The current energy system is facing major challenges due to the energy transition that is being sought at national and European level. Based on the expansion of renewable energy sources and their volatile nature, an increasing demand for ancillary services caused by bidirectional load flows between the transmission and distribution network can be expected. However, electromobility serves as an important pillar in realizing the transformation of the energy system. In the present work, within the scope of the "FlyGrid" project, the provision of ancillary services using electric vehicles based on the "Vehicle-to-Grid" concept is examined. In addition, the use of flywheel energy storage systems (FESS) as decentralized energy storage is analyzed. For this purpose, the demand for ancillary services in terms of redispatch measures, secondary and tertiary control reserve in the year of 2019 is determined and a forecast for the year 2030 is compiled. Furthermore, a model is created for simulating the behavior of electric vehicles in different use cases and FESS. In this model various charging and discharging capacities as well as electromobility penetrations are analyzed. The potential of electric vehicles, alone and in combination with FESS, is calculated based on current and future demand figures. In a further step, the impacts of the determined potential on a rural medium-voltage network, operated by Energienetze Steiermark GmbH, are investigated based on long-term load flow simulations (NEPLAN). This study demonstrates that electric vehicles are perfectly suitable for the provision of ancillary services. In particular, the use cases "work" and "charging at home" can provide a substantial contribution to covering the need for ancillary services assuming a sufficient penetration of electromobility. The contribution of FESS, on the other hand, is rather small, since within the scope of the study they are not designed to provide ancillary services, but rather to cover peak loads at short notice, which are caused by high-power charging. Long-term load flow simulations illustrate that low charging and discharging power are unproblematic for the existing electrical network. In contrast, thermal overloads and inadmissible node voltages result from using increasing power. Consequently, the future provision of ancillary services by electric vehicles requires low charging and discharging power, in order to prevent potential grid expansion measures.