Due to the increasing share of renewable energies in electricity generation as part of the energy transition, there is also a growing need for energy storage systems that can bridge the time lag between generation and consumption. Carnot batteries (CB), which store electrical energy by converting it into thermal energy, represent one possible form of storage. The central components of a CB are the compression and expansion machines (charging/discharging cycle). Costs can be saved by choosing a machine type that can be operated as both a compression and an expansion machine.