Steel production is a highly energy- and emission-intensive process. Compared to the production via the integrated route, the melting of recycled steel scrap and directly reduced iron in an electric arc furnace operated on green power constitutes a way to reduce energy consumption and CO2-emissions. However, there is still potential to reduce energy consumption and CO2-emissions in electric arc furnace steel production by introducing new sub-processes, optimal operational design, and integration of renewable energy sources. For complex industrial processes, this potential can only be determined using models of the entire system. The batch operation, changing process parameters, and strongly fluctuating energy consumption require a holistic, temporally, and technologically resolved model. Within the scope of this paper, we describe an energy system model of an electric arc furnace steel mill. It allows assessing the optimal implementation of novel technologies and system integration of renewable energy sources using a reduced set of input parameters. The modular design facilitates the extension of the model, and the option of specifying several input parameters enables the model to be adopted for other electric steel mills.