the choice of model of the power grid, the heating network, the heat pump, and the thermal building. Our results show a 49% increase in BESS size when using the convex second-order cone formulation compared to the exact nonlinear AC OPF equations for the power grid. The linear formulation results in 58% oversizing and suboptimal placement of the BESS. Furthermore, explicitly modelling the heating network does not significantly impact the design results but increases the computational efforts. Different heat pump models show minimum impact on the BESS design and location, thus our findings suggest that linear models for the heat pump are suitable. However, omitting thermal demand and storage capabilities overestimates the BESS size by 42%. This further emphasizes the necessity of explicitly modelling the coupled heating sector and its thermal inertia for realistic electrical storage designs.